After reading this, I know that sleeping is an universal function, and that basically everything with a brain has the need to sleep.

However, I am still confused to what extent it is necessary to sleep at night to regain energy, or if some rest during the day provides a sufficient energy-regain?


closed as unclear what you're asking by anongoodnurse, rg255, AliceD, March Ho, James Apr 18 '16 at 13:18

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  • 1
    $\begingroup$ The circadian clock is entrained to sleep-wake patterns. (Sun)Light has a strong capability of adjusting and resetting that clock. Hormonal balance and other functions in the body, in turn, are synced to it. Hence, your question will depend much on whether you are aksing what happens after acute reversal of the sleep/wake cycle, or whether you mean what happens when you revert it for prolonged periods of time. Also, what do you mean with 'some rest'? Of course powernaps during the day can help. I vote to close because it is unclear what you are after. $\endgroup$ – AliceD Apr 15 '16 at 9:25

I think the reason is primarily, that it is more quiet (the chance is very low that other people are disturbing your sleep) in the night as well as it is also dark. Keeping in mind, that the brain "gets tired" due to some proteins (melatonin) and in contrast, being more awake during the day, it seems to be just logical that the sleep in the night is healthier, thus providing more energy.

  • $\begingroup$ And isn't the production of melatonin controlable by outter conditions such as illumination and noiseness? Or do you think the biological clocks can keep going in the time undependent environment? $\endgroup$ – Probably Apr 15 '16 at 8:47
  • $\begingroup$ Of course, but it needs some time until it can rise high enough, sufficient for deep sleep at night, where your immune system can regenerate. Some people get health problems such as high blood pressure or weight gain when their sleep at night is insufficient. Found e.g. with shift workers. However, a "quick nap" (about 20 min) at daytime will provide you new energy, as you just rest quickly and don't get to relaxed, where your muscles feel weak, such as after a longer sleep. $\endgroup$ – TheGreenOne Apr 15 '16 at 8:52
  • $\begingroup$ i would like to know what happens exactly when you sleep? if you can answer me! (thanks by the way, your answer was a logical and brief one) $\endgroup$ – 0x0584 Apr 15 '16 at 13:08

A couple of quick google searches would tell you that the important part of sleep is the REM (Rapid Eye Movement) sleep.

REM stands for rapid eye movement. During REM sleep, your eyes move quickly in different directions. That doesn't happen during non-REM sleep. Usually, REM sleep happens 90 minutes after you fall asleep. The first period of REM typically lasts 10 minutes. Each of your later REM stages gets longer, and the final one may last up to an hour. Your heart rate and breathing quickens.You can have intense dreams during REM sleep, since your brain is more active.(1)

During an eight-hour sleep pattern, the average adult only spends approximately 1.5 hours (or 20% of total sleep time) in rapid eye movement (REM) sleep. REM sleep is important because it is the restorative part of our sleep cycle. Typically, you begin the sleep cycle with a period of non-REM sleep followed by a very short period of REM sleep. The period of non-REM sleep is made up of stages 1 to 4. Each stage can last from 5 to 15 minutes. A completed cycle of sleep consists of a progression from stages 1 to 4 before REM sleep is attained, then the cycle starts over again.

However, if your REM sleep is disrupted even one night, your body won’t follow its normal circadian sleep cycle (“inner clock”) progression. Instead, you will slip directly into REM sleep as a result of not getting the right amount of sleep the night before. You will also go through extended periods of REM sleep until you “catch up” on this stage of sleep. Poor sleep cycles can cause grogginess, a lack of concentration and more.(2)

During day, brain might not get enough time to restore itself as one can hardly sleep for 2-3 hours during day. Though your body might get refreshed after this, your brain might not. Also, as @TheGreenOne says, there are lot more chances of day sleep getting disturbed than night sleep. Another thing is that the brain is habitual to sleep at its normal time (night) (see SCN), so it won't be very easy to get in/out of the habit to sleep during day.


  1. http://www.webmd.com/sleep-disorders/guide/sleep-101
  2. https://www.azumio.com/blog/health/rem-sleep
  • $\begingroup$ there's some great information up there, thanks $\endgroup$ – 0x0584 Apr 15 '16 at 13:06

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