TL;DR:
Biphasic sleep involves dividing your rest into two distinct segments — a pattern with deep historical roots that’s now gaining renewed interest for its potential cognitive benefits. Historically, this pattern was the norm before the industrial revolution[1]. Recent studies suggest it may support better memory, mood, and alertness, especially for those with irregular or disrupted sleep cycles [2];[3]. 

Curious if it could work for you? Muse S helps you monitor sleep architecture and brain activity so you can track how different rhythms impact your recovery and focus.

If you've ever found yourself waking up in the middle of the night  alert, calm, and oddly clear-headed, you're not alone. In fact, your brain might be tapping into a natural rhythm that humans followed for centuries. This pattern is called biphasic sleep, and it's gaining renewed interest from researchers and wellness communities for its potential cognitive and emotional benefits.

From improved memory to more manageable sleep routines, biphasic sleep may offer a sustainable alternative to the traditional 8-hour block [4]. In this article, we’ll explore what biphasic sleep is, its historical roots, potential advantages, and how you can safely test it — especially if you’re already tracking your brain health with Muse for clinical grade sleep and brain health tracking. 

What are Biphasic Sleep patterns?

Biphasic sleep refers to a sleep pattern divided into two distinct periods throughout the day. Rather than getting the recommended 7–9 hours of sleep in one continuous block, biphasic sleep breaks this into two segments [2].

This could look like a 1–3 hour “first sleep” beginning around 9 p.m., followed by a period of wakefulness, and then another 5–8 hours of rest — a pattern observed in pre-industrial societies [1]. Alternatively, some people follow a more modern version: a 1–2 hour midday nap combined with 6–8 hours of sleep at night [5].

Biphasic sleep is also called segmented, divided, or bimodal sleep, and is gaining traction among those exploring more personalized or flexible approaches to rest.

Biphasic vs. Monophasic Sleep

Monophasic sleep refers to the pattern most common in Western societies — a single, uninterrupted sleep period lasting 7–9 hours. While this schedule aligns with modern work and school demands, it may not be the most biologically natural or beneficial sleep rhythm [1].

Biphasic vs. Polyphasic Sleep

Polyphasic sleep involves three or more sleep periods per 24 hours. Some examples include the Uberman Schedule (20-minute naps every four hours) and the Everyman Schedule (three short naps during the day paired with a 3-hour core sleep at night).

Although advocates claim improved focus and productivity, the evidence doesn’t support these claims. Research has found that polyphasic sleep can lead to chronic sleep deprivation, especially when total sleep time falls below the recommended 7–9 hours per day [6].

Even when total sleep duration is sufficient, polyphasic patterns may still disrupt natural circadian rhythms. One study found that students following a polyphasic schedule experienced lower academic performance and circadian misalignment equivalent to flying across 2–3 time zones  [7].

Why Biphasic Sleep Is making a comeback

Modern life is pushing more people to explore sleep alternatives that better match their biological rhythms and daily demands. Shift workers, parents, entrepreneurs, creatives, and those with delayed sleep phase disorder often find that conventional monophasic sleep doesn’t always align with their needs. For them, biphasic sleep can offer greater flexibility while still meeting total sleep needs.

The rise of remote work, flexible schedules, and biohacking culture has also accelerated interest in segmented or bimodal sleep. Wellness communities and digital health platforms are increasingly embracing personalized sleep optimization, with a focus on tracking brain activity, deep sleep tracking, and energy patterns rather than sticking rigidly to the 8-hour rule [8];[9].

Advances in wearable tech such as EEG headbands and sleep trackers make it easier than ever to understand how different sleep patterns affect your mood, focus, and recovery. Devices like Muse have benefits, giving you real-time insights into your brain activity and sleep cycles, so you can experiment and find the rhythm that works best for you.  For more on how this kind of tech supports sleep awareness, check out the benefits of sleep trackers.

The forgotten history of Biphasic Sleep

Unless you live in countries like Spain or Greece where midday naps are still culturally supported — the idea of sleeping in anything other than one 7–9 hour block might seem unusual. But thanks to the research of historian Roger Ekirch, PhD, we now know that monophasic sleep only became the norm during the Industrial Revolution [1].

Prior to the 18th century, sleeping in two segments was far more common across many cultures. In his extensive review of historical documents, Ekirch uncovered hundreds of references to a “first sleep” and a “second sleep,” particularly in pre-industrial Europe.

Some researchers believe that this wakeful window may have also contributed to more vivid dreams, given its proximity to REM cycles and the calm, low-stimulus environment of the night. Learn more about the science of dreams blog, where we explore what happens in the brain during these dream-rich phases.

The “first sleep” typically occurred between 9 p.m. and 11 p.m., followed by a natural period of wakefulness. During this time, people often engaged in routine activities, from tending livestock to reading or praying. Then, around 1 a.m., they would return to bed for their “second sleep” until dawn [1].

So what changed? The rise of artificial lighting and factory-based work schedules compressed daily routines, forcing sleep into a single continuous block. In many ways, our current sleep norms are an adaptation to electric lighting and industrial timekeeping, not necessarily to our biology [10]

 

Biphasic Sleep today

As we mentioned earlier, most cultures today follow a monophasic sleep pattern, but that hasn’t always been the case. In fact, segmented sleep still occurs naturally in some parts of the world.

In a 2015 field study, David Samson, Director of the Sleep and Human Evolution Laboratory at the University of Toronto, explored sleep patterns in the remote community of Manadena in northeastern Madagascar. This region, located at the edge of a national park and without access to electricity, experiences nighttime conditions similar to those of early human history [11].

