Delayed sleep phase syndrome
Encyclopedia
Delayed sleep-phase syndrome (DSPS), also known as delayed sleep-phase disorder (DSPD) or delayed sleep-phase type (DSPT), is a circadian rhythm sleep disorder
, a chronic disorder of the timing of sleep, peak period of alertness, the core body temperature rhythm, hormonal and other daily rhythms, compared to the general population and relative to societal requirements. People with DSPS generally fall asleep some hours after midnight and have difficulty waking up in the morning.
Often, people with the disorder report that they cannot sleep until early morning, but fall asleep at about the same time every "night". Unless they have another sleep disorder
such as sleep apnea
in addition to DSPS, patients can sleep well and have a normal need for sleep. Therefore, they find it very difficult to wake up in time for a typical school or work day. If, however, they are allowed to follow their own schedules, e.g. sleeping from 4 a.m. to noon, they sleep soundly, awaken spontaneously, and do not experience excessive daytime sleepiness
.
The syndrome usually develops in early childhood or adolescence. An adolescent version disappears in adolescence or early adulthood; otherwise DSPS is a lifelong condition. Depending on the severity, it can be to a greater or lesser degree treatable. Prevalence among adults, equally distributed among women and men, is approximately 0.15%, or 3 in 2,000.
DSPS was first formally described in 1981 by Dr. Elliot D. Weitzman and others at Montefiore Medical Center
. It is responsible for 7–10% of patient complaints of chronic insomnia
. However, as few doctors are aware of it, it often goes untreated or is treated inappropriately; DSPS is often misdiagnosed as primary insomnia
or as a psychiatric condition. At its most severe and inflexible, it is an invisible disability
.
(ICSD), the circadian rhythm sleep disorders share a common underlying chronophysiologic basis:
The ICSD (page 128-133) diagnostic criteria for delayed sleep-phase syndrome are:
Some people with the abnormality adapt their lives to the delayed sleep phase, avoiding common business hours (e.g., 9 a.m. to 5 p.m.) as much as possible. They have the disorder, but for them it is not a disability. The ICSD's severity criteria, all of them "over at least a one-month period", are:
Some features of DSPS which distinguish it from other sleep disorders are:
Attempting to force oneself onto daytime society's schedule with DSPS has been compared to constantly living with 6 hours of jet lag
; the disorder has, in fact, been referred to as "social jet lag". Often, sufferers manage only a few hours sleep a night during the working week, then compensate by sleeping until the afternoon on weekends. Sleeping in on weekends, and/or taking long naps during the day, may give people with the disorder relief from daytime sleepiness but may also perpetuate the late sleep phase.
People with DSPS can be called extreme night owls
. They feel most alert and say they function best and are most creative in the evening and at night. DSPS patients cannot simply force themselves to sleep early. They may toss and turn for hours in bed, and sometimes not sleep at all, before reporting to work or school. Less extreme and more flexible night owls, and indeed morning larks, are within the normal chronotype
spectrum.
By the time DSPS patients seek medical help, they usually have tried many times to change their sleeping schedule. Failed tactics to sleep at earlier times may include maintaining proper sleep hygiene
, relaxation technique
s, early bedtimes, hypnosis
, alcohol
, sleeping pills, dull reading, and home remedies
. DSPS patients who have tried using sedatives at night often report that the medication makes them feel tired or relaxed, but that it fails to induce sleep. They often have asked family members to help wake them in the morning, or they have used several alarm clock
s. As the syndrome occurs in childhood and is most common in adolescence, it is often the patient's parents who initiate seeking help, after great difficulty waking their child in time for school.
The current formal name established in the second edition of the International Classification of Sleep Disorders is circadian rhythm sleep disorder, delayed sleep phase type; the preferred common name is delayed sleep-phase disorder.
DSPS is not uncommon among teenagers; at least one study has indicated that the prevalence of DSPS among adolescents is as high as 7%. Among adolescents, boys predominate, while the gender distribution shows equal numbers of women and men in adults.
A marked delay of sleep patterns is a normal feature of the development of adolescent humans. According to Mary Carskadon
, both circadian phase and homeostasis
(the accumulation of sleep pressure during the wake period) contribute to a DSPS-like condition in post-pubertal as compared to pre-pubertal adolescents.
cycle, might have a reduced response to the re-setting effect of daylight on the body clock and/or may respond overly to the delaying effects of evening light and too little to the advancing effect of light earlier in the day. In support of the increased sensitivity to evening light hypothesis, "the percentage of melatonin suppression by a bright light stimulus of 1,000 lux administered 2 hours prior to the melatonin peak has been reported to be greater in 15 DSPS patients than in 15 controls."
People with normal circadian systems can generally fall asleep quickly at night if they slept too little the night before. Falling asleep earlier will in turn automatically help to advance their circadian clocks due to decreased light exposure in the evening. In contrast, people with DSPS are unable to fall asleep before their usual sleep time, even if they are sleep-deprived. Sleep deprivation does not reset the circadian clock of DSPS patients, as it does with normal people.
People with the disorder who try to live on a normal schedule cannot fall asleep at a "reasonable" hour and have extreme difficulty waking because their biological clocks are not in phase with that schedule. Normal people who do not adjust well to working a night shift have similar symptoms (diagnosed as shift-work sleep disorder, SWSD).
In most cases, it is not known what causes the abnormality in the biological clocks of DSPS patients. DSPS tends to run in families, and a growing body of evidence suggests that the problem is associated with the hPer3 (human period 3) gene. There have been several documented cases of DSPS and non-24-hour sleep-wake syndrome developing after traumatic head injury
.
There have been a few cases of DSPS developing into non-24-hour sleep-wake syndrome
, a more severe and debilitating disorder in which the individual sleeps later each day. It has been suggested that, instead of (or perhaps in addition to) a reduced reaction to light in the morning, an abnormal over-sensitivity to light in the late evening might contribute to the odd non-circadian pattern.
