Segmented sleep
Encyclopedia
Segmented sleep, also known as divided sleep, bimodal sleep pattern, or interrupted sleep, is a polyphasic
or biphasic sleep pattern where two or more periods of sleep are punctuated by a period of wakefulness.
In Western civilization before the Industrial Revolution, segmented sleep was the dominant form of human slumber since time immemorial, according to A. Roger Ekirch, a historian at Virginia Tech. Over the course of nearly two decades of research, Ekirch discovered extensive evidence of this sleep pattern in a wide variety of documents, dating from the ancient world until the nineteenth century. Typically, individuals slept in two discrete phases, bridged by an intervening period of wakefulness of up to an hour or more. Peasant
couples, who were often too tired after field labor to do much more than eat and go to sleep, awakened later to have sex. People also used this time to pray and reflect, and to interpret dream
s, which were more vivid at that hour than upon waking in the morning. This was also a favorite time for scholars and poets to write uninterrupted, whereas still others visited neighbors and engaged in petty crime.
The human circadian rhythm
regulates the human sleep-wake cycle of wakefulness during the day and sleep at night. Due to the modern use of electric lighting, most modern humans do not practice segmented sleep, which is a concern for some scientists. Superimposed on this basic rhythm is a secondary one of light sleep in the early afternoon (see siesta
) and quiet wakefulness in the early morning.
There is evidence from sleep research that this period of nighttime wakefulness, combined with a midday nap, results in greater alertness than a monophasic sleep-wake cycle. The brain exhibits high levels of the pituitary hormone
prolactin
during the period of nighttime wakefulness, which may contribute to the feeling of peace that many people associate with it. It is in many ways similar to the hypnogogic and hypnopompic
states which occur just before falling asleep and upon waking, respectively.
The modern assumption that consolidated sleep with no awakenings is the normal and correct way for human adults to sleep, may lead many people to approach their doctors with complaints of maintenance insomnia
or other sleep disorder
s. Their concerns might best be addressed by assurance that their sleep conforms to historically natural sleep patterns.
. First and second sleep are also the terms in the Romance languages
, as well as the Tiv of Nigeria
: In French, the common term was premier sommeil or premier somme; in Italian, primo sonno; in Latin, primo somno or comcubia nocte. There is no common word in English for the period of wakefulness between, apart from paraphrases such as first waking or when one wakes from his first sleep and the generic watch (in its old meaning of being awake). In French
an equivalent generic term is dorveille ("twixt sleep and wake").
Because members of modern industrialised societies, with late hours facilitated by electric lighting, mostly do not practice segmented sleep, they may misinterpret and mistranslate references to it in literature. Common interpretations of the term "first sleep" are "beauty sleep" and "early slumber". A reference to first sleep in the Odyssey
was translated as such in the 17th century, but universally mistranslated in the 20th.
Polyphasic sleep
Polyphasic sleep, a term coined by early 20th-century psychologist J.S. Szymanski, refers to the practice of sleeping multiple times in a 24-hour period—usually more than two, in contrast to biphasic sleep or monophasic sleep . It does not imply any particular sleep schedule...
or biphasic sleep pattern where two or more periods of sleep are punctuated by a period of wakefulness.
In Western civilization before the Industrial Revolution, segmented sleep was the dominant form of human slumber since time immemorial, according to A. Roger Ekirch, a historian at Virginia Tech. Over the course of nearly two decades of research, Ekirch discovered extensive evidence of this sleep pattern in a wide variety of documents, dating from the ancient world until the nineteenth century. Typically, individuals slept in two discrete phases, bridged by an intervening period of wakefulness of up to an hour or more. Peasant
Peasant
A peasant is an agricultural worker who generally tend to be poor and homeless-Etymology:The word is derived from 15th century French païsant meaning one from the pays, or countryside, ultimately from the Latin pagus, or outlying administrative district.- Position in society :Peasants typically...
couples, who were often too tired after field labor to do much more than eat and go to sleep, awakened later to have sex. People also used this time to pray and reflect, and to interpret dream
Dream
Dreams are successions of images, ideas, emotions, and sensations that occur involuntarily in the mind during certain stages of sleep. The content and purpose of dreams are not definitively understood, though they have been a topic of scientific speculation, philosophical intrigue and religious...
s, which were more vivid at that hour than upon waking in the morning. This was also a favorite time for scholars and poets to write uninterrupted, whereas still others visited neighbors and engaged in petty crime.
The human 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...
regulates the human sleep-wake cycle of wakefulness during the day and sleep at night. Due to the modern use of electric lighting, most modern humans do not practice segmented sleep, which is a concern for some scientists. Superimposed on this basic rhythm is a secondary one of light sleep in the early afternoon (see siesta
Siesta
A siesta is a short nap taken in the early afternoon, often after the midday meal. Such a period of sleep is a common tradition in some countries, particularly those where the weather is warm....
