Having a few drinks may help you fall asleep, but that deep slumber continues for only part of the night. After that point, getting shut-eye becomes more difficult, according to a new review.
Researchers analyzed information from 20 previously published studies that looked at the effects of alcohol on sleep. Together, the studies included more than 500 people who drank low, moderate or high amounts of alcohol before going to bed, and underwent testing while they snoozed in a sleep lab.
Regardless of how much people drank, alcohol reduced the time it took them to fall asleep. In addition, drinking alcohol, no matter the quantity, increased deep sleep during the first half of the night.
However, sleep disruption, or waking after falling asleep, increased during the second half of the night, the researchers found.
In addition, moderate doses (2 to 4 drinks) and high doses (more than 4 drinks) of alcohol reduced overall rapid eye movement (REM) sleep during the night. REM sleep is a stage of sleep during which dreams occur, and is thought to be important for memory.