DSPS is diagnosed by a clinical interview, actigraphic monitoring and/or a sleep diary
kept by the patient for at least three weeks. When polysomnography
is also used, it is primarily for the purpose of ruling out other disorders such as narcolepsy
or sleep apnea. If a person can, on her/his own with just the help of alarm clocks and will-power, adjust to a daytime schedule, the diagnosis is not given.
DSPS is frequently misdiagnosed or dismissed. It has been named as one of the sleep disorders most commonly misdiagnosed as a primary psychiatric disorder.See also subsequent:
* DSPS is often confused with: psychophysiological insomnia; depression
; psychiatric disorders such as schizophrenia
, ADHD or ADD; other sleep disorders; or school refusal
. Practitioners of sleep medicine
point out the dismally low rate of accurate diagnosis of the disorder, and have often asked for better physician education on sleep disorders.
Before starting DSPS treatment, patients are often asked to spend at least a week sleeping regularly, without napping, at the times when the patient is most comfortable. It is important for patients to start treatment well-rested.
Treatments that have been reported in the medical literature include:
Light therapy
(phototherapy) with a full spectrum lamp or portable visor, usually 10,000 lux
for 30–90 minutes at the patient's usual time of spontaneous awakening, or shortly before (but not long before), which is in accordance with the phase response curve
(PRC) for light. The use of an LED light therapy device can reduce this to 15–30 minutes. Sunlight can also be used. Only experimentation, preferably with specialist help, will show how great an advance is possible and comfortable. For maintenance, some patients must continue the treatment indefinitely, some may reduce the daily treatment to 15 minutes, others may use the lamp, for example, just a few days a week or just every third week. Whether the treatment is successful is highly individual. Light therapy generally requires adding some extra time to the patient's morning routine. Patients with a family history of macular degeneration
are advised to consult with an eye doctor. The use of exogenous melatonin administration (see below) in conjunction with light therapy is common.
Dim lights in the evening, sometimes called darkness therapy. Just as bright light upon awakening should advance one's sleep-phase, bright light in the evening and night delays it (see the PRC). One might be advised to keep lights dim the last hours before bedtime and even wear sunglasses or amber-colored goggles. Attaining an earlier sleep onset, in a dark room with eyes closed, effectively blocks a period of phase-delaying light. An understanding of this is a motivating factor in treatment.
Chronotherapy
, which is intended to reset the circadian clock by manipulating bedtimes. Often, chronotherapy must be repeated every few months to maintain results, and its safety is uncertain. It can be one of two types. The most common consists of going to bed two or more hours later each day for several days until the desired bedtime is reached. A modified chronotherapy (Thorpy, 1988) is called controlled sleep deprivation with phase advance, SDPA. One stays awake one whole night and day, then goes to bed 90 minutes earlier than usual and maintains the new bedtime for a week. This process is repeated weekly until the desired bedtime is reached.
Melatonin
taken an hour or so before usual bedtime may induce sleepiness.
Taken this late, it does not, of itself, affect circadian rhythms, but a decrease in exposure to light in the evening is helpful in establishing an earlier pattern. In accordance with its phase response curve (PRC), a very small dose of melatonin can also, or instead, be taken some hours earlier as an aid to resetting the body clock; it must then be so small as to not induce excessive sleepiness.
Side effects of melatonin may include disturbance of sleep, nightmares, daytime sleepiness and depression, though the current tendency to use lower doses has decreased such complaints. Large doses of melatonin can even be counterproductive: Lewy et al. provide support to the "idea that too much melatonin may spill over onto the wrong zone of the melatonin phase-response curve." The long-term effects of melatonin administration have not been examined. In some countries the hormone is available only by prescription or not at all. In the United States and Canada, melatonin is freely available as a dietary supplement. The prescription drug Rozerem (ramelteon
) is a melatonin analogue that selectively binds to the melatonin MT1 and MT2 receptors
and, hence, has the possibility of being effective in the treatment of DSPS.
A review by a US government agency found little difference between melatonin and placebo for most primary and secondary sleep disorders. The one exception, where melatonin is effective, is the "circadian abnormality" DSPS.
Cannabis
has been suggested as an aid to combat DSPS. However, no research has yet been done that shows cannabis works in DSPS. Sleep onset is affected by the two primary cannabinoids
. THC, Δ9-Tetrahydrocannabinol
, dramatically increased melatonin production in some subjects in a small study in 1986 where the authors state that "[t]hese preliminary results are difficult to interpret". An older study showed that CBD, cannabidiol
, was effective in helping insomniacs sleep. Several studies have shown that acute administration of THC decreases sleep latency, and is associated with reports of greater ease in getting to sleep. Heavy cannabis use can lead to decreased levels of REM sleep and increased levels of slow-wave sleep
along with reduced mental function the next morning. However, 5 mg doses of THC and CBD have been shown not to have these effects.
Modafinil
(Provigil) is approved in the US for treatment of shift-work sleep disorder, which shares some characteristics with DSPS, and a number of clinicians are prescribing it for DSPS patients. Modafinil does not deal with underlying causes of DSPS, but it may improve a sleep-deprived patient's quality of life. Taking modafinil less than 12 hours before the desired sleep onset time will likely exacerbate the symptoms by delaying the sleep/wake cycle.
Trazodone
successfully treated DSPS in one elderly man.
Vitamin B12
was, in the 1990s, suggested as a remedy for DSPS/DSPD, and can still be found to be recommended by many sources. Several case reports were published. However, a review for the American Academy of Sleep Medicine
in 2007 concluded that no benefit was seen from this treatment.
A strict schedule and good sleep hygiene
are essential in maintaining any good effects of treatment. With treatment, some people with mild DSPS may sleep and function well with an early sleep schedule. Caffeine
and other stimulant drugs to keep a person awake during the day may not be necessary, and should be avoided in the afternoon and evening, in accordance with good sleep hygiene. A chief difficulty of treating DSPS is in maintaining an earlier schedule after it has been established. Inevitable events of normal life, such as staying up late for a celebration or having to stay in bed with an illness, tend to reset the sleeping schedule to its intrinsic late times.
. Follow-up showed that over 90% had relapsed to pretreatment sleeping patterns within the year, 28.8% reporting that the relapse occurred within one week. The milder cases retained changes significantly longer than the more severe cases.
