I'd love to see more research on this. I may occasionally consume, but one obvious effect is that I remember far less dreams if under the effect prior to sleeping that night. For me this is appreciated because dreaming is a source of mental annoyance the next day.

I have heard that it may reduce REM sleep. Consequently, many people who consume regularly then take a break will agree that after stopping they are flooded with more dreams than normal. They may be more intense, realistic, etc. But the effect subsides to normal quickly. Withdrawal is minor to non-existent for such people. Interesting!!

It also affects your appetite. Calories and cognition are very closely related.