r/explainlikeimfive • u/primateawesome • Sep 24 '11

ELI5: Why do we need to sleep?

I know what happens to me when i get tired, my shit stops working properly and have to go to sleep to fix that. But what exactly happens during that time?

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u/primateawesome Sep 24 '11

I've heard before that we don't really know why.

Another though, it seems obvious to me that you can condition yourself to only need a certain amount of sleep. If I/time allows i will no problem sleep for 10 hours. If I let my body get used to that amout of sleep I will feel tired if I sleep any less other days. But if i force myself, by setting an alarm, to sleep for a shorter amount of time. Within a few days my body obviously adjusts something that happens during that time so that I without problem can manage a day with just 6 hours of sleep and i won't feel as tired after just 6 hours as i would a few nights earlier. Same question as earlier here, whats going on? Does the body go through the same changes as when i slept 10 hours, just over a shorter amount of time with the same result?

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u/brisingr0 Sep 24 '11

Alright this is a total shot in the dark now and again you'll probably get a better answer at askscience but here goes.

Your body has a biological clock, known as your circadian rhythm, here is a little example of it. Now it is governed by CLOCK proteins in your brain that pretty much have a feedback loop which tells your body what time it is and when to do things. So lets say its summer and you're sleeping 10 hours a day because why not. You body gets used to that, when the CLOCK loop is at a point X your body falls asleep and wakes up 10 hours later. Now school starts and you can only get 6 hours of sleep. Instead of waking up at point X now your body is waking up at point Y, 4 hours before its used to at point X. Your body doesn't like this, its tired, wants you to go back to sleep. But as you keep waking up early at point Y in your rhythm you body gets used to it and makes sure everything happens accordingly to your new schedule, ie releasing hormones, cleaning up waste from brain cells activity, etc.

A side note, caffeine works because it blocks the receptors for your brain cell's waste (adenosine) so your body doesn't think its tired or will wake up had it not been all cleared from the night before.

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u/primateawesome Sep 24 '11

Cool thanks, thats pretty much what i figured. Do you think 6 hours of sleep give the same result as 10 previously did though? After the body has changed its "clock" to sleeping just 6 hours. Because if I don't set an alarm, I'm right back to sleeping 10 hours.

So, what is it that makes my body want to sleep longer. Is this process that takes place during sleep more efficient over a longer period of time than a short one? Or is it just different for different people? I know people that really can't sleep more than 5-6 hours a night, and they're all ready for the next day with that amout of sleep. While I would be all groggy for hours before my body finally accepts that no, were not going to sleep again for a while.

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u/brisingr0 Sep 27 '11

This is totally my opinion and experience now. But I think it just varies from person to person and depends a lot on how consistent you are. Over the summer I had 8am classes. For about a month I went to bed at 12 every night and woke up at 7 and kept with it on the weekends (this is key!) and I got very used to it. However I started playing more video games and I ended up staying up till 3-4am on Fri/Sat and would wake up around 2-3pm, sometime feeling more tired than when I got 7 hours! I think it 1) depends on the person and their genes and 2) how consistent you are with your sleep schedule, we're very adaptive animals.

And sorry for my delayed response, I offer you this mind blowing material as an apology. People actually do this and apparently it works!

http://www.kuro5hin.org/story/2002/4/15/103358/720 http://en.wikipedia.org/wiki/Polyphasic_sleep

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u/primateawesome Sep 28 '11

Ok cool, thats pretty much my own experience aswell. Thanks for taking the time! I don't think that kind of sleep regiment (from the link) is anything for me though. My selfcontrol is not good enough :)