Working the evening or night shift
, or working at home, makes DSPS less of an obstacle for some. Many of these people do not describe their pattern as a "disorder". Some DSPS individuals nap, even taking 4–5 hours of sleep in the morning and 4–5 in the evening. DSPS-friendly careers can include security work, work in theater, the entertainment industry, hospitality work in restaurants, hotels or bars, call center work, nursing, taxi or truck driving, the media, and freelance writing, translation, IT work, or medical transcription
.
Some people with the disorder are unable to adapt to earlier sleeping times, even after many years of treatment. Sleep researchers have proposed that the existence of untreatable cases of DSPS be formally recognized as a "sleep-wake schedule disorder disability", an invisible disability
.
Rehabilitation
for DSPS patients includes acceptance
of the condition, and choosing a career that allows late sleeping times, or running their own home business because it allows flexible hours. In a few schools and universities, students with DSPS have been able to arrange to take exams at times of day when their concentration levels may be good.
In the United States, the Americans with Disabilities Act requires that employers make reasonable accommodations for employees with sleeping disorders. In the case of DSPS, this may require that the employer accommodate later working hours for jobs normally performed on a "9-to-5" work schedule.
As DSPS is so little-known and so misunderstood, support group
s may be important for information and self-acceptance.
People with DSPS who force themselves to live on a normal 9-5 day "are not often successful and may develop physical and psychological complaints during waking hours, i.e. sleepiness, fatigue, headache, decreased appetite, or depressed mood. Patients with [Circadian Rhythm Sleep Disorders] often have difficulty maintaining ordinary social lives, and some of them lose their jobs or fail to attend school."
or other psychological problems, about the same proportion as among patients with chronic insomnia. According to the ICSD
:
A direct neurochemical relationship between sleep mechanisms and depression is another possibility. DSPS may cause excessive or inappropriate production of melatonin. Serotonin
, a mood regulator, is a precursor to melatonin. As a result, increased endogenous melatonin production can deplete serotonin levels and may cause depression
It is conceivable that DSPS often has a major role in causing depression because it can be such a stressful and misunderstood disorder. A recent study from the University of California, San Diego
found no association of bipolar disorder
(history of mania) with DSPS, and it states that there may be
The fact that half of DSPS patients are not depressed indicates that DSPS is not merely a symptom of depression. Sleep researcher M. Terman has suggested that those who follow their internal circadian clocks may be less likely to suffer from depression than those trying to live on a different schedule.
DSPS patients who also suffer from depression may be best served by seeking treatment for both problems. There is some evidence that effectively treating DSPS can improve the patient's mood and make antidepressants more effective.
Vitamin D
deficiency has been linked to depression. As it is a condition which comes from lack of exposure to sunlight, anyone who does not get enough sunlight exposure during the daylight hours could be at risk.
, "disability" is defined as a "physical or mental impairment that substantially limits one or more major life activities". "Sleeping" is defined as a "major life activity" in § 12102(2)(a) of the statute.
Circadian rhythm sleep disorder
Circadian rhythm sleep disorders are a family of sleep disorders affecting, among other things, the timing of sleep. People with circadian rhythm sleep disorders are unable to sleep and wake at the times required for normal work, school, and social needs. They are generally able to get enough sleep...
, a chronic disorder of the timing of sleep, peak period of alertness, the core body temperature rhythm, hormonal and other daily rhythms, compared to the general population and relative to societal requirements. People with DSPS generally fall asleep some hours after midnight and have difficulty waking up in the morning.
Often, people with the disorder report that they cannot sleep until early morning, but fall asleep at about the same time every "night". Unless they have another sleep disorder
Sleep disorder
A sleep disorder, or somnipathy, is a medical disorder of the sleep patterns of a person or animal. Some sleep disorders are serious enough to interfere with normal physical, mental and emotional functioning...
such as sleep apnea
Sleep apnea
Sleep apnea is a sleep disorder characterized by abnormal pauses in breathing or instances of abnormally low breathing, during sleep. Each pause in breathing, called an apnea, can last from a few seconds to minutes, and may occur 5 to 30 times or more an hour. Similarly, each abnormally low...
in addition to DSPS, patients can sleep well and have a normal need for sleep. Therefore, they find it very difficult to wake up in time for a typical school or work day. If, however, they are allowed to follow their own schedules, e.g. sleeping from 4 a.m. to noon, they sleep soundly, awaken spontaneously, and do not experience excessive daytime sleepiness
Excessive daytime sleepiness
Excessive daytime sleepiness is characterized by persistent sleepiness, and often a general lack of energy, even after apparently adequate night time sleep...
.
The syndrome usually develops in early childhood or adolescence. An adolescent version disappears in adolescence or early adulthood; otherwise DSPS is a lifelong condition. Depending on the severity, it can be to a greater or lesser degree treatable. Prevalence among adults, equally distributed among women and men, is approximately 0.15%, or 3 in 2,000.
DSPS was first formally described in 1981 by Dr. Elliot D. Weitzman and others at Montefiore Medical Center
Montefiore Medical Center
Montefiore Medical Center, in the Bronx, New York, is the University Hospital for the Albert Einstein College of Medicine. The hospital, named for Moses Montefiore, is one of the 50 largest employers in New York State . In 2011, Montefiore Medical Center was ranked as #6 of the 180 New York City...
. It is responsible for 7–10% of patient complaints of chronic insomnia
Insomnia
Insomnia is most often defined by an individual's report of sleeping difficulties. While the term is sometimes used in sleep literature to describe a disorder demonstrated by polysomnographic evidence of disturbed sleep, insomnia is often defined as a positive response to either of two questions:...
