Because sleep is so important for memory and learning (and gathering evidence suggests sleep problems may play a significant role in age-related cognitive impairment), I thought I’d make quick note of a recent review bringing together all research on the immediate effects of alcohol on the sleep of healthy individuals.
The review found that alcohol in any amount reduces the time it takes to fall asleep, while greater amounts produce increasing amounts of deep sleep in the first half of the night. However, sleep is more disrupted in the second half. While increased deep sleep is generally good, there are two down sides here: first, it’s paired with sleep disruption in the second half of the night; second, those predisposed to problems such as sleepwalking or sleep apnea may be more vulnerable to them. (A comment from the researchers that makes me wonder if the relationship between deep sleep and slow-wave activity is more complicated than I realized.)
Additionally, at high doses of alcohol, REM sleep is significantly reduced in the first half, and overall. This may impair attention, memory, and motor skills. Moreover, at all doses, the first REM period is significantly delayed, producing less restful sleep.
The researchers conclude that, while alcohol may give the illusion of improving sleep, it is not in fact doing so.
 . Alcohol and Sleep I: Effects on Normal Sleep. Alcoholism: Clinical and Experimental Research [Internet]. 2013 :n/a - n/a. Available from: http://onlinelibrary.wiley.com/doi/10.1111/acer.12006/abstract