I'm okay with staying up late at night to accomplish tasks that need to be done for reasons, and just in general, I enjoy staying up late. The overall darkness of the atmosphere gives a kind of calmness and pleasure, but that's just because I'm on a weird sleeping schedule. But, since that goes into morning, and into the afternoon, I end up accidentaly pulling an all nighter. Is REM quality and length affected by sleep deprivation? Also, does caffeine interfere with REM?