[No registration!] Is polyphasic sleep dangerous?

An altered circadian rhythm

An Altered Circadian Rhythm

The purpose of this section is to show the health effects of polyphasic sleep altering the circadian rhythm, and whether this actually happens.


In a nutshell, the circadian rhythm is our body clock, and it’s shifted by external cues. At certain points during the day, specific hormones are released, the body temperature is altered and the ideal sleep peaks are determined. All this is based on the biological clock.  If you start messing with it, you could possibly develop some negative side effects.

Here, circadian health will be assessed from two different perspectives; first, what happens if you don’t maintain good circadian health. And second, what happens if your sleep schedule actually alters the architecture of your circadian rhythm.

Not ensuring a good health

If you disrupt your circadian rhythm by exposing yourself to bright light during the night, eating during the night, or exercising at irregular hours, you can constantly shift the timings in the circadian rhythm. This could lead to the development of cardiovascular diseases, obesity, diabetes, and so on.

Because of this, the polyphasic community has some recommendations in place to ensure that we avoid making the body think that it is daytime when it’s actually night. More information on that can be found here.

Sleep schedules altering the circadian rhythm

What happens if your sleep pattern alters the structure of your circadian rhythm?
Up to date, there is some evidence from how the timing of light alters the actual architecture of your circadian rhythm. For example, in the research article called “In short photoperiods, human sleep is biphasic“ by Thomas Wehr, the author found evidence for an altered internal structure of the circadian rhythm from shortening the length of the photoperiod.
That’s fine, but if it turned out that the circadian rhythm was altered from internal processes, like the sleep pattern of people, that could in turn result in several negative aspects coming forth as a result from it. External processes that alter the timing of the circadian rhythm are called zeitgebers, and thus far there have been found seven of them:

  • Light,
  • Temperature,
  • Exercising,
  • social interactions,
  • Eating,
  • Atmospheric conditions, and
  • Some medications.

So if sleep was on this list and you were on a Segmented schedule, your body could start thinking that it’s a new circadian day every night after you wake up from the first core, which would carry the same risks as prematurely exposing yourself to light during the night.

At this point in time, it is unknown if polyphasic sleep alters the structure of the circadian rhythm. However, there doesn’t seem to be any evidence for it. It seems more like sleep is a manifestation of the circadian rhythm rather than a contributor to setting the circadian timings. One good example to represent this idea is from a study called “Timing of REM sleep is coupled to the circadian rhythm of body temperature in man.” by Czeisler et al. It has a good visual on a desynchronization sleep pattern, and we can clearly see that the optimal rem timing isn’t shifted even though the subjects are sleeping at different times each day.














In fact, desynchronization studies would most likely not be possible to complete if sleep could alter the circadian architecture. Just something to consider here.


If you are looking for evidence to debunk polyphasic sleep, this could be another topic to pray upon. What you would need to find evidence for is:

  1. That altering your sleep structure impacted the circadian timings.
  2. That the altered circadian timings resulted in negative health aspects.

As of late, this is the point with the least weight against polyphasic sleep – if it turned out that this was the case, especially if the circadian morning was set at a strict time with several other zeitgebers. One way sleep appears to be able to affect the circadian rhythm today is by inhibiting other zeitgebers to be utilized at the time you’re sleeping. Basically if you are asleep, you can’t eat or exercise. But it’s still affecting us on a secondary level rather than a primary level.

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