The Nuance

The Case for the Nightcap

Why the occasional drink before bed may help your sleep

The Nightcap By Ferdinand Gotz, 1899. Image: Universal History Archive/Getty

Every week, the Nuance will go beyond the basics, offering a deep and researched look at the latest science and expert insights on a buzzed-about health topic.

At least since Shakespeare’s day, people have recognized that alcohol has curious and often contradictory effects on sleep. One character in Macbeth remarks that while alcohol can promote sleep, too much of it leads to restless nights. Ask a sleep scientist today whether booze helps or harms sleep, and you’ll get a similar reply. “What alcohol gives, it takes away,” says Timothy Roehrs, director of research in the Sleep Disorders and Research Center at Detroit’s Henry Ford Health System.

Roehrs has been studying alcohol’s effects on sleep since the 1980s and says drinking has a “paradoxical effect” on slumber. While there’s no doubt heavy drinking is a recipe for tossing and turning, there’s a case to be made that judicious amounts of alcohol can both promote and bolster sleep.

For people who drink sparingly, a little alcohol before bed can promote restful sleep at least in the short term. “After you consume alcohol, it actually enhances sleep,” says Roehrs. “So you fall asleep faster, and for at least three to five hours, your sleep might be deeper.”

A 2016 study from the University of Missouri found that alcohol may promote sleep by increasing the buildup of adenosine — a brain chemical that accumulates throughout the day as the body burns energy. Alcohol is such a potent sleep inducer that it’s actually included in some popular sleep medications. Some varieties of Vicks ZzzQuil, for example, contain 10% alcohol by volume.

“There’s a case to be made that judicious amounts of alcohol can both promote and bolster sleep.”

Not only does alcohol make us sleepy, it also changes the architecture of our sleep. While these changes to sleep rhythms are measurable proof that alcohol affects sleep, Roehr’s says these shifts, when subtle, aren’t always indicative of a poor night’s rest.