. However, as few doctors are aware of it, it often goes untreated or is treated inappropriately; DSPS is often misdiagnosed as primary insomnia
Insomnia
Insomnia is most often defined by an individual's report of sleeping difficulties. While the term is sometimes used in sleep literature to describe a disorder demonstrated by polysomnographic evidence of disturbed sleep, insomnia is often defined as a positive response to either of two questions:...
or as a psychiatric condition. At its most severe and inflexible, it is an invisible disability
Invisible disability
Invisible disabilities are disabilities that are not immediately apparent. Some people with visual or auditory disabilities who do not wear glasses or hearing aids, or discreet hearing aids, may not be obviously disabled. Some people who have vision loss may wear contacts...
.
Definition
According to the International Classification of Sleep DisordersInternational Classification of Sleep Disorders
The International Classification of Sleep Disorders is "a primary diagnostic, epidemiological and coding resource for clinicians and researchers in the field of sleep and sleep medicine."...
(ICSD), the circadian rhythm sleep disorders share a common underlying chronophysiologic basis:
The ICSD (page 128-133) diagnostic criteria for delayed sleep-phase syndrome are:
Some people with the abnormality adapt their lives to the delayed sleep phase, avoiding common business hours (e.g., 9 a.m. to 5 p.m.) as much as possible. They have the disorder, but for them it is not a disability. The ICSD's severity criteria, all of them "over at least a one-month period", are:
- Mild: Two hour delay associated with little or mild impairment of social or occupational functioning.
- Moderate: Three hour delay associated with moderate impairment.
- Severe: Four hour delay associated with severe impairment.
Some features of DSPS which distinguish it from other sleep disorders are:
- People with DSPS have at least a normal—and often much greater than normal—ability to sleep during the morning, and sometimes in the afternoon as well. In contrast, those with chronic insomnia do not find it much easier to sleep during the morning than at night.
- People with DSPS fall asleep at more or less the same time every night, and sleep comes quite rapidly if the person goes to bed near the time he or she usually falls asleep. Young children with DSPS resist going to bed before they are sleepy, but the bedtime struggles disappear if they are allowed to stay up until the time they usually fall asleep.
- DSPS patients can sleep well and regularly when they can follow their own sleep schedule, e.g. on weekends and during vacations.
- DSPS is a chronic condition. Symptoms must have been present for at least one month before a diagnosis of DSPS can be made.
Attempting to force oneself onto daytime society's schedule with DSPS has been compared to constantly living with 6 hours of jet lag
Jet lag
Jet lag, medically referred to as desynchronosis, is a physiological condition which results from alterations to the body's circadian rhythms; it is classified as one of the circadian rhythm sleep disorders...
; the disorder has, in fact, been referred to as "social jet lag". Often, sufferers manage only a few hours sleep a night during the working week, then compensate by sleeping until the afternoon on weekends. Sleeping in on weekends, and/or taking long naps during the day, may give people with the disorder relief from daytime sleepiness but may also perpetuate the late sleep phase.
People with DSPS can be called extreme night owls
Night owl (person)
Night owl is a term used to describe a person who tends to stay up until late at night. Another name for a night owl is evening person.The opposite of a night owl is an early bird, a lark as opposed to owl, someone who tends to begin sleeping at a time that is considered early and also wakes early...
. They feel most alert and say they function best and are most creative in the evening and at night. DSPS patients cannot simply force themselves to sleep early. They may toss and turn for hours in bed, and sometimes not sleep at all, before reporting to work or school. Less extreme and more flexible night owls, and indeed morning larks, are within the normal chronotype
Chronotype
Chronotype is an attribute of animals, including human beings, reflecting at what time of the day their physical functions are active, change or reach a certain level...
spectrum.
By the time DSPS patients seek medical help, they usually have tried many times to change their sleeping schedule. Failed tactics to sleep at earlier times may include maintaining proper sleep hygiene
Sleep hygiene
Sleep hygiene can be defined as the controlling of "all behavioural and environmental factors that precede sleep and may interfere with sleep." It is the practice of following guidelines in an attempt to ensure more restful, effective sleep which can promote daytime alertness and help treat or...
, relaxation technique
Relaxation technique
A relaxation technique is any method, process, procedure, or activity that helps a person to relax; to attain a state of increased calmness; or otherwise reduce levels of anxiety, stress or anger...
s, early bedtimes, hypnosis
Hypnosis
Hypnosis is "a trance state characterized by extreme suggestibility, relaxation and heightened imagination."It is a mental state or imaginative role-enactment . It is usually induced by a procedure known as a hypnotic induction, which is commonly composed of a long series of preliminary...
, alcohol
Alcoholic beverage
An alcoholic beverage is a drink containing ethanol, commonly known as alcohol. Alcoholic beverages are divided into three general classes: beers, wines, and spirits. They are legally consumed in most countries, and over 100 countries have laws regulating their production, sale, and consumption...
, sleeping pills, dull reading, and home remedies
Home remedy
A home remedy is a treatment to cure a disease or ailment that employs certain spices, vegetables, or other common items. Home remedies may or may not have medicinal properties that treat or cure the disease or ailment in question, as they are typically passed along by laypersons...
. DSPS patients who have tried using sedatives at night often report that the medication makes them feel tired or relaxed, but that it fails to induce sleep. They often have asked family members to help wake them in the morning, or they have used several alarm clock
Alarm clock
An alarm clock is a clock that is designed to make a loud sound at a specific time. The primary use of these clocks is to awaken people from their night's sleep or short naps; they are sometimes used for other reminders as well. To stop the sound, a button or handle on the clock is pressed; but...
s. As the syndrome occurs in childhood and is most common in adolescence, it is often the patient's parents who initiate seeking help, after great difficulty waking their child in time for school.
The current formal name established in the second edition of the International Classification of Sleep Disorders is circadian rhythm sleep disorder, delayed sleep phase type; the preferred common name is delayed sleep-phase disorder.
Prevalence
About 0.15% of adults, three in 2,000, have DSPS. Using the strict ICSD diagnostic criteria, a random study in 1993 of 7700 adults (aged 18–67) in Norway estimated the prevalence of DSPS at 0.17%. A similar study of 1525 adults (aged 15–59) in Japan estimated its prevalence at 0.13%.A marked delay of sleep patterns is a normal feature of the development of adolescent humans. According to Mary Carskadon
Mary Carskadon
Mary A. Carskadon, Ph.D., is a Professor in the Department of Psychiatry and Human Behavior at the Warren Alpert Medical School of Brown University. She is also the Director of the at E.P. Bradley Hospital. She is considered to be an expert on sleep and circadian rhythms during childhood and...
