Why do we sleep?

Originally posted by Andrew Hamilton
yes -but why do we get tired (as in sleepy tired and not physically tired) ?
The usual evolutionary explanation that I have heard is to save energy at night when we cannot do much useful work but I believe the amount of energy actually saved has been calculated to not be much (at least compared to resting without sleeping) and while we are asleep we ...[text shortened]... re venerable to attack from predators and other dangers (at least our ancestors must have been).

It would have been cold at night on the plains... Maybe sleeping is like a micro-hibernation. We wouldn't have been able to do much anyway as we've evolved to cope with daytime conditions and have poor eyesight in the dark. Maybe conserving that little bit of energy was worth it in evolutionary terms.

I wonder if, with a larger amount of stimuli nowadays, whether we need more sleep now than we used to, to process the information.

Originally posted by Feastboy
It would have been cold at night on the plains... Maybe sleeping is like a micro-hibernation. We wouldn't have been able to do much anyway as we've evolved to cope with daytime conditions and have poor eyesight in the dark. Maybe conserving that little bit of energy was worth it in evolutionary terms.

I wonder if, with a larger amount of stimuli nowadays, whether we need more sleep now than we used to, to process the information.

I wonder what people in the Northern regions do in the summer when they have 20 hours of daylight? Do they sleep less because it is warmer and there is more sunlight?

Do we need more sleep when there is less sunlight, in the winter?

Originally posted by dannyUchiha
I read somewhere (sorry,I forgot where!!!) some time ago, about a study in that field that said that the hours between 9:00 PM and 12:00 midnight are the most critical ones for the brain's "rejuvenation"process. It basically said that during these 3 hour, your brain secreted an enzyme that speeds up this process by double. That means that if you sleep we ...[text shortened]... your 8 hoursjust like everybody else.

I hope this helps on your war against morpheus.

The idea that a specific time for sleep is flawed. Think of a hospital nurse, who always works the night shift. According to the body 9PM to you is 9AM to her etc.

I can sometimes get 12 hours straight sleep, and often sleep more than 8 hours. I believe sleep is practiced, that is if a person sleeps for 6 hours a day for most of their life that is the amount they need to sleep to feel rejuvenated whereas someone who sleeps 9 hours a day for most of their life that is how much they need.

Originally posted by Feastboy
I usually have five or six hours sleep a night. It varies quite alot from person to person... My girlfriend needs at least 8 and a half hours or she's grumpy as hell. I tend to need less.

Sleeps important to rest your brain and also for the learning process. As far as I'm aware sleeping lets your brain store information you've learned through the day, ...[text shortened]... ves. I'm not sure if it just seems shorter though.... They have been asleep for more of it!

See number 8:

http://www.realage.com/StayingYoung/Articles.aspx?aid=10503

Great site.

I sleep about 4 hours a night unless I am being diligent about taking my multi-vitamins. Total trade off. When sleeping more, I am definitely more productive and efficient throughout the day. When up late, I have expanded time for things like email, forums and with my family (I have teenagers who seem to naturally tend to be up late at night).