Biphasic Sleep: Should You Be Sleeping in Two Shifts?

Sleep is a crucial element of human health, and the amount of sleep a person needs changes with age. Just like many other bodily functions, sleep has patterns. With most sleep patterns, a person sleeps once a day, usually at night, while others are defined by several rest periods. However, the sleep pattern that is most typical in a population may not necessarily be the healthiest option for certain people.

This means that there is a number of people that report that they are not getting the sleep they need, regardless of the number of hours they have per night.

This article looks at the different kinds of sleep patterns known to sleep scientists, and how they impact peoples’ health and sleep hygiene.

Some quick facts on biphasic and polyphasic sleep

  • A person’s internal circadian rhythm is responsible for their sleep-wake cycle.
  • A monophasic sleep pattern is when an individual sleeps once per day, typically for 8 or so hours a night.
  • A biphasic sleep pattern is when someone sleeps twice per day, sometimes referred to as a siesta sleeping pattern.
  • A polyphasic sleep pattern is when a person sleeps for periods of time throughout the day.

What is Biphasic Sleep?

You most likely know at least one biphasic sleeper, without even knowing it. Maybe you even are one yourself. Biphasic sleep is a specific type of sleep pattern that is also called bimodal sleep, diphasic sleep, segmented sleep, or divided sleep.

Simply put, biphasic sleep describes sleep routines that include a person sleeping in two separate segments throughout the day. One such pattern could be to sleep for a few hours during nighttime hours and taking a midday nap.

The majority of people are monophasic sleepers by nature. Monophasic sleep patterns include just one sleep phase, generally during nighttime hours. That may not always have been the case, however. It’s believed that today’s custom of sleeping between six to eight hours in one session during the night, may have been popularized by the spread of electric lighting and our modern industrial workday.

While monophasic sleep is normal for the majority of the population, some people naturally tend to have biphasic and even polyphasic sleep patterns.

Biphasic vs. Polyphasic Sleep: What’s the Difference?

The terms “segmented” or “divided” sleep can also describe polyphasic sleep. Biphasic sleep defines a sleep pattern with two distinct phases. Polyphasic, on the other hand, is a pattern with more than two sleep phases that can be spread throughout the day.

While people are often naturally inclined to follow a biphasic or polyphasic sleep schedule, in some cases, polyphasic sleep can also be the result of a sleep disorder.

Irregular sleep-wake syndrome is one example of polyphasic sleep that stems for a sleep disorder. As the name suggests, people who have this condition tend to fall asleep and wake up at irregular intervals. The result is that they generally have troubles feeling well-rested and awake.

What Are Some Examples of Biphasic Sleep?

People can have a biphasic sleep schedule in a number of ways. Taking short naps during the day, as is common in Spain or Greece, evenly splitting your sleeping periods between day and night, or any variation of these, can all be types of a biphasic sleep pattern. The two most common types are the following

  • Taking a short nap. In this pattern, people typically sleep around six hours during the night and take a 2-minute nap in the middle of the day.
  • Taking a long nap. In this variation, people get around five hours of sleep each night and take longer naps of around one to one-and-a-half hours during the day.

A man takes a nap on the couchNumerous articles and posts in online forums talk of people who are successfully using biphasic sleep schedules to lead a more effective life. They say that reducing the hours they spend sleeping at night and taking short or long naps in the middle of the day helps them feel more alert and get more things done.

What Does Science Say About Biphasic Sleep?

While lots of people report having made positive experiences with splitting their sleep times, hard scientific data on the benefits of biphasic sleep and whether it does have health benefits is mixed at best. A 2016 article on Segmented Sleep in Preindustrial Societies reveals that before the industrial revolution and the emergence of electric lighting, people worldwide showed a clear preference for segmented sleep patterns.

According to the article, changes in the way we work in modern times, as well as advances in synthetic light technology, pushed most cultures toward the 8-hour monophasic sleep schedules that most people adhere to today. Before the industrial revolution, however, biphasic and even polyphasic sleep patterns were fairly common.

Moreover, an extensive 2010 evaluation of human sleep and cognition outlines the advantages of quick naps and their cultural prevalence. Short naps of around 5 to 15 minutes were found to be helpful and connected with better cognitive function. The same was found for naps of more than thirty minutes. The evaluation did point out, however, that more research at a much deeper level was required to reach a clear conclusion.

Other studies (one in 2012, one in 2014) reveal that napping (especially in more youthful kids) might not be the best solution for sleep quality or cognitive advancement, particularly if it impacts nighttime sleeping.

In grownups, even a quick 20-minute nap can be related to or increase the risk of bad sleep patterns or even sleep deprivation. Regular sleep deprivation has been shown to increase the likelihood of weight problems, heart disease, cognitive problems, and type 2 diabetes.

Is Biphasic Sleep Healthy?

As previously mentioned, there are mixed views on whether segmented sleeping is healthy or even safe. Not a lot of research has been done on the entire matter, so unless you have a good reason to switch up your sleep pattern, you may want to avoid it altogether, says Clete Kushida, MD, PhD, the medical director of the Stanford Sleep Medicine Center.

“There are so many unknowns,” he says. “[Is it] safe in the long term? How does it vary from individual to individual? How does age factor in, or medical conditions, or sleep disorders?”

If biphasic sleep patterns are what your body is naturally drawn to, there is no cause for concern. If you feel otherwise healthy, happy, and fulfilled, and you naturally sleep this way, you needn’t worry.

If you decide to give segmented sleeping a try, keep one thing in mind. Artificial light in the middle of the night could have an impact on your circadian rhythms – the internal clock that controls processes in your body. So keep light dim at night, and if you can, stay away from light that looks blue. Most modern computer screens and mobile phones have a special ‘night mode’ that filters out blue light, resulting in a slight orange tint on the screen.


Biphasic sleep schedules offer an alternative to the normal monophasic schedule. Lots of people do report that segmented sleep truly works for them.

Research has also shown that there might be advantages to biphasic sleep patterns.  They might help you get more done in a day without jeopardizing restfulness. For some, it might even enhance wakefulness, awareness, and cognitive function.

But, sleep science is far from having a final verdict in this matter. If anything, research has shown that while biphasic sleep may have benefits for some, others will actually develop a variety of health risks when adopting such a sleep pattern.

Watch out for signs from your body that biphasic sleep is not working for you. Look out for these signs of trouble:

  • Difficulty to focus
  • No patience/short temper
  • Taking risks you usually wouldn’t take
  • Feeling overly sleepy
  • Falling asleep at the wrong time, such as at work, in class, or while driving

If this has intrigued you, give biphasic sleep a shot, but not without consulting your doctor first. If you don’t experience benefits such as feeling more rested and wakeful, listen to your body and stick to the common monophasic sleep schedule that works for most people.

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