Does drinking alcohol before bed improve your sleep?

Short answer

No. Drinking a lot does help you fall asleep faster, but from about two drinks, dream sleep (REM sleep) shrinks, sleep breaks up later in the night, and the body's recovery markers during sleep fall in step with how much you drank.

Does drinking alcohol before bed improve your sleep?
'Alcohol → fall asleep fast → sleep well' — does this formula hold?
People often say a drink before bed is good for sleep because you nod off quickly. We checked studies that measured brain waves and heart rate on nights after drinking to see if falling asleep fast means sleeping well.
Do you fall asleep faster?
Only after drinking a lot
An analysis that pooled 27 studies found that the time to fall asleep got shorter only after about 5 standard drinks or more, about 60 g of alcohol or more for a 70 kg (154 lb) person. Drinking less did not shorten the time to fall asleep.
But what about dream sleep?
It shrank from about 2 drinks
In the same analysis, just about 2 standard drinks, about 35 g of alcohol or less for a 70 kg person, made dream sleep (REM sleep) start later and run shorter. The more people drank, the more it shrank.
Across the whole night?
Deeper early on, more waking later
A review of studies found alcohol deepens sleep in the first half of the night but causes more waking in the second half. In a study of 30 people who drank before bed 3 nights in a row, total deep sleep did not change and REM sleep dropped every night.
Did the body rest during sleep?
Recovery markers dropped even with a drink or two
In heart rate data from 4,098 people in daily life, recovery during the first 3 hours of sleep fell by 9.3 percentage points after low drinking, 24.0 after moderate and 39.2 after heavy drinking. Low meant 17.5 g of alcohol or less for a 70 kg person. People who exercise were affected the same way.
What about training days?
Muscle recovery slowed too
When 8 people drank about 12 drinks after exercise, the rate of building muscle protein was 24% lower even with protein, and 37% lower without it. When 11 people drank alcohol equal to about 70 g for a 70 kg person after leg exercise, strength loss 36 hours later grew from 12-28% to 34-40%.
Bottom line: alcohol does not improve sleep
Falling asleep fast is not the same as sleeping well
Alcohol only sped up falling asleep at around 5 drinks, and well before that, from 2 drinks, REM sleep shrank and sleep broke up later in the night. The body's recovery markers also fell in step with the amount. If sleep is the goal, leaving out the alcohol works better.