The researchers used actimeters, or wrist-worn movement trackers, to monitor participants’ sleep cycles. After a week, they found that most individuals naturally awoke for a period of activity between midnight and 1:30 a.m., then returned to sleep until sunrise. This pattern closely mirrors the biphasic sleep rhythm described in historical records [11].

These findings suggest that the shift to monophasic sleep may have been driven more by the introduction of artificial light than by biological necessity.

That said, many cultures still embrace a form of biphasic rest through afternoon naps. Siesta culture is alive and well in countries like Spain, Greece, and Italy, where midday rest remains a structured part of daily life.

 

Should You Try a Biphasic Sleep Schedule?

The research on biphasic sleep schedules comes in a few different forms.

Short naps of 20–30 minutes have been linked to benefits like improved alertness, cognitive performance, and stress resilience. Learn more in our breakdown of the science behind power napping and work productivity [12];[13];[14].

Longer naps of 60–90 minutes allow you to move through a full sleep cycle, which may provide added benefits associated with deep sleep. Studies show that 60–90 minute naps can improve learning, short-term memory, attention, and emotional regulation, while also supporting better stress tolerance [15]; [16].

The only catch with longer naps is sleep inertia — that grogginess when you first wake up. But with the right wind-down and recovery routine, the benefits often outweigh the sluggish start. Here's how to get ready for bed the right way.

When it comes to biphasic sleep patterns rooted in our evolution, research supports the idea that this could be our brain’s natural rhythm. In one small but notable study, researchers limited participants’ access to artificial light to just 10 hours a day, mimicking pre-industrial conditions. After four weeks, participants had naturally shifted to a biphasic sleep cycle, experiencing a natural period of wakefulness between two nighttime sleep blocks [17]. 

When it comes to biphasic sleep patterns rooted in our evolution, research supports the idea that this could be our brain’s natural rhythm. Explore how our understanding of sleep stages evolved in the history of sleep.

Ultimately, whether or not you should adopt a biphasic sleep schedule depends on your needs. If it helps you get more and better sleep, it could be worth a try.

Common Biphasic Sleep Schedules to Try Out

The most important thing is that- no matter the schedule, you still want to get 7-9 hours of sleep every 24-hour period!

The Mid-Day Catnap — Sleep for 6-7 hours at night plus a 20 or 30 minute power nap during the day.

Siesta Sleep Schedule — 5-6 hours of sleep at night and a 1-2 hour long nap in the afternoon.

Traditional “First” and “Second” Sleep — This pattern will likely mean you have to go to sleep earlier than usual. Sleep for 1-3 hours, wake up for 1-2 hours, then head back to sleep for another 6-8 hours.

If you’re struggling with getting a good night’s sleep, know that you’re not alone, and there are options.

Learn more about how Muse’s Digital Sleeping Pill could help you fall asleep more easily and sleep soundly through the night.

Explore how Muse supports better sleep →

FAQ: Biphasic Sleep, Answered

Is biphasic sleep healthy?

For some people, yes. Research suggests that biphasic sleep can support memory, stress regulation, and overall rest quality — especially when total sleep time remains within the recommended 7–9 hours. That said, it’s not ideal for everyone, especially if it leads to insufficient or irregular sleep.

What’s the difference between biphasic and monophasic sleep?

Monophasic sleep is one uninterrupted sleep block per night (typically 7–9 hours). Biphasic sleep divides rest into two periods, such as a long nighttime sleep and a daytime nap, or a segmented first and second sleep overnight.

Is biphasic sleep natural?

Yes — for much of human history, it was the norm. Historical records and studies suggest that segmented sleep patterns emerged naturally before the invention of electric light and industrial work schedules.

Can biphasic sleep improve cognitive performance?

Some studies have linked biphasic patterns and strategic napping to improved focus, memory consolidation, and stress resilience. However, benefits depend on individual needs and total sleep quality.

How do I try a biphasic sleep schedule?

Start by experimenting with a consistent wake-sleep-wake-sleep pattern or by adding a 60–90 minute midday nap. Track how you feel and consider using a tool like Muse to monitor brain activity and sleep stages for personalized feedback.

 

Sources:

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Sleep we have lost: Pre-industrial slumber in the British Isles. American Historical Review, 106(2), 343–386. https://doi.org/10.2307/2651611

[2] Muench, A., et al. (2016).
The impact of sleep timing and segmented sleep on cognitive performance and alertness. Sleep and Biological Rhythms, 14(3), 197–204. https://doi.org/10.1007/s41105-016-0040-6

[3] Frontiers in Psychology (2014).
The benefits of short bouts of solitude and quiet rest. https://www.frontiersin.org/articles/10.3389/fpsyg.2014.00585/full

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[11] Samson, D. R., Crittenden, A. N., Mabulla, I. A., Mabulla, A. Z., & Nunn, C. L. (2017). Hadza sleep biology: Evidence for flexible sleep–wake patterns in hunter–gatherers. American Journal of Physical Anthropology, 162(3), 573–582. https://doi.org/10.1002/ajpa.23160

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[15] Lahl, O., Wispel, C., Willigens, B., & Pietrowsky, R. (2008). An ultra short episode of sleep is sufficient to promote declarative memory performance. Journal of Sleep Research, 17(1), 3–10. https://doi.org/10.1111/j.1365-2869.2008.00622.x

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