You know, maybe someone can do an experiment.  Keeping dosage, smoking method, size and hold of hits constant, maybe someone can try it during these times:

1) first thing upon waking

2) right before bed

3) setting the alarm to go off during the first light sleep stage

4) during REM sleep

5) during heavy sleep

and post the subjective results from your test. If we can get enough results maybe we can get closer to getting some answers to how our brains work (with and without DMT).

Also, the diet/medications taken during this time must also remain rather constant.