Why do we need to sleep?

[tehno]

Why do we need to sleep at all?
I have even heard of people that never sleep,and of people that need to sleep a very short period a day (say ~1 hour).
Some mammals (cats,dogs) are also going through so called REM phase of a sleep.
I'm not sure but watching him ,I think my little parrot also experience a REM phase.
What do you think:Is sleeping just a resting or there is more to it?
Lucid dreams are quite an interesting phenomenon.

I found neat page about sleeping:

http://www.sleepfoundation.org/

 

[jim mcnamara]

One answer:

Humans have poor night vision compared with our day vision. At night we are sitting ducks for predators with good night vision. Inactivity in a safe place during dark periods is a very adaptive strategy to avoid becoming lion chow.

The reason people in industrialized (especially urban) areas tend to have altered sleep habits relates to electric lighting. People in rural areas without electrification tend to have more old-fashioned sleep habits. Fewer distractions, I guess.

The one hour-per-night thing: Seems possible for a VERY short time, but eventually and without several naps during the day, the person would likely develop severe sleep deprivation symptoms. Unless it's because the person is taking methamphetamines (or similar drugs).

The simplest explanation is that somebody is exaggerating his/her ability to stay awake. A less simple explanation: There are medical conditions, some related to brain trauma or altered brain chemistry, that cause dramatically altered sleep periods.

Read about primary insomnia -
http://www.emedicinehealth.com/primary_insomnia/article_em.htm