clara. 2005 Dec 11. More on the issue of sleep.... <http://neurobiology.pharyngula.org/more_on_the_issue_of_sleep1/>. Accessed 2006 May 06.

Posted on Neurobiology on Sunday, December 11, 2005

More on the issue of sleep...

The subject of sleep really interests me and I wanted to read more so here is what I found...
The article was called The Science of Sleep and some of the facts in the article are similar to what we discussed during last weeks Neuro Slam, but there were some aspects I didn't know.
It is still unclear as to why we need sleep. Some researchers believe that sleep provides the body a chance to recuperate from the day, but in all actuality the amount of energy saved by sleeping 8 hours is only about 50 kCal...which is roughly the same amount of energy in a piece of toast. All that is known, is that sleep is essential to maintaining our cognitive abilities (memory, speech etc.) or important for development of the brain.
Experiencing a lack of sleep is a good way to feel and realize why we need sleep. After one night without sleep, concentration becomes more difficult, attention span shortens considerably, and memory is the first thing to fade. Also, research shows that sleep deprivation causes individuals to not be able to respond to changing situations. Judgement also lapses; sleep deprivation is thought to be a factor is such disasters as Chernobyl and the Challeneger shuttle explosion.
There are two types of sleep, non-REM (which has four stages) and REM. Here are the four stages of non-REM sleep:
Stage 1-(Light Sleep) In this stage we are half awake and half asleep and can easily be awakened.
Stage 2-(True Sleep) The longest stage. Within ten minutes of light sleep we enter this stage, and it lasts about 20 minutes. Breathing and heart rate slow down.
Stage 3&4-(Deep Sleep) Stage 3 the brain produces delta waves and breathing and heart rate are at their lowest. In Stage 4 there is limited muscle activity and rythmic breathing;this is the stage when children experience night terror.
REM sleep usually begins 70 to 90 after we fall asleep and we have 3 to 5 of these cycles per night. This is the period when dreams occur, our eyes move around and heart and breathing rate rise slightly.
As far as how much sleep we should get, it varies. Everybody is different, but the average is found to be aboue 7.75 hours.

Here is the link for the article: sleep and here is a link to a interesting sleep quiz: Quiz