The aim of this section is to share scientific articles on polyphasic and biphasic sleep in adult humans. Many of the studies have a short summary in hopes to ease the search process of people looking for specific points or claims. If you find an article about polyphasic sleep that is not included in this list, do not hesitate to contact the moderators on Reddit or the Discord.

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An ultra short episode of sleep is sufficient to promote declarative memory performance 
This paper shows that even short naps consisting only of light sleep are able to improve the declarative memory of people.

Circasemidian sleep propensity and the phase‐amplitude maintenance model of human sleep/wake regulation
The article talks about the biphasic and polyphasic nature of humans.

Concepts and models of sleep regulation: an overview

Field study of sleep and functional impairments in solo sailing races
During sailor races the participants slept polyphasically, but experienced functional impairments due to sleep loss. These people slept a much shorter total duration each day on their polyphasic schedules than they did when monophasic.

Homeostatic Regulation of REM Sleep in Humans During Extended Sleep
Subjects who were under an artificially shortened photoperiod of 10 hours (very long night) showed a tendency to switch to polyphasic sleep schedules.

In short photoperiods, human sleep is biphasic
The article presents evidence to show that when normal individuals switched from a normal 16-h photoperiod to an experimental 10-h photoperiod (very long night), their sleep sessions became longer and usually split into two symmetrical phases, lasting several hours, with a 1-3 h waking gap between sleeps.

Is sleep fundamentally different between mammalian species?
Proposes that humans might be naturally polyphasic sleepers, but that either societal pressure or issues with sustaining wakefulness for long periods of time caused humans to acquire a monophasic sleep pattern.

Mammalian Sleep Dynamics: How Diverse Features Arise from a Common Physiological Framework

By varying the homeostatic time constant which determines the rate of somnogen accumulation and clearance, or by varying the mean drive to the sleep-active ventrolateral preoptic area of the hypothalamus, provided by for example the SCN, human sleep became polyphasic.

Napping behavior during “spontaneous internal desynchronization^: sleep remains in synchrony with body temperature
This paper shows evidence for human sleep being polyphasic, or especially biphasic, under enforced bedrest.

Natural sleep and its seasonal variations in three pre-industrial societies
This paper discusses how napping patterns change throughout the world depending on the season.

Polyphasic sleep strategies improve prolonged sustained performance: A field study on 99 sailors


Segmented sleep in a nonelectric, small‐scale agricultural society in Madagascar
This article talks about an agricultural society in Madagascar, where they wake in the middle of the night for long enough to consider it a segmented pattern about 50% of the days with noticeable variation from gender, and they also have a nap ~90% of the days about an hour in length.

Segmented Sleep in Preindustrial Societies
The author of this letter criticizes the conclusions made in the article “Natural sleep and its seasonal variations in three pre-industrial societies”. He is arguing against the idea of latitudinal variation in sleep patterns, and provides evidence to support his position.

Sleep and Alertness During Alternating Monophasic and Polyphasic Rest-Activity Cycles
Forced splitting of sleep allowed people to sleep for shorter durations than when monophasic. This article provides information that it is possible to adapt to non-monophasic sleep patterns, but did not make claims regarding the cognitive performance or alertness of adapted polyphasic sleepers compared to monophasic ones.

Sleep and Circadian Rhythms in Space

This article makes the claim that short naps result in feelings of lethargy and lassitude, which leads to worse mental performance. However, motivation is enough to counter these negative effects.

Sleep disorders and depression: brief review of the literature, case report, and nonpharmacologic interventions for depression
This paper talks about the fact that elderly people usually have polyphasic sleep patterns.

Sleep in Healthy Elderly Subjects: A 24-Hour Ambulatory Polysomnographic Study
This article showed that elderly people often become polyphasic sleepers with fragmented sleep, and that undesired daytime naps were correlated with being unhealthy.

Sleep Inertia: Best Time Not to Wake Up?
This paper says that there were no particular times of day or night when the subject’s sleep was be interrupted, followed by them quickly regain full psychomotor and cognitive functions. The article speculates that long-term training in taking many short naps or sleeping polyphasically to replace the regular 7-8 h of monophasic sleep might result in people overcoming the negative effects from naps.

This article shows that biphasic sleepers had the best academic performance, while monophasic and polyphasic sleepers had around the same success rate for passing their midterm exams.

Sleep we have lost: pre-industrial slumber in the British Isles.
This article talks about the natural polyphasic sleep pattern in pre-industrial societies.

Temporal sleep patterns in adults using actigraph
Actigraphic analyses showed that from a sample of the adult subjects from São Paulo city 92% slept monophasically, 7% biphasically, and 1% polyphasically. The study claims that polyphasic and biphasic patterns may be associated with the ability for humans to fall asleep several times a day, ie. with a lack of social pressure.

The evolution of the sleep-wake cycle through the history of humanity. Influence of artificial light
This scientific paper talks about biphasic sleep being the natural sleep pattern for humans, and that the introduction of artificial light and societal pressure forced human sleep to become monophasic.

The nature of spontaneous sleep across adulthood
This study showed that when people are removed of the need to overcome the physiological sleep tendency (by doing only mundane tasks), they sleep polyphasically.

Timing of human sleep: recovery process gated by a circadian pacemaker.
In the two‐process model of sleep regulation (which puts forwards that a homeostatic process interacts with a process controlled by the circadian pacemaker) the frequency of sleep–wake changes are dependant upon the distance between the circadian thresholds which define sleep and wake. In simulations, reducing this interval induced polyphasic sleep.

Truck Drivers Sleep-Wake Time Arrangements
The article concludes that a strong social pressure, which in this case is the work schedule, can bring forth the occurrence of a polyphasic sleep pattern. Polyphasic sleep might in this case be used as a strategy to adapt to an irregular or otherwise taxing work schedule.

When the Human Circadian System is Caught Napping: Evidence for Endogenous Rhythms Close to 24 Hours

Master’s theses


Segmented Sleep in First-Century Roman Society

Bachelor’s theses

Losing Sleep: A Preliminary Investigation of the Cognitive Effects that Arise from Polyphasic Sleep Cycles

Psychological Impacts of Polyphasic Sleep

Sleep in the 21st Century: Impacts of Sleep Dysregulation on Health and Well-Being


Main author: Crimson

Page last updated: 23 September 2019