What Is Biphasic Sleep?

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If you’re in the habit of taking a nap during the day and sleeping normally at night, your sleeping pattern is known as biphasic sleep. This sleep habit involves two sleep segments in a 24-hour window. Here’s what else to understand about biphasic sleep and whether it might be beneficial.

What is Biphasic Sleep?

Biphasic sleep describes a pattern in which someone divides their sleep time into two sessions in a single 24-hour window. These sleep sessions might both occur during the night or include a nighttime session and a daytime nap. Biphasic sleep differs from monophasic sleep, which is a pattern consisting of a single extended session of sleep during a 24-hour period.

How Does Biphasic Sleep Work?

Biphasic sleep is most commonly practiced in one of two ways. One method involves both night and day sessions, while the other consists of two sleep sessions at night. People who take daytime naps or siestas, which are common in some European cultures, may sleep for six hours or so at night and sleep again for 20 to 90 minutes during the day. Sleep duration during these two sessions generally comes down to personal preference.

Biphasic sleepers who get all of the sleep during the night may sleep for a few hours early in the evening, and then wake up for several hours during the night. They’ll return to sleep for a few more hours. Both sessions will amount to six to eight hours of sleep.

There’s no right or wrong way to practice biphasic sleep, and finding the right balance often comes down to trial and error.

Types of Sleep Schedules


Monophasic sleep is a sleep pattern in which you sleep once in a 24-hour period. Most Americans are monophasic sleepers, and the majority get their rest overnight.


People who split their sleep into two segments in a 24-hour period are biphasic sleepers. For example, children who take a midday nap and then sleep through the night are practicing biphasic sleep. 


Polyphasic sleep describes multiple sleep sessions in a 24-hour timeframe. Polyphasic sleepers may sleep for only a few hours at night and then take both a morning and afternoon nap during the day.

Is Biphasic Sleep Safe?

There isn’t much research into biphasic sleep. Still, existing evidence suggests that it’s generally considered harmless. That’s assuming you’re still getting between seven and nine hours of sleep in a 24-hour timeframe. If moving to biphasic sleep means you’re getting less sleep overall, that could lead to negative long-term effects. Keep in mind that it’s also normal to experience short-term sleep disruptions, such as feeling tired or grumpy, any time you’re shifting to a new sleep schedule.

Simple logistics can make biphasic sleep difficult to maintain. Parents with small children or those with full daytime work schedules may find that trying to sleep twice in 24 hours is not possible.

Can Biphasic Sleep Be Beneficial?

While more research is needed, there may be some benefits to biphasic sleep. 

  • Improved cognitive function. An older study from 2010 linked midday naps with improved cognitive function. Both short and long naps had benefits: Short naps were associated with reduced sleepiness and immediate cognitive improvements, while longer naps (more than 30 minutes) improved cognitive function for a longer length of time. Feeling sharper and more alert may also improve productivity.
  • Helps manage insomnia. People who struggle with insomnia symptoms may find it beneficial to get up and occupy themselves for a few hours before going back to bed. Understanding that biphasic sleep was a characteristic of our ancestors may also help people feel less anxiety over their own insomnia symptoms.
  • May improve dream recall. Waking up right after you’ve been dreaming may make it easier to remember your dreams, which could offer useful insights into your subconscious mind.

How to Choose the Right Sleep Schedule for You

There are historical indications that biphasic sleep schedules were a natural sleep pattern for humans at one point, and some people today may still find it complements their lifestyle and health. If that’s something you’d like to explore, try adding a brief nap in the early afternoon and see how you feel. 

Choosing our own sleep schedule often isn’t a choice at all, but a product of responsibilities like school and work. In that case, remember that the goal should be getting between seven and nine hours of sleep in a 24-hour period. If nighttime rest and a daytime nap are feasible, it may be worth trying. Remember that sleep patterns are very personal, and experimenting with different sleep schedules is the best way to find one that works for you and your lifestyle.

If you’re struggling to sleep well, it’s best to speak with your doctor for recommendations.

Frequently Asked Questions

Is it okay to sleep for 4 hours twice a day? 

While the general recommendation for sufficient sleep is seven to nine hours, there is evidence that biphasic sleep patterns are largely harmless. The key is ensuring that you’re getting seven to nine hours in a 24-hour period.

What is an example of a biphasic sleep schedule? 

If you sleep during nighttime hours in addition to a daily nap, you’re practicing biphasic sleep. Any sleep schedule in which you sleep in two segments during a 24-hour timeframe is considered biphasic sleep.

What is monophasic sleep vs biphasic sleep?

Most people are monophasic sleepers, meaning they get the majority of their rest at one time in a 24-hour period, usually through the night. Biphasic sleep means sleeping twice in a 24-hour period.

The Takeaway

Biphasic sleep is a technical way to describe two sleep sessions in a single 24-hour timeframe. There is evidence to suggest that people in ancient cultures practiced this sleep pattern, and it remains common in many parts of the world, including modern-day Spain and Greece. While biphasic sleep isn’t for everyone, you might find that an afternoon nap really does make you feel more alert and productive. Whether you adopt this practice or not, it’s a good reminder that good sleep comes in many shapes and forms.

[Editor’s Note: The information provided should not be considered a substitute for professional advice. Please consult a sleep doctor or other medical expert if you have questions related to your own health.]

Jessica Timmons