Biphasic Sleep

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When we think about going to bed and getting “tucked in for the night,” we usually have in our minds the idea that we will sleep for one long period before waking up.

This single chunk of nightly sleep, known as monophasic sleep, is the standard in modern society. But historical research has discovered that this way of sleeping hasn’t always been the norm.

Instead, in many societies, people tended to break their sleep into two segments with an extended period of wakefulness between them. This is known as biphasic sleep.

With a significant number of people struggling with insomnia and other sleeping problems, biphasic sleep has seen an upswell of interest. Many people also wonder if biphasic sleep can improve their productivity or their physical health.

This guide goes in-depth to explain the key information about biphasic sleep. It explains what biphasic sleep is, reviews its history, and gives examples of biphasic sleep schedules. It addresses the potential benefits and downsides of biphasic sleep to help determine if this type of sleep schedule could be a good fit for you.

older man asleep

What is Biphasic Sleep?

At its most basic level, the word biphasic refers to something that is done in two stages or phases. Biphasic sleep, then, is when a person’s total daily sleep is composed of two segments. This is in contrast to monophasic sleep, which is when all of a person’s sleeping is done in one large chunk.

What Are Examples of a Biphasic Sleep Schedule?

There are multiple different ways to follow a biphasic sleep schedule, but there are two examples that are most well-known: two nightly sleeps and siesta sleep.

Two Nightly Sleeps

In this example of biphasic sleep, a person normally goes to bed within a few hours of dusk. This “first sleep” lasts for three to four hours, and then they wake up for a period of 30 minutes to two hours. At that point, they have a “second sleep” for another three to four hours.

To illustrate this example, a nightly sleep schedule with two sleeps could look something like this:

  • 8:30 p.m.: begin first sleep
  • 12:30 a.m.: wake up / mild activity
  • 2:30 a.m.: begin second sleep
  • 6:30 a.m.: wake up

In this example, the person’s total sleep time is eight hours, but it is divided into two segments.

During the time between the first and second sleep, a person doesn’t just lie in bed tossing and turning. Instead, they are awake and deliberately doing some type of activity. In most cases, this activity would be mild and not excessively stimulating in a way that could make it more difficult to begin the second sleep.

Siesta Sleep

The word “siesta” is Spanish for nap, and it most often refers to a period in the afternoon that is designated for a short rest. In the siesta sleep style for biphasic sleep, a longer chunk of sleep, normally from six-and-a-half to seven hours, happens at night, and it is supplemented by a nap in the afternoon.

An example of a siesta sleep schedule could look like the following:

  • 11:30 p.m.: begin first sleep
  • 6:00 a.m.: wake up
  • 1:30 p.m.: nap
  • 3:00 p.m.: wake up from nap

In this example, the person’s total sleep time is eight hours, but it is broken into one longer and one shorter segment with a sizable interval between them.

Are There Other Schedules For Biphasic Sleep?

The two examples of biphasic sleep schedules mentioned here are not the only ways that someone can sleep biphasically. Any schedule in which a person’s total sleep time is divided into two parts is considered biphasic.

The Two Nightly Sleeps and Siesta Sleep approaches are more common, but keep in mind that the times listed above are just meant to serve as examples. Any individual could adjust those times forward or backward depending on their own preferences or needs.

What is the Best Schedule for Biphasic Sleep?

There is no single best schedule for biphasic sleep. What works best for one person may not work for someone else, and the daily demands of family, social life, work, and school can complicate a person’s ability to strictly follow some types of biphasic sleep schedules.

An important thing to note from both of the schedules shown above, though, is that the person’s total sleep time equals eight hours. This is the recommended amount of sleep for adults; children and adolescents need even more nightly sleep. Regardless of the schedule, a biphasic sleep schedule should not be used as a way to try to reduce total sleep time.


What is the History of Biphasic Sleep?

While monophasic sleep is the standard in modern society, there is evidence that this has not always been the case. Historical research has found numerous references and examples to a biphasic sleep pattern.

