Why do we need to sleep?
338793
To get more energy. If you don't you will get in Sleep debt. Also your brain, reflexes, and body would not do as good. When you are in sleep debt you have to sleep more to get back on track. Also the recommended hours of sleep are 8 to 9 hours.\n\nFor kids they need 10 to 11 hours of sleep.\nAlso Dr. Know (from TV) did tests on a lab rat (Not a rat but a human) by forcing them to only get 4 hours of sleep each night and did a test a found out their reflexes were slowing, their memory test wasn't as good, and when they recovered (pay their sleep debt) they did better.
490073
sleep  more  at   night.
1164333
Its because your muscles have been overelaxed.  Sleep is to completly shutdown muscle systems so they can rebuild (muscles have minor tears that occur all the time).  \n\nAnd you are more than likely hungry/have to go to the bathroom.
751429
This depends on each person. I only want/need eight hours. Mrs. Thatcher (and others) famously needed only four hours. I knew a girl who regularly had twenty-two hours. None of these people thought they were getting "too much" sleep. They simply slept the amount they felt they needed.\nWithout medication and assuming good health, I would think the body naturally wakes when it has had sufficient sleep.
295982
The body needs what the body needs. If you fell to sleep you obviously needed the rest. It may take you a day or two to get back on schedule but you will be fine.
64411
when we sleep our brains dont shut down but slow down.  we rejuvinate our brain causing us to think more clearly and be more preductive in just about everything we do.  It can effect the body in the long run.  Our muscles dont get the proper rest they require.  here are two links.  the first goes into great detail about what it does to the brain and the second is sleep deprivation fron diccovery.com
479213
get some regular sleep!
308667
Sleep is VERY important.  100 years ago, people got 8-9 hours of sleep, today it's dropped to 6-7 hours.\n\nThe body heals itself when you sleep, also helps the brain to rest.  Did you know that if you go for 2 days without sleep that you can have all the effects and hallucinations of being on drugs?  You react slower in driving, simple tasks become overwhelming, etc.\n\nMake sure you get enough sleep, the body needs it!\n\n(When you become a parent, you never get enough sleep) so get it while you can
629002
Your body is telling you it wants more sleep...listen to it.
1547
According to sleep researchers, sleep does not have to be uninterrupted in order to fulfill the body's sleep requirements. Your body and mind are getting rest. Just pretend that you are not frustrated as you are, and be happy that your body and mind are being adequately rested despite this.
532132
Our cells do not sleep.  The function of cognizance shifts from the real world to the dream world.  Yes, as we expand our knowledge our capacity to learn increases.  It is a false notion that there is only so much "space" in the brain\nWe all function far below or mental capacities.
554901
Your body is trying to tell you that it needs a rest or it just needs food into your system because it is not getting enough oxygen to the brain. The best thing to do is to take a nap but, if you don't have time get something good to eat or something cold to drink.
1087263
we need to have our eyelids closed while we sleep to proctect our eyes from drying out. so those who might not look completely closed must at least close their eyes some times. or they've had eyelid surgery which has injured their protective mechanism. in which case they'd have to use drops or ointments to protect their eyes while they sleep.
1121117
sleeping is still one big unsolved mystery.. till now there is no clear definition on why does the body needs sleeping or what happens in the brain during sleeping hours .. actually all living creatures do need sleeping each their own way. We spend half of our life sleeping.. really strange !! As for your question.. closing your eyes, opening your hand, lifting your leg are all body acts that can't be compared to sleeping.
244672
read before you sleep, and read in dim light. this actually makes u sleep faster because the brain becomes more tired.
17294
What I've read, there is some confusion about the function of sleep.\n\nOne aspect is to properly rest your muscles, the other may be to reconsolidate thoughts from that day. At certain times during sleep (REM phase) the brain is very active, so it is unlikely that you can call this rest.\n\nFrom A-Level Psychology I remember that brains can adapt to sleeping habbits so it is possible to reduce the amount of sleep you get. To go without sleep completely for long periods is generally considered unhealthy.
133078
if you are normally active you need 5-7 hour total sleep during a 24 hour period. limit your naps to 20 minutes or you will feel sleepy the rest of your day or night. if you are not active you could probably stay in bed all day and night. get some fresh air and some sunlight