Biphasic sleep is a sleep pattern. It may also be called bimodal, diphasic, segmented, or divided sleep.
Biphasic sleep refers to sleep habits that involve a person sleeping for two segments per day. Sleeping during nighttime hours and taking a midday nap, for example, is biphasic sleep.
Most people are monophasic sleepers by nature. Monophasic sleep patterns involve only one segment of sleep, usually during nighttime hours. It’s thought that the custom of sleeping for one 6- to 8-hour segment per day may have been shaped by the modern industrial workday.
Monophasic sleep is typical of most of the population. However, biphasic and even polyphasic sleep patterns are known to manifest naturally in some people.
Biphasic vs. polyphasic
The terms “segmented” or “divided” sleep can also refer to polyphasic sleep. Biphasic sleep describes a sleeping schedule with two segments. Polyphasic is a pattern with more than two sleeping periods throughout the day.
People might actively pursue a biphasic or polyphasic sleep lifestyle because they believe it makes them more productive. It creates more time for certain tasks and activities during the day, while maintaining the same benefits of monophasic sleeping at night. It may also come to them more naturally.
People may voluntarily or naturally follow biphasic or polyphasic sleep schedules. However, in some cases, polyphasic sleep is the result of a sleep disorder or disability.
Irregular sleep-wake syndrome is one example of polyphasic sleep. Those who have this condition tend to go to sleep and wake up at scattered and irregular intervals. They usually have difficulties feeling well-rested and awake.
How it’s done
A person can have a biphasic sleeping schedule in a couple of ways. Taking afternoon naps, or “siestas,” is a traditional way of describing biphasic sleep. These are cultural norms in certain parts of the world, such as Spain and Greece.
- Short nap. This involves sleeping around 6 hours each night, with a 20-minute nap in the middle of the day.
- Long nap. One sleeps around 5 hours each night, with about a 1 to 1.5-hour nap in the middle of the day.
In many articles and in online communities, some people report that biphasic sleep schedules really work for them. Taking naps and splitting their sleeping schedule over the day helps them feel more alert and get more done.
While many people report positive personal experiences with biphasic sleep, the research on whether there are true health benefits — or detriments — is mixed. On the one hand, a 2016 article on segmented sleep patterns shows global favor for the sleep pattern.
The article also posed that the rise of the modern work day, along with artificial illumination technology, herded most cultures in the developing world toward 8-hour monophasic sleep schedules at night. Before the industrial era, it’s argued that biphasic and even polyphasic patterns weren’t unusual.
To further support this, a 2010 review discussed the benefits of brief naps as well as their cultural prevalence. Short naps of around 5 to 15 minutes were reviewed as beneficial and associated with better cognitive function, as were naps of longer than 30 minutes. However, the review did note that more studies were needed at a deeper level.
Conversely, other studies (one in 2012, one in 2014) show that napping (particularly in younger children) may not be the best for rest quality or cognitive development, especially if it affects nighttime sleeping.
In adults, napping can be associated with or increase the risk of poor sleep patterns or sleep deprivation. If regular sleep deprivation occurs, this increases the probability of obesity, cardiovascular disease, cognitive difficulties, and type 2 diabetes.
Biphasic sleep schedules provide an alternative to the typical monophasic schedule. Many people report that segmented sleep really works wonders for them.
Science, along with a look at historical and ancestral sleeping patterns, shows that there could be benefits. It could help you get more done in a day without compromising restfulness. For some, it may even improve wakefulness, alertness, and cognitive function.
However, research is still lacking in this. Further, it is observed in studies thus far that all people are different, and biphasic schedules may not work for everyone.
If they interest you, give them a try with the approval of your physician. If they don’t improve feelings of restfulness and wakefulness, it’s smart to stick to the typical monophasic schedule that works for most people. It’s not worth the potential increased health risks due to lack of sleep and irregular sleep patterns.