Quote Originally Posted by Az.
it knocks you out but it disrupts your REM period of sleep, in almost the same way alcohol does....which results in you not getting the rest you need.
I believe this to be true from my own experience. When abstaining after a number of consecutive THC days, I notice a significant increase of intense dreaming... and feel more rested the next morning.

I imagine that the body of a long-term/lifetime daily smoker must somehow adjust to the lack of REM sleep. Maybe this effect wears off after very long-term use, or maybe they stay awake throughout the high and go to sleep sober (naaaaah).