What is The Polyphasic Cold Adaptation?

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Most of us stick to a pretty typical sleep schedule: we go to bed at night and wake up in the morning, spending somewhere between seven and nine hours asleep. But there’s a small subset of people who have turned to polyphasic sleep in an attempt to increase their productivity by reducing their time in bed (or because they work atypical hours).

Polyphasic sleep is a sleep schedule that involves multiple periods of rest throughout the day, as opposed to the traditional monophasic sleep schedule where you snooze for one long period at night. To lull the body into sleep, many proponents of this method attempt to alter their thermoregulation.

Thermoregulation is the body’s ability to maintain a stable internal temperature, which coincides with our natural sleep-wake cycle (also called our circadian rhythm). While we’re fast asleep, our body temperature slowly decreases. As we get closer to waking up, it increases.

Polyphasic sleepers claim they can take advantage of leveraging external temperatures to help them sleep, which is where cold adaptation comes in.

What is Polyphasic Cold Adaptation?

Polyphasic cold adaptation is the deliberate exposure to cooler temperatures with the intention of altering the body’s natural sleep cycle. Research shows that when you fall asleep, your core body temperature drops. The cooler your body gets, the more likely you will reach for that blanket or cuddle up under the covers.

Polyphasic cold adaptation, then, is the practice of using colder temperatures to signal the body that it’s time to sleep. It’s thought that by exposing the body to colder temperatures, you can help train it to fall asleep more easily, especially during your daytime naps when your body naturally runs hotter.

Exercise and Polyphasic Cold Adaptation

Exercise can also help to regulate body temperature and, as a result, may improve sleep quality. When we exercise, our muscles generate heat, and our body temperature rises, promoting wakefulness.

Getting your sweat on as soon as you wake up from your core sleep (depending on which type of polyphasic sleep schedule you’re following) can help to increase your body temperature, making it easier to stay awake during the day. It also might help increase wakefulness at night when you start to get chilly.

Nutrition and Cold Adaptation

Perhaps one of the biggest switches polyphasic sleepers have to make is getting used to eating in the middle of the night. Most of us are used to eating our meals during the day and fasting overnight. But when you’re sleeping in cycles throughout the day and night, your body will need fuel at all hours.

It’s important to eat nutrient-dense foods that will help you stay awake in-between sleeps, but it’s also important to make sure you’re not overloading your system with food that will make you sluggish.

Protein is a particularly important nutrient for polyphasic sleepers as it increases your cortisol, increasing your energy.

Benefits of Polyphasic Cold Adaptation

While the research has not yet verified the anecdotal claims many polyphasic sleepers make, here are the most common potential benefits:

  • You may experience more REM sleep. REM, or Rapid Eye Movement, sleep is the deepest and most restorative stage of sleep. Polyphasic sleepers claim that cold adaptation increases REM sleep because they can fall asleep more quickly and deeply.
  • You may find it easier to fall asleep. While polyphasic sleepers have been touting the benefits of cold adaptation for years, there is some evidence that cooling the brain (by exposing the forehead area to cooler temperatures) may help those with insomnia fall asleep as fast as those without insomnia.
  • You may improve your sleep quality. Sleeping in cooler rooms may improve sleep quality, since heat exposure can increase wakefulness. So if you’re looking to improve your sleep, cold adaptation may be one method to help you achieve that goal.

Downsides of Polyphasic Cold Adaptation

Exposing yourself to moderate levels of cooler temperatures for short periods of time shouldn’t have any drawbacks, though you should talk with your doctor about any changes to your sleep. Polyphasic sleep in general, however, may not be without its potential drawbacks. The most common complaints are:

  • Sleep deprivation: Anything less than seven hours of sleep is considered sleep deprivation, and polyphasic sleep schedules often have people sleeping for less than that. Chronic sleep deprivation can cause anxiety, high blood pressure, depression, and even psychosis.
  • Poorer performance:  When you’re sleep deprived, your mental and physical performance suffers. Studies have shown that students who follow polyphasic sleep patterns perform worse on tests than those who follow monophasic sleep patterns.

Tips for Cold Adaptation in Polyphasic Sleep 

If you’re interested in trying cold adaptation to improve your polyphasic sleep, there are a few things you can try to make the transition easier.

Start gradually

Don’t go from sleeping in a warm room to sleeping in a freezing cold room overnight. Start by turning the temperature down a few degrees each night until you’re comfortable sleeping in cooler temperatures. Make sure not to take the thermostat to very cold temperatures that could be unsafe.

Eat protein as soon as you wake up

Eating protein as soon as you wake up can help to increase your energy and wakefulness. A small snack of some nuts, Greek yogurt, or cheese when you get up from a sleeping period might do the trick.


Getting some activity based on your abilities and health can also help to increase your energy and wakefulness. If you’re able, a quick walk around the block or a short burst of cardio can help to get your blood flowing and keep you awake in between sleep.


Sleeping is essential. But how we sleep is constantly evolving. Those engaging in polyphasic sleep—which involves sleeping in shorter cycles throughout the day and night—have turned to cold adaptation to help improve their quality of rest.

While the research has not yet verified the anecdotal claims many polyphasic sleepers make, there are potential benefits to be had from cold adaptation, including more REM sleep, easier falling asleep, and improved sleep quality.

However, it’s important to start gradually and be aware of the potential drawbacks before making any major changes to your sleep schedule.

Source List

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Hanson J, et al. (2022). Sleep Deprivation. https://www.ncbi.nlm.nih.gov/books/NBK547676/

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