If you want to get a restful night’s sleep, an alcoholic
nightcap isn’t the best way to go. In a new journal
article in Alcoholism: Clinical and
Experimental Research, scientists reviewed all known studies of how boozing
affects snoozing in healthy individuals.
Led by Dr. Irshaad Ebrahim, medical director of the London
Sleep Centre, the authors found that drinking alcohol can have a big impact on your
sleeping brain. And that, in turn, can affect how refreshed and alert you feel
the following day.
Here’s a glance at what happens inside your brain when you doze
off with alcohol in your system.
Alcohol is a sedative, so it makes falling asleep easier.
Dr. Ebrahim and his colleagues found that this holds true whether people drink
a little or a lot.
Slow-wave sleep—deep sleep associated with slow brain waves—is
crucial for overall health. The body repairs and regenerates tissue, builds
bone and muscle, and may strengthen the immune system during this sleep stage. Slow-wave
sleep is also necessary for feeling rested and energetic the next day.
Dr. Ebrahim and his team found that alcohol increases
slow-wave sleep during the first half of the night. That might sound like a good
thing. However, according to Dr. Ebrahim, deeper sleep may worsen sleep apnea and
sleepwalking in vulnerable individuals. Plus, any gains made during the first
half of the night may be offset by fitful sleep later.
First Half of the Night:
Rapid eye movement (REM) sleep—named for the way the eyes
dart around rapidly behind closed lids—is the type of sleep in which dreaming typically
occurs. REM sleep stimulates regions of the brain used to learn and form
memories. Scientists believe that the brain may use this time to sort and
selectively store new information acquired during waking hours.
Normally, periods of REM sleep alternate with non-REM sleep,
starting about 90 minutes after dozing off and continuing throughout the night.
Studies show that heavy drinking (more than four drinks) decreases REM sleep in
the first half of the night. According to Dr. Ebrahim, lack of enough REM sleep
may have a negative effect on concentration, motor skills, and memory during the
As the night goes on, sleeping under the influence causes
more problems. The quality of sleep is disrupted, and people often wake up in
the middle of the night as the effects of alcohol wear off. Having two to four
(or more) drinks before bedtime also reduces the total amount of REM sleep.
The Next Day
People who drink close to bedtime may wake up tired and
cranky—and not only those who stayed out until 3 a.m. Especially if you had
more than one or two drinks, you may have symptoms
of sleep deprivation the next day, including drowsiness, moodiness, and
trouble focusing. You may take longer to finish tasks, make more errors at work
or school, and be more prone to careless accidents.