The Unexpected Impact of Caffeine and Alcohol on Sleep

For 42 days, the study followed 17 finance traders in New York City, a group known for consuming large amounts of caffeine and alcohol. Each morning of the study, participants took an online survey with questions about their prior day’s caffeine and alcohol use and their previous night’s sleep.

Caffeine and alcohol consumed on the same day appeared to offset each substance’s expected negative impact on sleep. Lead researcher Frank Song called these results “intriguing,” as the researchers didn’t expect them.  

Since caffeine consumption tends to shorten sleep and alcohol tends to result in poor sleep quality, the researchers expected that combining the two would make sleep worse than either on its own. Instead, they found that alcohol consumption may counteract the reduced sleep time usually caused by caffeine. And caffeine may help a person feel more awake after a night of reduced sleep quality caused by alcohol.

This isn’t to say that using caffeine to wake up in the morning and alcohol to fall asleep at night is a healthy choice. While it may help in the short term, the researchers refer to this practice as “self-medication” and caution against using it as a long-term strategy. 

Self-medicating in this way may lead to a cycle in which a person needs more caffeine each morning in order to feel alert after poor sleep, then needs more alcohol each evening to balance the day’s caffeine. All the while, a person’s sleep deteriorates due to the effects of both substances, and this poor sleep can harm their overall health.