How alcohol affects sleep

Why do you want to sleep after alcohol?

First of all, alcohol affects the brain and disrupts the normal production of chemicals, on which many processes in the body depend.

So, it is known that a glass or two increases the production of adenosine by the Alcohol and Sleep / Sleep Foundation. This substance tells the brain that the cells of the body are tired, they lack energy and it is time to rest. The more adenosine, the more sleepy you get.

But falling asleep in this case does not mean getting enough sleep.

How alcohol affects sleep

If the level of adenosine increases, then melatonin, a hormone that is responsible for the quality of sleep, regulates the change of its phases and the circadian rhythms of the body as a whole, on the contrary, becomes less. Moreover, it is essential. 50 grams of vodka (200 g of weak wine or 400 ml of beer) is enough to lower melatonin levels T. L. Rupp, Ch. Acebo, M. A. Carskadon. Evening alcohol suppresses salivary melatonin in young adults / Chronobiology International by almost 20%.

For the body, this means the following. The biological clock, which is directly dependent on melatonin, begins to malfunction. The architecture of sleep, that is, the alternation of its main phases, is disrupted.

Sleep normally consists of two phases.

The phase of slow sleep. It occurs immediately after falling asleep and lasts approximately 90 minutes. Slow sleep is similar to anesthesia: the body is as relaxed as possible, the brain is inactive. No dreams, no movements, complete relaxation necessary for physical recovery.
REM sleep phase. Follows a slow one and lasts 5–20 minutes. During this period, the brain is actively working, we have dreams. If slow sleep is necessary rather for the physical recovery of the body, then fast sleep helps the nervous system: relieves mental stress and fatigue, refreshes memory, improves concentration.

They follow each other, two phases - one sleep cycle. On average, we go through five cycles per night. This is enough to feel vigorous and rested in the morning.

But alcoholic sleep is different from normal. After drinking due to a malfunction in the production of melatonin, we fall into deep NREM sleep without dreams. It lasts longer than usual. REM sleep, on the other hand, shrinks or disappears altogether.

As a result, we feel overwhelmed when we wake up after drinking. Reactions are inhibited, it is difficult to concentrate on something, memory fails, nerves go to hell. The reasons are clear: the nervous system simply did not have time to recover.

These are not all sleep disorders that alcohol leads to. Here are a few more.

Morning insomnia. You wake up at or before dawn and can no longer fall asleep, although you have obviously not gotten enough sleep. This is due to the same dropped melatonin levels.
Sleep apnea. This is the name for stopping breathing during sleep. It most often occurs during slow wave sleep, when the muscles relax. And slow sleep, flavored with alcohol, is especially deep.
Frequent awakenings in the second half of the night. By this time, the body begins to actively get rid of processed alcohol through the kidneys and bladder.

How to drink to get enough sleep

The best way to get enough sleep is to avoid drinking alcohol at night. If for some reason you cannot refuse alcohol, follow the safety rules.

1. Don't drink too much

Doctors define the norm Alcohol Poisoning / Mayo Clinic quite clearly: no more than one drink a day for women and men over 65 years old and no more than two drinks for men younger.

"One drink" in this case is:

355 ml of beer with a strength of about 5%;
237-266 ml malt liqueur, about 7% ABV;
148 ml of wine with a strength of about 12%;
44 ml of alcohol with a strength of 40%.

2. Drink slowly

This is necessary so that the liver has time to neutralize and remove alcohol before it seriously affects the biochemical processes in the body.

3. Have a snack

Food in the stomach slows down the absorption of alcohol and thus makes it easier for the liver to function.

4. Drink no later than 3-4 hours before bedtime

During this time, the level of melatonin will return to normal, which means that the sleep will be healthy.

5. Don't mix alcohol with sleeping pills

Alcohol depresses Facts about alcohol overdose (or “Alcohol poisoning”) / U. S. National Institute on Alcohol Abuse and Alcoholism breathes like most sleeping pills. This combination is extremely dangerous, as it can lead to respiratory arrest.

This material was first published in July 2017. In July 2020, we updated the text.