What Actually Happens to Sleep After a Drink

Before this review, research on alcohol and sleep was scattered across small, inconsistent studies. This was the first attempt to bring all of it together into a single, coherent picture of what happens to normal sleep after drinking. Across dosages, alcohol consistently shortened the time it took participants to fall asleep and produced a more consolidated, deeper first half of the night, largely explaining why alcohol has long had a reputation as a sleep aid. But that same body of evidence showed the trade-off just as consistently: sleep became progressively more disrupted in the second half of the night, and this disruption reliably outweighed the earlier improvement as the dose increased.

As a narrative synthesis of decades of smaller trials rather than a single large study, its conclusions inherit the limitations of the underlying research, much of it conducted in young, healthy volunteers rather than the general population. Its lasting contribution is simply correcting the story: alcohol's sleep-inducing reputation and its sleep-disrupting reality are not contradictory findings, they are two halves of the same night.