How Alcohol Screws with Your Sleep

Holiday cocktails and wine can have an unwanted side effect: messing with your zzz's. Here's what happens when you hit the pillow tipsy


It's weird: You fell asleep fast, woke up at your usual time, but for some reason you don't feel so hot. It's not a hangover; you didn't have that much to drink. But you brain feels foggy. What's the deal?

Depending on how much you drank, alcohol can mess with your slumber, says Joshua Gowin, Ph.D., a psychopharmacologist and alcohol researcher with the National Institutes of Health (NIH).

A quick chemistry lesson: When you take a sip of booze, it finds its way into your bloodstream and brain within 15 minutes, Gowin explains. (This is Your Brain on: Alcohol.) And once it hits your brain, alcohol triggers "a cascade" of chemical changes, he says.

The first of those changes are spikes in norepinephrine, which boost feelings of elation, excitement, and general alertness, Gowin says. Put simply, alcohol makes you feel good, which is probably why you decided to have a drink in the first place.

But once you quit or slow your drinking, that sense of elation starts to burn off. It's replaced by relaxation and fatigue, and sometimes confusion or depression, Gowin says. Also, your core temperature starts to drop-something that naturally happens when your body transitions into sleep, according to a review study from the NIH. Basically, you feel ready for bed, and it's probably easier for you to fall asleep quickly. (Can't sleep? 6 Weird Reasons You're Still Awake.) Lots of research, including one recent study from the University of Michigan, shows that alcohol effectively speeds your decent into slumber.

As for when you're actually snoozing? During normal slumber, your brain slowly descends into deeper and deeper "stages" of sleep as the night progresses. But a 2013 study from the U.K. found that alcohol propels your brain into the deepest sleep stages almost as soon as your head hits the pillow. That may seem like a good thing. But midway through the night, your brain downshifts into lighter stages of rapid eye movement (REM) sleep, the NIH research shows. At the same time, your body finally clears the alcohol from your bloodstream, which may have a disrupting effect on your zzz's, Gowin says.

For all these reasons, you're more likely to wake up during the night, toss and turn, and generally sleep poorly in the early morning hours after drinking. Even more: Alcohol seems to especially disrupt a woman's sleep, the U of M research shows. Bummer.

But it's important to note: Nearly all of these sleep-disrupting effects happen only if you drink enough to raise your blood alcohol content (BAC) above .05 percent. For most people, that's the equivalent of roughly two or three drinks, the NIH research states.

If you're a one-glass-of-wine kind of girl, you probably don't have much to worry about. In fact, most research suggests a drink or two may help you fall asleep without causing any of those early morning sleep disruptions. Just keep in mind: Gowin and other sleep researchers define a drink as 5 ounces of wine, 1.5 ounces of hard liquor, or 12 ounces of a beer like Budweiser or Coors, which has an alcohol-by-volume (ABV) content of five percent.

If you're heavy-handed when pouring cocktails or wine, or you tend to order pints of craft beers that have ABVs in the seven to eight percent range, your sleep may suffer even after a single drink. So now you know-and holiday parties, here we come!

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