, both circadian phase and homeostasis
Homeostasis
Homeostasis is the property of a system that regulates its internal environment and tends to maintain a stable, constant condition of properties like temperature or pH...
(the accumulation of sleep pressure during the wake period) contribute to a DSPS-like condition in post-pubertal as compared to pre-pubertal adolescents.
Physiology
DSPS is a disorder of the body's timing system—the biological clock. Individuals with DSPS might have an unusually long circadianCircadian rhythm
A circadian rhythm, popularly referred to as body clock, is an endogenously driven , roughly 24-hour cycle in biochemical, physiological, or behavioural processes. Circadian rhythms have been widely observed in plants, animals, fungi and cyanobacteria...
cycle, might have a reduced response to the re-setting effect of daylight on the body clock and/or may respond overly to the delaying effects of evening light and too little to the advancing effect of light earlier in the day. In support of the increased sensitivity to evening light hypothesis, "the percentage of melatonin suppression by a bright light stimulus of 1,000 lux administered 2 hours prior to the melatonin peak has been reported to be greater in 15 DSPS patients than in 15 controls."
People with normal circadian systems can generally fall asleep quickly at night if they slept too little the night before. Falling asleep earlier will in turn automatically help to advance their circadian clocks due to decreased light exposure in the evening. In contrast, people with DSPS are unable to fall asleep before their usual sleep time, even if they are sleep-deprived. Sleep deprivation does not reset the circadian clock of DSPS patients, as it does with normal people.
People with the disorder who try to live on a normal schedule cannot fall asleep at a "reasonable" hour and have extreme difficulty waking because their biological clocks are not in phase with that schedule. Normal people who do not adjust well to working a night shift have similar symptoms (diagnosed as shift-work sleep disorder, SWSD).
In most cases, it is not known what causes the abnormality in the biological clocks of DSPS patients. DSPS tends to run in families, and a growing body of evidence suggests that the problem is associated with the hPer3 (human period 3) gene. There have been several documented cases of DSPS and non-24-hour sleep-wake syndrome developing after traumatic head injury
Head injury
Head injury refers to trauma of the head. This may or may not include injury to the brain. However, the terms traumatic brain injury and head injury are often used interchangeably in medical literature....
.
There have been a few cases of DSPS developing into non-24-hour sleep-wake syndrome
Non-24-hour sleep-wake syndrome
Non-24-hour sleep-wake syndrome is a chronic circadian rhythm sleep disorder, classified within Chapter VI, Diseases of the Nervous System, in the ICD-10. It can be defined as "a chronic steady pattern comprising one- to two-hour daily delays in sleep onset and wake times in an individual living...
, a more severe and debilitating disorder in which the individual sleeps later each day. It has been suggested that, instead of (or perhaps in addition to) a reduced reaction to light in the morning, an abnormal over-sensitivity to light in the late evening might contribute to the odd non-circadian pattern.
Diagnosis
Sleep diary
A sleep diary is a record of an individual's sleeping and waking times with related information, usually over a period of several weeks. It is self-reported or can be recorded by a care-giver....
kept by the patient for at least three weeks. When polysomnography
Polysomnography
Polysomnography , also known as a sleep study, is a multi-parametric test used in the study of sleep and as a diagnostic tool in sleep medicine. The test result is called a polysomnogram, also abbreviated PSG...
is also used, it is primarily for the purpose of ruling out other disorders such as narcolepsy
Narcolepsy
Narcolepsy is a chronic sleep disorder, or dyssomnia, characterized by excessive sleepiness and sleep attacks at inappropriate times, such as while at work. People with narcolepsy often experience disturbed nocturnal sleep and an abnormal daytime sleep pattern, which often is confused with insomnia...
or sleep apnea. If a person can, on her/his own with just the help of alarm clocks and will-power, adjust to a daytime schedule, the diagnosis is not given.
DSPS is frequently misdiagnosed or dismissed. It has been named as one of the sleep disorders most commonly misdiagnosed as a primary psychiatric disorder.See also subsequent:
* DSPS is often confused with: psychophysiological insomnia; depression
Clinical depression
Major depressive disorder is a mental disorder characterized by an all-encompassing low mood accompanied by low self-esteem, and by loss of interest or pleasure in normally enjoyable activities...
; psychiatric disorders such as schizophrenia
Schizophrenia
Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...
, ADHD or ADD; other sleep disorders; or school refusal
School refusal
School refusal is a term originally used in the United Kingdom to describe refusal to attend school, due to emotional distress. School refusal differs from truancy in that children with school refusal feel anxiety or fear towards school, whereas truant children generally have no feelings of fear...
. Practitioners of sleep medicine
Sleep medicine
Sleep medicine is a medical specialty or subspecialty devoted to the diagnosis and therapy of sleep disturbances and disorders. From the middle of the 20th century, research has provided increasing knowledge and answered many questions about sleep-wake functioning. The rapidly evolving field has...
point out the dismally low rate of accurate diagnosis of the disorder, and have often asked for better physician education on sleep disorders.
Management
Treatment, a set of management techniques, is specific to DSPS. It is different from treatment of insomnia, and recognizes the patients' ability to sleep well on their own schedules, while addressing the timing problem. Success, if any, may be partial; for example, a patient who normally awakens at noon may only attain a wake time of 10 or 10:30 with treatment and follow-up. Being consistent with the treatment is paramount.Before starting DSPS treatment, patients are often asked to spend at least a week sleeping regularly, without napping, at the times when the patient is most comfortable. It is important for patients to start treatment well-rested.
Treatments that have been reported in the medical literature include:
Light therapy
Light therapy
Light therapy or phototherapy consists of exposure to daylight or to specific wavelengths of light using lasers, light-emitting diodes, fluorescent lamps, dichroic lamps or very bright, full-spectrum light, usually controlled with various devices...