Because sleep tracking and record-keeping was so different before the development of electricity and other modern devices, there is no clear-cut way to know how the majority of people slept. However, there are indications that biphasic sleep was common.

A. Roger Ekirch, Ph.D. and Professor of History at Virginia Tech University, has been at the forefront of investigations into how sleep may have been different in the past. He cites hundreds of examples from written works that describe a first and second sleep with an active waking period between them. These examples do not appear to be mentioned in isolation but seem to reflect a common societal practice.

Based on historical research, the waking period in segmented sleep was employed for all types of activity that varied based on the particular society. It could involve things like adding wood to stoke the fire in the stove during winter, having a snack or beverage, reading, writing, and even sex.

Dr. Ekirch and other researchers have argued that the 17th century witnessed a transition away from this long-held approach to segmented sleep. They believe that the development of street lighting made it easier for people to stay awake longer into the evening. As people were awake longer, it effectively eliminated the active period between first and second sleep. This process combined with other social changes related to the development of industrial society to make monophasic sleep the norm.

It should be noted that not everyone accepts this hypothesis that biphasic sleep was the historical norm. Some researchers have argued that it was limited primarily to Northern Europe and was not common in tropical societies.

Debate continues about pre-industrial sleep habits in different parts of the world, and we may never be able to know exactly how our predecessors slept. Nevertheless, the research by historians like Dr. Ekirch has demonstrated that the concept of sleep that we have today is not a given and that segmented sleep schedules can be found in historical records.

What Does the History of Biphasic Sleep Mean for Sleep in Modern Society?

What the history of biphasic sleep means for us today is a controversial question.

For many researchers like Dr. Ekirch, the shift away from biphasic sleep may explain why certain sleep problems, such as insomnia, have intensified in the modern age. They argue that it may be related to other health problems like stress, depression, and anxiety as well.

At the same time, it is important to recognize that the biphasic sleep cycle described in history took place in a markedly different time. It is difficult to draw lessons about optimal lifestyle habits from pre-industrial societies that had no electricity and thus no artificial light, no air-conditioning, no modern medical facilities, and certainly no mobile phones. Even if we wanted to follow the same nightly schedule as biphasic sleepers in history, we would undoubtedly be doing so in a dramatically different social and economic context.

Because of these profound differences and the gaps in the historical record, it is hard to know what conclusions can be drawn from the history of biphasic sleeping. Is there a more “natural” way for us to sleep? Or is our best sleep schedule always determined based on our environment? More research may cast more light on the history of sleep, but the answers to these questions are likely to remain subject to extensive disagreement and debate.


What Are the Potential Benefits and Risks of Biphasic Sleep?

As historical knowledge of biphasic sleep has increased, many people have become intrigued by the potential benefits of employing this sleep schedule. Interest is especially piqued when people learn that it is believed that great thinkers like Leonardo da Vinci and Benjamin Franklin slept in this way.

Unfortunately, there is little concrete research that demonstrates the benefits and risks of biphasic sleep. While there are many claims that can be found for its pros and cons, there is a lack of hard data from rigorous studies to support most of those claims.

As a result, there is no firm recommendation about whether you should try biphasic sleep. Instead, in this section, we’ll address some of the potential benefits and risks to try to help you decide whether it could be a good choice for you.

Does a Biphasic Sleep Schedule Improve Sleep?

We do not have enough detailed research to say whether biphasic sleep helps or harms sleep quality for people in general. While there are ways that it may help sleep, there are also significant concerns that it can reduce total sleep time and sleep quality.

Some advocates for biphasic sleep believe that it improves the overall quality of sleep and generally focus on a few key arguments:

  • It’s a natural way to sleep: referencing pre-industrial history, proponents of biphasic sleep contend that it is a more natural sleep pattern.
  • It may address sleep maintenance insomnia: some people have sleep maintenance insomnia, which means they wake up in the middle of the night and can’t get back to sleep. The goal of a biphasic cycle is to accommodate this by having an intentional period of wakefulness during the night.
  • It may reduce sleep anxiety: many people suffer from anxiety that comes from worrying about trying to sleep through the night. This anxiety can make it harder for them to get to bed initially, and it can keep them from getting back to sleep if they awaken during the night. By normalizing segmented sleep, some people find that biphasic sleep reduces these anxieties.