) and quiet wakefulness in the early morning.
There is evidence from sleep research that this period of nighttime wakefulness, combined with a midday nap, results in greater alertness than a monophasic sleep-wake cycle. The brain exhibits high levels of the pituitary hormone
Hormone
A hormone is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. In essence, it is a chemical messenger that transports a signal from one...
prolactin
Prolactin
Prolactin also known as luteotropic hormone is a protein that in humans is encoded by the PRL gene.Prolactin is a peptide hormone discovered by Henry Friesen...
during the period of nighttime wakefulness, which may contribute to the feeling of peace that many people associate with it. It is in many ways similar to the hypnogogic and hypnopompic
Hypnopompic
A hypnopompic state is the state of consciousness leading out of sleep, a term coined by the psychical researcher Frederic Myers. Its twin is the hypnagogic state at sleep onset; though often conflated, the two states are not identical...
states which occur just before falling asleep and upon waking, respectively.
The modern assumption that consolidated sleep with no awakenings is the normal and correct way for human adults to sleep, may lead many people to approach their doctors with complaints of maintenance 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 other 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...
s. Their concerns might best be addressed by assurance that their sleep conforms to historically natural sleep patterns.
Etymology
The two periods of night sleep were called "first sleep" (occasionally "dead sleep") and "second sleep" (or "morning sleep") in medieval EnglandEngland
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
. First and second sleep are also the terms in the Romance languages
Romance languages
The Romance languages are a branch of the Indo-European language family, more precisely of the Italic languages subfamily, comprising all the languages that descend from Vulgar Latin, the language of ancient Rome...
, as well as the Tiv of Nigeria
Nigeria
Nigeria , officially the Federal Republic of Nigeria, is a federal constitutional republic comprising 36 states and its Federal Capital Territory, Abuja. The country is located in West Africa and shares land borders with the Republic of Benin in the west, Chad and Cameroon in the east, and Niger in...
: In French, the common term was premier sommeil or premier somme; in Italian, primo sonno; in Latin, primo somno or comcubia nocte. There is no common word in English for the period of wakefulness between, apart from paraphrases such as first waking or when one wakes from his first sleep and the generic watch (in its old meaning of being awake). In French
French language
French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...
an equivalent generic term is dorveille ("twixt sleep and wake").
Because members of modern industrialised societies, with late hours facilitated by electric lighting, mostly do not practice segmented sleep, they may misinterpret and mistranslate references to it in literature. Common interpretations of the term "first sleep" are "beauty sleep" and "early slumber". A reference to first sleep in the Odyssey
Odyssey
The Odyssey is one of two major ancient Greek epic poems attributed to Homer. It is, in part, a sequel to the Iliad, the other work ascribed to Homer. The poem is fundamental to the modern Western canon, and is the second—the Iliad being the first—extant work of Western literature...
was translated as such in the 17th century, but universally mistranslated in the 20th.
See also
- Polyphasic sleepPolyphasic sleepPolyphasic sleep, a term coined by early 20th-century psychologist J.S. Szymanski, refers to the practice of sleeping multiple times in a 24-hour period—usually more than two, in contrast to biphasic sleep or monophasic sleep . It does not imply any particular sleep schedule...
- Why We Nap: Evolution, Chronobiology, and Functions of Polyphasic and Ultrashort Sleep (book)
- SiestaSiestaA siesta is a short nap taken in the early afternoon, often after the midday meal. Such a period of sleep is a common tradition in some countries, particularly those where the weather is warm....
- 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...
- SleepSleepSleep is a naturally recurring state characterized by reduced or absent consciousness, relatively suspended sensory activity, and inactivity of nearly all voluntary muscles. It is distinguished from quiet wakefulness by a decreased ability to react to stimuli, and is more easily reversible than...
Further reading
- Everett, Daniel L. (2008) Don't Sleep, there are Snakes, Pantheon BooksPantheon BooksPantheon Books is an American imprint with editorial independence that is part of the Knopf Doubleday Publishing Group.The current editor-in-chief at Pantheon Books is Dan Frank.-Overview:...
ISBN 978-0-375-42502-8 - Jean Verdon, Night in the Middle Ages, trans. George Holoch (2002). ISBN 026803656X.
External links
- Sleep We Have Lost: Pre-industrial Slumber in the British Isles
- Library of Congress Webcast - At Day's Close: Night In Times Past
- Slumber's Unexplored Landscape: People in traditional societies sleep in eye-opening ways
- New York Times, Richard A. Friedman, M.D., March 14, 2006, Wake Up and Smell the Savanna
- Coturnix, ScienceBlogs Includes image of original data, Wehr's experiment
- The science of sleep: Jessa Gamble on TED.com