Researchers recruited 100 coffee drinkers without heart rhythm irregularities. (Most typically drank about ½ cup to 3 cups of coffee a day.)

For 2 weeks, each participant got a text saying that they should either consume coffee or avoid all caffeine the next day, in random order.

Coffee had no impact on premature contractions of the atria (the heart’s smaller chambers). However, premature contractions of the ventricles (the heart’s larger chambers) were more common on coffee days (154 per day) than on no-caffeine days (102). The participants also took 1,058 more steps and slept 36 fewer minutes on coffee days. Coffee had no impact on daily blood sugar levels.

What to know

Coffee doesn’t boost the risk of premature atrial contractions. Occasional premature ventricular contractions (which may feel like a skipped heartbeat or go unnoticed) are usually harmless.