Asked by: Steven Druskovich, by email
Many people use alcohol to help them sleep. During the first part of the night it increases non-REM sleep (including deep sleep) and suppresses REM sleep (when most dreams occur).
But as the blood alcohol level drops, the reverse happens: sleep is shallower and waking more frequent, which means more dream recall, and more REM sleep, leading to vivid dreams and nightmares. This poor sleep can then make you tired and want to repeat the drinking the next night.