Art of Sleeping..

There are 4 phases of sleep...
Phase 1 is when we go from a completely wakeful situation to sleep, this transition phase lasts about half a minute to 7 minutes. In this phase we wake quickly and we would obstinately maintain that we had not gone to sleep.
Phase 2 is the first real sleep, in which there are still fragments of thoughts and where a sound of average volume will wake us up. The phase of light sleep, phase 2, is the first 'real' sleep phase and lasts about 10 to 20 minutes.
After a short time we sink deeper in phases 3 and 4, and then we are completely relaxed. We only wake up it there's a very loud noise. Phase 4 is the deepest sleep and if we are woken in this phase, we often don't know where we are.
Strangely enough, we don't stay in this deep sleep until morning. But we go back from phase 4 to phase 1.

Zhongwei..4:04am liao still cant sleep..zZ