Why does alcohol make you sleep so poorly?


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Anyone who’s gone out for a night of drinking knows what it’s like to fall deeply asleep upon returning home, only to spend the next few hours tossing and turning in bed. Among its many other side effects, alcohol has a varied effect on just how much and how well we sleep.

Alcohol has long been used as a home-remedy type of sleep aid — hence the term “nightcap,” referring to a drink consumed before bed. Regardless of how much alcohol is consumed, it reduces the amount of time it takes a person to fall asleep. Alcohol even has the ability to increase deep sleep — the kind that promotes bodily restoration — during the first half of the night.

But that’s where the so-called good side effects of booze before bed stop. Studies show that consuming any amount of alcohol delays the onset of rapid eye movement sleep, better known as the REM stage. During REM, the brain is most active and dreaming often occurs, making it an important part of a good night’s sleep. 

In addition to delaying the onset of REM, consuming moderate or heavy amounts of alcohol decreases the amount of overall REM sleep. REM, which helps restore the body, usually comprises about a quarter of a night’s sleep, and not achieving the desired amount can negatively affect memory, motor skills and concentration. 

Unfortunately for women, the effects of alcohol on sleep appear to be worse than for men. Women tend to have more disruptive sleep after drinking, which may be attributed to the fact that women metabolize alcohol more quickly, and therefore reach the tossing and turning stages sooner than their male counterparts.