『I don't understand rem sleep very much』

If you think so,please look at this graf.

This is the sleep log of my one day. We use this day because it is the plainest.We used "good sleep cycle",the application of iPhone. Please refer to this.

The remarkable point is the time when we reach deep sleep,stage4,at first. First deep spleep is followed by socond deep sleep in about 90 minutes;human deep sleep appears by a 90 minutes' period.

Oops,this is rem sleep explanation,isn't it? I'll explane rem sleep all at once.