Alcohol and health: what the glass really costs

The end of the healthy glass

For decades it was said: a glass of red wine protects the heart. The curve that showed it had a flaw: the abstainers in the studies were often former drinkers or sick people, which made non-drinkers look worse. Newer analyses with genetic methods show: there is no protective effect, and the risk for high blood pressure, atrial fibrillation, stroke and cancer rises from the first glass. Health authorities in several countries have changed the recommendation since 2023: no healthy amount, as little as possible. Canada names two drinks a week as the limit for low risk.

What alcohol does to sleep

Alcohol makes you tired and lets you fall asleep faster, which is why it persists as a sleep aid. Then it wrecks the night: it suppresses REM sleep in the first half, fragments the second, raises pulse and body temperature, lowers heart rate variability and wakes you around three when it is broken down. Two glasses in the evening cost 10 to 20 percent of sleep quality in tracker data. Whoever wants to sleep better has the biggest single lever in alcohol.

Heart, brain, cancer, weight

Alcohol raises blood pressure dose-dependently and is a main cause of atrial fibrillation. It shrinks the brain: at just one glass a day brain volume is measurably smaller in imaging data, and alcohol is a risk factor for dementia. It is a confirmed carcinogen for mouth, throat, esophagus, liver, bowel and breast; for breast cancer the risk rises by about seven percent with every daily glass. And it delivers seven calories per gram without satiating, stops fat burning as long as it is being broken down and lowers the threshold for eating the next day.

What a month without brings

Studies on Dry January show after four weeks: blood pressure falls by about 5 mmHg, liver fat by 15 percent, insulin resistance improves, weight falls by one to two kilos, sleep and concentration improve, and most participants still drink less six months later than before. A month of abstinence is the best test of how much alcohol acts in your own life.

If you drink

With food, because absorption is slower. Slowly, one glass an hour, with water in between. Two alcohol-free days in a row per week so the liver regenerates. Not as a sleep aid, not against stress, not alone. And count honestly: one drink is 125 milliliters of wine or 300 of beer, not what fits in a large glass. The cinalia blood alcohol calculator shows how long an evening stays in the blood.