The concept and practice of a nightcap—having a small alcoholic drink before bed in order to get a good night’s sleep—has been around since the 1700s. But recently, its validity as a sleep aid has been questioned.

A new review of published studies, involving the sleeping habits of over 500 people who had a nightcap before a snooze in the sleep lab, reveals that a quick drink before bed won’t actually help you get a better night’s sleep. Those who drank, no matter the amount, did in fact fall asleep faster and spent more time in a deep sleep for the first half of the night. However, as the night progressed, they woke up more frequently, experiencing increased sleep disruption—presumably as the alcohol’s effects wore off. . .