(phototherapy) with a full spectrum lamp or portable visor, usually 10,000 lux
Lux
The lux is the SI unit of illuminance and luminous emittance, measuring luminous flux per unit area. It is used in photometry as a measure of the intensity, as perceived by the human eye, of light that hits or passes through a surface...
for 30–90 minutes at the patient's usual time of spontaneous awakening, or shortly before (but not long before), which is in accordance with the phase response curve
Phase response curve
A phase response curve illustrates the transient change in the cycle period of an oscillation induced by a perturbation as a function of the phase at which it is received...
(PRC) for light. The use of an LED light therapy device can reduce this to 15–30 minutes. Sunlight can also be used. Only experimentation, preferably with specialist help, will show how great an advance is possible and comfortable. For maintenance, some patients must continue the treatment indefinitely, some may reduce the daily treatment to 15 minutes, others may use the lamp, for example, just a few days a week or just every third week. Whether the treatment is successful is highly individual. Light therapy generally requires adding some extra time to the patient's morning routine. Patients with a family history of macular degeneration
Macular degeneration
Age-related macular degeneration is a medical condition which usually affects older adults and results in a loss of vision in the center of the visual field because of damage to the retina. It occurs in “dry” and “wet” forms. It is a major cause of blindness and visual impairment in older adults...
are advised to consult with an eye doctor. The use of exogenous melatonin administration (see below) in conjunction with light therapy is common.
Dim lights in the evening, sometimes called darkness therapy. Just as bright light upon awakening should advance one's sleep-phase, bright light in the evening and night delays it (see the PRC). One might be advised to keep lights dim the last hours before bedtime and even wear sunglasses or amber-colored goggles. Attaining an earlier sleep onset, in a dark room with eyes closed, effectively blocks a period of phase-delaying light. An understanding of this is a motivating factor in treatment.
Chronotherapy
Chronotherapy
People who suffer from delayed sleep phase syndrome are generally unable to reset their circadian rhythm by moving their bedtime and rising time earlier...
, which is intended to reset the circadian clock by manipulating bedtimes. Often, chronotherapy must be repeated every few months to maintain results, and its safety is uncertain. It can be one of two types. The most common consists of going to bed two or more hours later each day for several days until the desired bedtime is reached. A modified chronotherapy (Thorpy, 1988) is called controlled sleep deprivation with phase advance, SDPA. One stays awake one whole night and day, then goes to bed 90 minutes earlier than usual and maintains the new bedtime for a week. This process is repeated weekly until the desired bedtime is reached.
Melatonin
Melatonin
Melatonin , also known chemically as N-acetyl-5-methoxytryptamine, is a naturally occurring compound found in animals, plants, and microbes...
taken an hour or so before usual bedtime may induce sleepiness.
Side effects of melatonin may include disturbance of sleep, nightmares, daytime sleepiness and depression, though the current tendency to use lower doses has decreased such complaints. Large doses of melatonin can even be counterproductive: Lewy et al. provide support to the "idea that too much melatonin may spill over onto the wrong zone of the melatonin phase-response curve." The long-term effects of melatonin administration have not been examined. In some countries the hormone is available only by prescription or not at all. In the United States and Canada, melatonin is freely available as a dietary supplement. The prescription drug Rozerem (ramelteon
Ramelteon
Ramelteon, marketed as Rozerem by Takeda Pharmaceuticals North America, is the first in a new class of sleep agents that selectively binds to the MT1 and MT2 receptors in the suprachiasmatic nucleus , instead of binding to GABA A receptors, such as with drugs like zolpidem, eszopiclone, and...
) is a melatonin analogue that selectively binds to the melatonin MT1 and MT2 receptors
Melatonin receptor
A melatonin receptor is a G protein-coupled receptor which binds melatonin.Three types of melatonin receptor have been cloned. The MT1 and MT2 receptor subtypes are present in humans and other mammals, while an additional melatonin receptor subtype MT3 has been identified in amphibia and...
and, hence, has the possibility of being effective in the treatment of DSPS.
A review by a US government agency found little difference between melatonin and placebo for most primary and secondary sleep disorders. The one exception, where melatonin is effective, is the "circadian abnormality" DSPS.
Cannabis
Cannabis
Cannabis is a genus of flowering plants that includes three putative species, Cannabis sativa, Cannabis indica, and Cannabis ruderalis. These three taxa are indigenous to Central Asia, and South Asia. Cannabis has long been used for fibre , for seed and seed oils, for medicinal purposes, and as a...
has been suggested as an aid to combat DSPS. However, no research has yet been done that shows cannabis works in DSPS. Sleep onset is affected by the two primary cannabinoids
Cannabinoids
Cannabinoids are a class of chemical compounds that include the phytocannabinoids , and chemical compounds that mimic the actions of phytocannabinoids or have a similar structure...
. THC, Δ9-Tetrahydrocannabinol
Tetrahydrocannabinol
Tetrahydrocannabinol , also known as delta-9-tetrahydrocannabinol , Δ1-THC , or dronabinol, is the main chemical psychoactive substance found in the cannabis plant. It was first isolated in 1964. In pure form, it is a glassy solid when cold, and becomes viscous and sticky if warmed...
, dramatically increased melatonin production in some subjects in a small study in 1986 where the authors state that "[t]hese preliminary results are difficult to interpret". An older study showed that CBD, cannabidiol
Cannabidiol
Cannabidiol is a cannabinoid found in Cannabis. It is a major constituent of the plant, representing up to 40% in its extracts.It has displayed sedative effects in animal tests...
, was effective in helping insomniacs sleep. Several studies have shown that acute administration of THC decreases sleep latency, and is associated with reports of greater ease in getting to sleep. Heavy cannabis use can lead to decreased levels of REM sleep and increased levels of slow-wave sleep
Slow-wave sleep
Slow-wave sleep , often referred to as deep sleep, consists of stages 3 and 4 of non-rapid eye movement sleep, according to the Rechtschaffen & Kales standard of 1968. As of 2008, the American Academy of Sleep Medicine has discontinued the use of stage 4, such that the previous stages 3 and 4 now...
along with reduced mental function the next morning. However, 5 mg doses of THC and CBD have been shown not to have these effects.
