Sleep

Ever wondered why do we sleep?
Can we live without sleeping?
Does animals sleep?. How long?

Nowadays i am sleeping for a quite longer time. No work......... :-).
Anyway here is what i found about sleep (Source: Wikipedia-Sleep )....
Sleep more learn more!!

Theories regarding the function of sleep

1) Restorative theories of sleep describe sleep as a dynamic time of healing and growth for organisms. During sleep growth hormone levels increase, and changes in immune function occur.

2) One process known to be highly dependent on sleep is memory. REM sleep appears to help with the consolidation of spatial and procedural memory, while slow-wave sleep helps with the consolidation of declarative memories. When experimental subjects are given academic material to learn, especially if it involves organized, systematic thought, their retention is markedly increased after a night's sleep. Mere rote memorization is retained similarly well with or without an intervening period of sleep.

3)Another view is that the function of sleep is for memory processing. This theory argues that saving memory directly into the long-term memory is a slow and error prone process, and, thus, proposes that the memory formed during waking time is not saved directly into the long-term memory; instead it is saved into a temporary memory store first. The function of sleep is to process, encode and transfer the data from the temporary memory store to the long-term memory store.

(This is more easily understandable .... RAM/ROM process........Hahaa)

Animal Sleep

Animals vary widely in their amounts of sleep, from two hours a day for giraffes to 20 hours for bats. Generally, required sleeping time decreases as body size increases. Cats are one of the few animals that do not have most of their sleep consolidated into one session, preferring instead to spread their sleep fairly evenly throughout the day.

Water mammals "sleep" with alternate hemispheres of their brains asleep and the other awake. They need to do this so they can breathe above water while sleeping. Migratory birds also seem to sleep this way.

Even fish and fruit flies appear to have a "sleeplike" state. This alternation of the sleeplike state and its absence is referred to as a "Basic Rest and Activity Cycle", or BRAC. Since the modern definition of sleep is defined using EEG criteria, and such tiny brains preclude the recording of EEG's, this may not technically be described as sleep. However, if fruit flies are repeatedly disturbed so that they can not rest, they have what is referred to as a "rest rebound". This behavior is strikingly similar to that exhibited by mammals and birds in similar conditions.

Many animals hibernate in a deep sleeplike state during winter to conserve body heat and energy. Estivation is a similar state in which other animals hibernate to escape the heat of summer.

Cattle, horses, and sheep are unique in that they can sleep while standing, though for cattle and sheep, REM sleep will not occur in such a position. For REM sleep to take place, the animals must lie down. Sleeping while standing is thus only partial sleep. However, birds may have periods of REM sleep while perched. Some breeds of dogs usually sleep throughout the day like cats, while other breeds have only one daily sleep session. While dreaming, dogs sometimes make a quiet barking sound.