Sleep -- A Natural State

Sleep is supposed to be a natural state wherein the body takes rest for sometime everyday. Did you know that the fishes sleep with their eyes open? Well I cant do that but I can sleep anywhere at anytime with no rationale. I was travelling from the place where I work, to my home town in a bus yesterday and I slept off in the last crucial minutes, exactly when it was time for me to get down. I was so deep in sleep that I missed my stop and I got up 3 stops further. Blessing it should be that I got an alternate transport and reached back home safely. But what striked the most is the capacity for the mind to sleep off even when it knows that in the next few minutes there is an urgent situation to react . It seems the sleep timing is controlled by the circadian clock, by homeostasis and, in humans, by willed behavior. Was it by my own willing that I slept off ??? I dont remember that and so I did a little brwosing on this aspect and here's what I found about SLEEP....'the ZZZZZZZ's..............

Satge I sleep which is the drowsy period gives way to light or Stage II sleep, which is characterized by further decrease in the frequency of the ElectroEncephalogram (EEG) waves and an increase in their amplitude, together with intermittent high-frequency spike clusters called sleep spindles. Sleep spindles are periodic bursts of activity that generally last 1 or 2 seconds and arise as a result of interactions between thalamic and cortical neurons. In stage III sleep, which represents moderate to deep sleep, the number of spindles decreases, whereas the amplitude of low-frequency waves increases still more. In the deepest level of sleep, stage IV sleep, the predominant EEG activity consists of low frequency (1–4 Hz), high-amplitude fluctuations called delta waves, the characteristic slow waves for which this phase of sleep is named. The entire sequence from drowsiness to deep stage IV sleep usually takes about an hour.These four sleep stages are called non-rapid eye movement (non-REM) sleep, and its most prominent feature is the slow-wave (stage IV) sleep. It is most difficult to awaken people from slow-wave sleep and hence considered to be the deepest stage of sleep. Then there is a reverse to reach quite a different state called rapid eye movement, or REM sleep. In REM sleep, the EEG recordings are remarkably similar to that of the awake state.

In short the typical 8 hours of sleep experienced each night actually comprise several cycles that alternate between non-REM and REM sleep, the brain being quite active during much of this supposedly dormant, restful time!!!!!