The guide

What alcohol does to your heart rhythm and blood pressure

By GyroscopeUpdated November 15, 20269 sources

Alcohol works your heart harder the night you drink, and over years it pushes it toward a ragged rhythm and higher blood pressure. A drink a day went with a 16% higher risk of atrial fibrillation in 107,845 Europeans, and blood pressure rose in a straight line with no threshold. The heart benefit people used to talk about came from a counting mistake.

The heart is where the “a glass of red is good for you” idea lived longest. Doctors told patients a drink might raise their good cholesterol, and studies seemed to show fewer heart attacks in light drinkers. What they mostly showed was that light drinkers were healthier to begin with, and that sick people had quit. Why one drink a day looked healthy has that story.

The night you drink

Your heart beats faster while your body clears alcohol, even as you sleep. In 20,968 WHOOP members, a night with one drink more than their usual, against one less, came with a sleeping heart rate 2.4 beats higher in men and 2.8 in women, and lower HRV. WHOOP paid for that study. What your watch or ring sees has the full picture.

For people who already have atrial fibrillation, a drink can set off an episode. In a 2021 study, 100 people with AFib wore a heart monitor and an ankle sensor that measures alcohol through the skin for four weeks. An episode was twice as likely within four hours of one drink, and more than three times as likely after two or more.

The habit

Atrial fibrillation, or AFib, is a heart rhythm where the top chambers quiver instead of beating. In a 2021 study that followed 107,845 people in Europe for about 14 years, each daily drink of 12 g raised the risk of AFib by 16%. Beer, wine and spirits all did it. The same study found lower heart failure risk at small amounts, which is why alcohol and the heart is a tangled story. But for rhythm, more alcohol was always worse.

The best evidence is a trial. In 2020 doctors in Australia took 140 regular drinkers with AFib, averaging about 17 Australian drinks (12 g each) a week, and asked half to stop. Over six months, AFib came back in 53% of the group that stopped, against 73% of the group that carried on. The ones who quit also spent less time in AFib.

Blood pressure

Alcohol raises blood pressure, and nobody has found an amount where it starts. A 2023 analysis of seven studies following 19,548 adults for about five years found the top number ran 1.25 points (mmHg) higher at 12 g a day and 4.9 higher at 48 g, against people who didn’t drink, in a straight line. The genetic study of half a million Chinese adults found the same thing in a way that’s hard to blame on lifestyle: men whose genes made them drink more had higher pressure, step by step.

It comes down fast when you stop. In 94 moderate to heavy drinkers who took a month off, systolic pressure fell 6.6%. bloodpressure.guide has the details on your numbers, and blood pressure, with and without has the chart.

What about heart attacks?

This is where the old benefit claims came from, and where the newer evidence hurts them most. In 261,991 Europeans, people with a gene variant that made them drink less had 10% lower odds of coronary heart disease, at every level of drinking. In 371,463 people in the UK Biobank, the genetic analysis showed light drinking nudged heart risk up a little and heavier drinking raised it fast. The Chinese genetic study found no protection against stroke, and no clear effect on heart attacks either way.

The best evidence says a drink doesn’t protect your heart, and more drinks hurt it. If you want your heart to be healthier, the things that work are on vo2max.guide and bloodpressure.guide.