Jan. 22, 2013 —
Science Daily/Alcoholism: Clinical & Experimental Research
Sleep is supported by natural cycles of activity in the brain and consists of two basic states: rapid eye movement (REM) sleep and non-rapid eye movement (NREM) sleep. Typically, people begin the sleep cycle with NREM sleep followed by a very short period of REM sleep, then continue with more NREM sleep and more REM sleep, this 90 minute cycle continuing through the night. A review of all known scientific studies on the impact of drinking on nocturnal sleep has clarified that alcohol shortens the time it takes to fall asleep, increases deep sleep, and reduces REM sleep.

"This review has for the first time consolidated all the available literature on the immediate effects of alcohol on the sleep of healthy individuals," said Irshaad Ebrahim, medical director at The London Sleep Centre as well as corresponding author for the study.

The onset of the first REM sleep period is significantly delayed at all doses and appears to be the most recognizable effect of alcohol on REM sleep, followed by a reduction in total night REM sleep.

"One consequence of a delayed onset of the first REM sleep would be less restful sleep," said Idzikowski. "The first REM episode is often delayed in stressful environments. There is also a linkage with depression."
http://www.sciencedaily.com/releases/2013/01/130122162236.htm