Modafinil
Modafinil
Modafinil is an analeptic drug manufactured by Cephalon, and is approved by the U.S. Food and Drug Administration for the treatment of narcolepsy, shift work sleep disorder, and excessive daytime sleepiness associated with obstructive sleep apnea...
(Provigil) is approved in the US for treatment of shift-work sleep disorder, which shares some characteristics with DSPS, and a number of clinicians are prescribing it for DSPS patients. Modafinil does not deal with underlying causes of DSPS, but it may improve a sleep-deprived patient's quality of life. Taking modafinil less than 12 hours before the desired sleep onset time will likely exacerbate the symptoms by delaying the sleep/wake cycle.
Trazodone
Trazodone
Trazodone is an antidepressant of the serotonin antagonist and reuptake inhibitor class. It is a phenylpiperazine compound...
successfully treated DSPS in one elderly man.
Vitamin B12
Vitamin B12
Vitamin B12, vitamin B12 or vitamin B-12, also called cobalamin, is a water-soluble vitamin with a key role in the normal functioning of the brain and nervous system, and for the formation of blood. It is one of the eight B vitamins...
was, in the 1990s, suggested as a remedy for DSPS/DSPD, and can still be found to be recommended by many sources. Several case reports were published. However, a review for the American Academy of Sleep Medicine
American Academy of Sleep Medicine
The American Academy of Sleep Medicine is a United States professional society for the medical subspecialty of sleep medicine. It was established in 1975. The AASM is the only professional society that is dedicated exclusively to the medical subspecialty of sleep medicine...
in 2007 concluded that no benefit was seen from this treatment.
A strict schedule and good sleep hygiene
Sleep hygiene
Sleep hygiene can be defined as the controlling of "all behavioural and environmental factors that precede sleep and may interfere with sleep." It is the practice of following guidelines in an attempt to ensure more restful, effective sleep which can promote daytime alertness and help treat or...
are essential in maintaining any good effects of treatment. With treatment, some people with mild DSPS may sleep and function well with an early sleep schedule. Caffeine
Caffeine
Caffeine is a bitter, white crystalline xanthine alkaloid that acts as a stimulant drug. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants...
and other stimulant drugs to keep a person awake during the day may not be necessary, and should be avoided in the afternoon and evening, in accordance with good sleep hygiene. A chief difficulty of treating DSPS is in maintaining an earlier schedule after it has been established. Inevitable events of normal life, such as staying up late for a celebration or having to stay in bed with an illness, tend to reset the sleeping schedule to its intrinsic late times.
Adaptation to late sleeping times
Long-term success rates of treatment have seldom been evaluated. However, experienced clinicians acknowledge that DSPS is extremely difficult to treat. One study of 61 DSPS patients with mean sleep onset at about 3 a.m. and mean waking time of about 11:30 a.m., was followed up with questionnaires to the subjects a year later. Good effect was seen during the 6-week treatment with a daily, very large dose (5 mg), of melatoninMelatonin
Melatonin , also known chemically as N-acetyl-5-methoxytryptamine, is a naturally occurring compound found in animals, plants, and microbes...
. Follow-up showed that over 90% had relapsed to pretreatment sleeping patterns within the year, 28.8% reporting that the relapse occurred within one week. The milder cases retained changes significantly longer than the more severe cases.
Working the evening or night shift
Night Shift
A night shift is either a group of workers who work during the night, or the period in which they work. See shift work.Night Shift may also refer to:* Night Shift , a fictional team of supervillains in the Marvel Universe...
, or working at home, makes DSPS less of an obstacle for some. Many of these people do not describe their pattern as a "disorder". Some DSPS individuals nap, even taking 4–5 hours of sleep in the morning and 4–5 in the evening. DSPS-friendly careers can include security work, work in theater, the entertainment industry, hospitality work in restaurants, hotels or bars, call center work, nursing, taxi or truck driving, the media, and freelance writing, translation, IT work, or medical transcription
Medical transcription
Medical transcription, also known as MT, is an allied health profession, which deals in the process of transcription, or converting voice-recorded reports as dictated by physicians and/or other healthcare professionals, into text format.-History:...
.
Some people with the disorder are unable to adapt to earlier sleeping times, even after many years of treatment. Sleep researchers have proposed that the existence of untreatable cases of DSPS be formally recognized as a "sleep-wake schedule disorder disability", an invisible disability
Invisible disability
Invisible disabilities are disabilities that are not immediately apparent. Some people with visual or auditory disabilities who do not wear glasses or hearing aids, or discreet hearing aids, may not be obviously disabled. Some people who have vision loss may wear contacts...
.
Rehabilitation
Physical medicine and rehabilitation
Physical medicine and rehabilitation , physiatry or rehabilitation medicine, is a branch of medicine that aims to enhance and restore functional ability and quality of life to those with physical impairments or disabilities. A physician having completed training in this field is referred to as a...
for DSPS patients includes acceptance
Acceptance
Acceptance is a person's agreement to experience a situation, to follow a process or condition without attempting to change it, protest, or exit....
of the condition, and choosing a career that allows late sleeping times, or running their own home business because it allows flexible hours. In a few schools and universities, students with DSPS have been able to arrange to take exams at times of day when their concentration levels may be good.
In the United States, the Americans with Disabilities Act requires that employers make reasonable accommodations for employees with sleeping disorders. In the case of DSPS, this may require that the employer accommodate later working hours for jobs normally performed on a "9-to-5" work schedule.
Impact on patients
Lack of public awareness of the disorder contributes to the difficulties experienced by people with DSPS, who are commonly stereotyped as undisciplined or lazy. Parents may be chastised for not giving their children acceptable sleep patterns, and schools and workplaces rarely tolerate chronically late, absent, or sleepy students and workers, failing to see them as having a chronic illness.As DSPS is so little-known and so misunderstood, support group
Support group
In a support group, members provide each other with various types of help, usually nonprofessional and nonmaterial, for a particular shared, usually burdensome, characteristic...
s may be important for information and self-acceptance.