There are also ways that a biphasic schedule can harm the quality and quantity of your sleep:

  • It may decrease total sleep time: for some people, it may be hard to fall asleep and wake up according to a biphasic cycle. In this case, a person may spend more time lying awake in bed, reducing their total sleep time.
  • It may cause irregular sleep: some people who follow a biphasic sleep schedule, especially with afternoon naps, have considerable irregularity in their daily sleep times. They may adjust the timing and length of their sleep periods a great deal from day-to-day to make it fit within their schedule. Unfortunately, research has found that irregular sleep times can have negative effects on thinking and productivity even if a person still gets the recommended amount of daily sleep.
  • It can contribute to fragmented sleep: in many studies, fragmented sleep has been found to have negative consequences, including reducing productivity and creativity.
  • It can disrupt the circadian rhythm: our body’s internal clock, also known as a circadian rhythm, works in response to our daily light exposure. Segmented sleep, especially if it is irregular, may contribute to misalignment of our circadian rhythm with the day-night cycle, creating potential sleep disruptions including circadian rhythm sleep-wake disorders.

There is no hard scientific evidence that indicates that one way of sleeping is more natural or more desirable than the other. What works best is different for every individual.

For many people, especially people accustomed to monophasic sleep, trying to adopt a biphasic sleep schedule can lead to significant sleeping problems. For other people, especially those who struggle with monophasic sleep, a biphasic approach may feel like a more comfortable and natural schedule.

Does Biphasic Sleep Improve Productivity?

Sleep quality has a critical impact on our overall productivity, so whether biphasic sleep makes us more or less productive depends in large part on how it influences sleep.

Research studies in college students found that academic performance was strongly correlated with having a regular sleeping schedule. Students with greater variance in their sleep and wake times had reduced cognitive function and productivity. In this way, a biphasic sleep schedule could pose problems to productivity primarily if it creates day-to-day irregularity in sleep times.

For some people, biphasic sleep may feel more productive because they can accomplish tasks during the waking time at night that happens between the first and second sleeps. However, if this waking time comes at the expense of total sleep, it can drag down cognitive function and overall productivity. Furthermore, while some people find a midnight working session to be useful, others may find that they are more productive in the morning or at night before bed.

A siesta-style biphasic sleep schedule may help some people improve productivity by giving them a boost of energy after an afternoon nap. It is known that most people experience a lull in energy in the mid-afternoon and that a nap can help counteract that dip. At the same time, properly timing that nap is important and can be difficult. If someone naps for too little, too long, or according to an irregular schedule, it may have a counterproductive effect on attention and energy.

Does Biphasic Sleep Improve Athletic Performance?

Some athletes try to “hack sleep” in order to improve athletic performance. This has led some people to argue in favor of biphasic sleep for bodybuilding or other athletic competitions.

It is important for athletes to get enough sleep and to have restful, restorative sleep, but there is no sound evidence that biphasic sleep improves athletic performance compared to monophasic sleep. The sleep schedule that best promotes sleep quality in any individual is most likely to positively contribute to their athletic pursuits.

It should be noted that many high-level athletes use short cat naps, often of around 15-20 minutes, before competitions to try to get a small extra boost of energy. But this type of very short nap is distinct from the sleep segments involved in a typical biphasic sleep schedule.

Is a Biphasic Sleep Schedule Practical?

Even for people who are intrigued by biphasic sleep, following a biphasic sleep schedule can be a major challenge in modern society.

Having a long waking period in the middle of the night typically requires going to bed early, and this may be difficult for many people as a result of their social life or work obligations. In addition, being awake in the night may be hard for people who share a bed or living space and are at risk of disturbing a sleeping partner.

