Most of us today adhere to a similar cycle of sleep. Staying awake through the day, we sleep through the night, when the absence of daylight makes outdoor activities impractical. This circadian rhythm is regulated by light sources in our environment, such as the Sun. The common practise of sleeping for just one continuous period daily - at night - is known as a monophasic sleep pattern and is a routine which humans have practised prior to the availability of artificial lighting, which today makes nocturnal activities more practical.
But with the rise of the “night shift” amongst shift workers in places such as hospitals and the haulage industry, normal sleep patterns can be shorter than normal and interrupted according to the diktats of the work schedule - resting can be a challenge!
Night shift workers will often adopt a polyphasic sleep pattern, which involves gaining sleep as schedules permit, in the form of naps during breaks. However, for many other professions besides, as well as other societies and even species, polyphasic sleep is an accepted way of life. Examples of polyphasic sleepers include:
Sailors - when long-distance rowing must be co-ordinated across a team of sailors, short bursts of sleep between physical effort provide some rest in situations where it is impractical for an entire crew to sleep throughout the night.
Haulage drivers - taking advantage of quiet roads at night, and frequently working in alternating shifts, haulage drivers must take sleep when it is safe. The irregularity of opportunities to sleep can lead to drivers opting for polyphasic sleep patterns in the form of naps (Moreno et al, 2003).1
In Spain and many South American countries, citizens will sleep twice each day - at night and through the uncomfortably high temperatures of the afternoon. This biphasic sleep pattern (sleeping twice) is commonly known as a siesta.
In the animal kingdom, sleep patterns focus on maximum survival chances rather than work schedules, so polyphasic sleep patterns are normal. Although cats are nocturnal, much of their sleep occurs at intervals throughout both the day and night, as so many other species.
Sleep Pattern Types
Humans’ current sleeping habits originate from previous centuries, when a dependence on sunlight made outdoor activities at night, such as agricultural work, difficult. Therefore, humans take advantage of low levels of light as an opportunity to sleep. In the 20th Century, however, technological advancements have lead to the ubiquity of artificial light, both indoors and outdoors, and central heating, meaning that nature no longer dictates sleep patterns in the way that it once did. As a result, in recent years, there has been a growing trend towards experimentation with polyphasic sleep patterns, with a view to finding an optimal pattern which will maximize performance when awake whilst minimising time spent sleeping. Some of these sleep patterns include:
Uberman: Described on online community website Everything2 user ‘PureDoxyk’ in 1998, the “Uberman” sleep schedule has attracted significant attention from people wanting to maximise their time spent awake. The Uberman cycle involves polyphasic sleep at 6 intervals each day - napping every 4 hours for 20 minutes at a time.2
Biphasic sleep patterns: This pattern involves sleeping twice per day. Although the siesta is an example of a biphasic sleep pattern, they need not consist of nocturnal sleep followed by an afternoon nap, and can include two sleeps at regular or irregular intervals.
Everyman - Also proposed by the creator of the Uberman schedule, the Everyman sleep schedule has spawned its own variations, but each consists of a “core” sleep period followed by a number of brief naps during the day. For example, the first Everyman sleep schedule created consisted of a core sleep of approximately 3 hours each night, with 3 shorter naps throughout the day, each 20 minutes in duration. This schedule provides for around 4 hours of sleep per day.3
Dymaxion - This sleep cycle was tested and named by the U.S. architect Buckminster Fuller (1895-1983). Fuller had a passion for his work wanted to maximise the time he had to devote to his interests, experimenting with what he termed the “dymaxion” sleep schedule. This polyphasic pattern consists of four half-hour naps taken equidistantly throughout the day, giving up to just two hours of sleep each day.
Many of these sleep schedules aim to reduce our dependence on sleep as much as possible. Before commencing one of these alternative patterns, remember that sleep is an essential activity, and numerous studies have identified unintended consequences of sleep loss.
Nonetheless, some research suggests that polyphasic sleep may be useful in some situations. Claudio Stampi (1989) studied the sleep patterns of 99 rowers participating in a race, and compared them to their performance whilst awake. Stampi found that the sailors would naturally adopt polyphasic sleep, taking short naps at intervals. Interestingly, he noted that the best performers enjoyed shorter naps and their overall sleep durations were among the shortest of the study sample (Stampi, 1989).4
Further research has suggested that naps may not just impact our physical performance, but cognitive abilities, too. In a simple memory test, participants were asked to remember a list of words and after a one hour interval, prompted to recall the words. During the interval, some participants remained awake whilst others took naps of varying lengths. Memory recall was found to benefit from naps during the interval, with even short naps just a few minutes in length affecting memory performance (Lahl et al, 2008).5
These findings suggest that sleep, as well as conscious rehearsal of information, can impact our memory recall abilities.
Researchers believe that a process known as “slow learning” takes place during sleep, as the findings of a study into participants’ responses to visual stimuli have also suggested (Mednick et al, 2002).6