People with DSPS who force themselves to live on a normal 9-5 day "are not often successful and may develop physical and psychological complaints during waking hours, i.e. sleepiness, fatigue, headache, decreased appetite, or depressed mood. Patients with [Circadian Rhythm Sleep Disorders] often have difficulty maintaining ordinary social lives, and some of them lose their jobs or fail to attend school."
Comorbidity
In the DSPS cases reported in the literature, about half of the patients have suffered from clinical depressionClinical depression
Major depressive disorder is a mental disorder characterized by an all-encompassing low mood accompanied by low self-esteem, and by loss of interest or pleasure in normally enjoyable activities...
or other psychological problems, about the same proportion as among patients with chronic insomnia. According to the ICSD
International Classification of Sleep Disorders
The International Classification of Sleep Disorders is "a primary diagnostic, epidemiological and coding resource for clinicians and researchers in the field of sleep and sleep medicine."...
:
A direct neurochemical relationship between sleep mechanisms and depression is another possibility. DSPS may cause excessive or inappropriate production of melatonin. Serotonin
Serotonin
Serotonin or 5-hydroxytryptamine is a monoamine neurotransmitter. Biochemically derived from tryptophan, serotonin is primarily found in the gastrointestinal tract, platelets, and in the central nervous system of animals including humans...
, a mood regulator, is a precursor to melatonin. As a result, increased endogenous melatonin production can deplete serotonin levels and may cause depression
It is conceivable that DSPS often has a major role in causing depression because it can be such a stressful and misunderstood disorder. A recent study from the University of California, San Diego
University of California, San Diego
The University of California, San Diego, commonly known as UCSD or UC San Diego, is a public research university located in the La Jolla neighborhood of San Diego, California, United States...
found no association of bipolar disorder
Bipolar disorder
Bipolar disorder or bipolar affective disorder, historically known as manic–depressive disorder, is a psychiatric diagnosis that describes a category of mood disorders defined by the presence of one or more episodes of abnormally elevated energy levels, cognition, and mood with or without one or...
(history of mania) with DSPS, and it states that there may be
The fact that half of DSPS patients are not depressed indicates that DSPS is not merely a symptom of depression. Sleep researcher M. Terman has suggested that those who follow their internal circadian clocks may be less likely to suffer from depression than those trying to live on a different schedule.
DSPS patients who also suffer from depression may be best served by seeking treatment for both problems. There is some evidence that effectively treating DSPS can improve the patient's mood and make antidepressants more effective.
Vitamin D
Vitamin D
Vitamin D is a group of fat-soluble secosteroids. In humans, vitamin D is unique both because it functions as a prohormone and because the body can synthesize it when sun exposure is adequate ....
deficiency has been linked to depression. As it is a condition which comes from lack of exposure to sunlight, anyone who does not get enough sunlight exposure during the daylight hours could be at risk.
United States
According to the Americans with Disabilities Act of 1990Americans with Disabilities Act of 1990
The Americans with Disabilities Act of 1990 is a law that was enacted by the U.S. Congress in 1990. It was signed into law on July 26, 1990, by President George H. W. Bush, and later amended with changes effective January 1, 2009....
, "disability" is defined as a "physical or mental impairment that substantially limits one or more major life activities". "Sleeping" is defined as a "major life activity" in § 12102(2)(a) of the statute.
See also
- Advanced sleep phase syndromeAdvanced sleep phase syndromeAdvanced sleep phase syndrome , also known as the advanced sleep-phase type of circadian rhythm sleep disorder, is a condition in which patients feel very sleepy and go to bed early in the evening and wake up very early in the morning Advanced sleep phase syndrome (ASPS), also known as the...
- ChronobiologyChronobiologyChronobiology is a field of biology that examines periodic phenomena in living organisms and their adaptation to solar- and lunar-related rhythms. These cycles are known as biological rhythms. Chronobiology comes from the ancient Greek χρόνος , and biology, which pertains to the study, or science,...
- Circadian rhythmCircadian rhythmA circadian rhythm, popularly referred to as body clock, is an endogenously driven , roughly 24-hour cycle in biochemical, physiological, or behavioural processes. Circadian rhythms have been widely observed in plants, animals, fungi and cyanobacteria...
- Evolutionary baggageEvolutionary baggageEvolutionary baggage is the part of the genome of a population that was advantageous in past individuals but is disadvantageous under the pressures exerted by natural selection today.-Origin:...
- InsomniaInsomniaInsomnia is most often defined by an individual's report of sleeping difficulties. While the term is sometimes used in sleep literature to describe a disorder demonstrated by polysomnographic evidence of disturbed sleep, insomnia is often defined as a positive response to either of two questions:...
- Non-24-hour sleep-wake syndromeNon-24-hour sleep-wake syndromeNon-24-hour sleep-wake syndrome is a chronic circadian rhythm sleep disorder, classified within Chapter VI, Diseases of the Nervous System, in the ICD-10. It can be defined as "a chronic steady pattern comprising one- to two-hour daily delays in sleep onset and wake times in an individual living...
- Irregular sleep-wake rhythmIrregular sleep-wake rhythmIrregular sleep–wake rhythm is a rare form of circadian rhythm sleep disorder. It is characterized by numerous naps throughout the 24-hour period, no main nighttime sleep episode and irregularity from day to day. Sufferers have no pattern of when they are awake or asleep, may have poor quality...
- Seasonal Affective DisorderSeasonal affective disorderSeasonal affective disorder , also known as winter depression, winter blues, summer depression, summer blues, or seasonal depression, is a mood disorder in which people who have normal mental health throughout most of the year experience depressive symptoms in the winter or summer, spring or autumn...
- Sleep inertiaSleep inertiaSleep inertia is a physiological state characterised by a decline in motor dexterity and a subjective feeling of grogginess immediately following an abrupt awakening. The impaired alertness may interfere with the ability to perform mental or physical tasks...
External links
- Australian DSPS fact sheet, PDF
- DSPS blog - Written by and for people with DSPS