For a siesta-based biphasic approach, work or school schedules may make it impractical to find a consistent time for a daily nap. This can force someone either to reduce their nap length or to take their naps irregularly, either of which may reduce sleep quality.

In general, the organization of modern society is much more permissive for monophasic than biphasic sleep. That said, not everyone operates according to the same schedule or has the same daily obligations, so it may be much more practical for some individuals to follow a biphasic sleep plan than others.

Are There Other Risks From Biphasic Sleep?

Because research about biphasic sleep is limited, there may be risks that are not fully understood. One example is that some experts caution that a biphasic sleep schedule may pose greater dangers for people who have or may be prone to developing depression and other mood disorders. These disorders have connections with circadian rhythms, and disruption of the circadian rhythm may heighten the risk of depression and its symptoms.

Please remember that while our guide is thorough and well-researched, it is not a replacement for medical advice. Always consult your doctor or qualified physician with any questions or concerns you have regarding medical conditions, treatments, and advice.


How Do I Know if Biphasic Sleep Works For Me?

As the prior sections demonstrate, there’s no easy way to know if biphasic sleep is right for you. For people who currently sleep with a monophasic schedule and are considering a change, it may be helpful to consider the following questions:

  • Are you sleeping well now? If you are sleeping well and don’t suffer from insomnia or daytime sleepiness, making a change may pose a greater risk than benefit. If you have sleeping problems, especially with sleep maintenance insomnia, there may be more potential upside to trying a different sleep schedule.
  • Can you improve your monophasic sleep? Before trying a radical change in your sleep schedule, you can consider whether there are other steps that you can take to improve your monophasic sleep. Talking to your doctor about any sleep issues can help reveal if you have any underlying conditions that are harming your sleep. In addition, taking simple steps to improve your sleep hygiene can go a long way to helping you get the sleep you need.
  • Would a biphasic sleep schedule feel more natural to you? For some people, biphasic sleep just seems to make sense. This is often the case for people who find that they naturally wake up in the night or are strongly drawn to an afternoon siesta. For other people, the biphasic cycle runs counter to their natural tendencies. Be honest with yourself and consider whether biphasic sleep really seems natural in your case.
  • Is it logistically practical for you to shift to biphasic sleep? Think about the daily obligations for your family, work, school, and social life. Given those demands, is it reasonable for you to be able to implement two sleeps at night or a daily siesta? Keep in mind that you want to try to standardize your sleep and wake times as much as possible.
  • Are you able to do a trial run of biphasic sleep? Deciding to try biphasic sleep doesn’t have to be a “once-and-for-all” decision. If you are curious about trying this method, think about whether there’s a good time for you to do a test run for a week or two to see how practical and effective it is for you. If you do a test run, consider using a sleep journal or tracker so that you can analyze how much sleep you’re actually getting and how you feel during the day.

Deciding whether to try biphasic sleep isn’t a simple decision. For most people who aren’t actively having problems with monophasic sleep, there’s no strong research to indicate that you should make a change. But if you are struggling with sleep and haven’t found other approaches to be helpful, a biphasic cycle can be an option to consider.

How Do You Get Started With Biphasic Sleep?

If, after considering all the potential benefits and downsides, you’ve decided to give biphasic sleep a try, you might be wondering how to get started.

The first thing to decide is which type of biphasic sleep schedule you want to use. Whether it’s two nightly sleeps or a siesta-style approach, it can be useful to sketch out what you think would be your ideal biphasic sleep timing. Some smartphone apps can even help in designing and implementing a plan for biphasic sleep.

Don’t be surprised if it takes time to adjust to a new sleep schedule. In many cases, it can be helpful to gradually change your sleep times to help your body get accustomed to the difference. Whatever schedule you try, remember that you want to try to follow it closely and with discipline in order to build consistency to your routine.

Documenting your sleep with a sleep diary or with a sleep tracker can give you some feedback about how well you are sleeping now and how well you sleep after making a change. This kind of data can also help to make adjustments as you experiment with biphasic sleep.


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