Chronotherapy
Encyclopedia
People who suffer from delayed sleep phase syndrome
are generally unable to reset their circadian rhythm
by moving their bedtime and rising time earlier. In sleep phase chronotherapy, an attempt is made to move bedtime and rising time later and later each day, around the clock, until the person is sleeping on a normal schedule.
While this technique can provide temporary respite from sleep deprivation
, patients may find the desired sleep and waketimes slip. The desired pattern can only be maintained by following a strictly disciplined timetable for sleeping and rising.
Sometimes, although extremely infrequently, "reverse" chronotherapy – i.e., gradual movements of bedtime and rising time earlier each day – has been used in treatment of patients with abnormally short circadian rhythms, in an attempt to move their bedtimes to later times of the day. Because circadian rhythms substantially shorter than 24 hours are extremely rare, this type of chronotherapy has remained largely experimental.
Chronotherapy has been known to cause Non-24-hour sleep-wake syndrome
in at least three recorded cases, as reported in the New England Journal of Medicine in 1992. Animal studies have suggested that such lengthening could "slow the intrinsic rhythm of the body clock to such an extent that the normal 24-hour day no longer lies within its range of entrainment."
Delayed sleep phase syndrome
Delayed sleep-phase syndrome , also known as delayed sleep-phase disorder or delayed sleep-phase type , 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...
are generally unable to reset their circadian rhythm
Circadian 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...
by moving their bedtime and rising time earlier. In sleep phase chronotherapy, an attempt is made to move bedtime and rising time later and later each day, around the clock, until the person is sleeping on a normal schedule.
Example
Here's an example of how chronotherapy could work over a week's course of treatment, with the patient going to sleep 3 hours later every day until the desired sleep and waketime is reached. (Shifting the sleep phase by 3 hours per day may not always be possible; shorter increments of 1–2 hours are needed in such cases.)- Day 1: sleep 04:00 to 12:00
- Day 2: sleep 07:00 to 15:00
- Day 3: sleep 10:00 to 18:00
- Day 4: sleep 13:00 to 21:00
- Day 5: sleep 16:00 to 00:00
- Day 6: sleep 19:00 to 03:00
- Day 7 to 13: sleep 22:00 to 06:00
- Day 14 and thereafter: sleep 23:00 to 07:00
While this technique can provide temporary respite from sleep deprivation
Sleep deprivation
Sleep deprivation is the condition of not having enough sleep; it can be either chronic or acute. A chronic sleep-restricted state can cause fatigue, daytime sleepiness, clumsiness and weight loss or weight gain. It adversely affects the brain and cognitive function. Few studies have compared the...
, patients may find the desired sleep and waketimes slip. The desired pattern can only be maintained by following a strictly disciplined timetable for sleeping and rising.
Reverse chronotherapy
A modified chronotherapy 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.Sometimes, although extremely infrequently, "reverse" chronotherapy – i.e., gradual movements of bedtime and rising time earlier each day – has been used in treatment of patients with abnormally short circadian rhythms, in an attempt to move their bedtimes to later times of the day. Because circadian rhythms substantially shorter than 24 hours are extremely rare, this type of chronotherapy has remained largely experimental.
Side effects
The safety of chronotherapy is not fully known. While chronotherapy has been successful for some, it is necessary to rigidly maintain the desired sleep/wake cycle thenceforth. Any deviation in schedule tends to allow the body clock to shift later again.Chronotherapy has been known to cause 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...
in at least three recorded cases, as reported in the New England Journal of Medicine in 1992. Animal studies have suggested that such lengthening could "slow the intrinsic rhythm of the body clock to such an extent that the normal 24-hour day no longer lies within its range of entrainment."