Beer, wine or gin: how alcohol affects sleep – 12/01/2023 – Science

One thing is undeniable: alcohol can actually help you fall asleep. Depending on how many beers it takes after work to forget the problems accumulated throughout the day, the first half of the night can actually have a feeling of relaxation worthy of a coma.

Through the stomach, alcohol enters the blood and necessarily takes one of two routes: towards the liver or towards the brain. In the latter, alcohol first causes the release of serotonin and dopamine, which lead to feelings of reward and relaxation. The calming and sleep-inducing effect is also felt through other messenger substances, neurotransmitters.

However, after about 4 to 5 hours, this effect ended. From that point on, the quality of sleep is noticeably worse or we are no longer able to sleep at all. “This occurs because alcohol breaks down into acetaldehyde in the body”, explains gastroenterologist Helmut Seitz, who researches the effects of the substance on the body.

Acetaldehyde causes adrenaline and cortisol — the “stress hormone” — to be released in the brain, explains Seitz. “It all makes us wake up and stay awake.”

Poor quality alcohol makes sleep even worse

Whether it’s wine, beer or gin and tonic – it doesn’t matter what drink we drink at night: the alcohol in it will disturb our sleep. But it’s worth mentioning: low-quality alcoholic drinks can make things even worse.

“A cheap wine may contain additional substances, such as flavorings, fusel oils and long-chain alcohols,” says the researcher. This can cause nausea and headaches, making the next day even more difficult.

The dose makes the poison

But even the purest, highest-quality vodka converts to the toxic substance acetaldehyde. The subsequent flood of adrenaline and cortisol may not wake us up, but it ends up disturbing the so-called REM phases of sleep.

The degree of interference does not depend so much on the quality of the drink, but on the quantity. “The higher the dose of alcohol, the greater the disruption of REM sleep phases in the second half of the night,” explains Henrik Oster, professor of neurobiology at the University of Lübeck, Germany. As a rule, sleep quality noticeably deteriorates at rates of 0.2 to 0.3 parts per thousand in the blood, says Oster.

The moment at which such blood alcohol levels are reached depends on several factors: gender, height and body weight, whether the person has a full or empty stomach or whether they take any medication. But one thing is certain: it’s not difficult to reach 0.2 parts per thousand — just two glasses of wine can be enough.

How REM sleep affects our physical and mental health

When we dream, we move not only our eyes, but our entire body. These active phases of sleep are called REM sleep (short for rapid eye movement). How and why we dream remains a mystery in science.

What is certain, however, is that the REM sleep phases are crucial to our physical and mental health. For babies, REM sleep represents a large part of sleep – something fundamental for the development of the little ones’ brain. During these phases, the parts of the brain that are activated differ from those when we are awake.

“Alcohol suppresses the REM sleep phases,” says Oster. People whose REM sleep is regularly interrupted have difficulty concentrating and suffer from memory problems. According to a 2020 study, REM sleep disorders are also associated with a higher mortality rate.

According to specialist Seitz, the first thing that visibly improves in the life of someone who stops drinking is sleep. “You feel more relaxed, more balanced, and better able to tackle the day. And you’ll like it.”