Coffee and heart rhythm, steps, sleep and glucose in 100 adults
What it found
In 100 adults, drinking caffeinated coffee did not significantly increase premature atrial contractions.
It was linked to more premature ventricular contractions, more daily steps, less sleep and no clear change in blood glucose.
What they found
Studies in people
Premature atrial contractions
On coffee days, people had an average of 58 premature atrial contractions per day, compared with 53 on caffeine-free days. The authors say this difference was not statistically significant.
Premature ventricular contractions
Coffee days were linked to an average of 154 premature ventricular contractions per day, compared with 102 on caffeine-free days. The authors say this may be a real effect, especially in people who drank more than one coffee drink per day.
Physical activity
People took an average of 10,646 steps on coffee days, compared with 9665 steps on caffeine-free days. That is about 1000 more steps per day.
Sleep
People slept an average of 397 minutes per night on coffee days, compared with 432 minutes on caffeine-free days. That is about 36 minutes less sleep per night.
Blood glucose
Average daily glucose was 95 mg per deciliter on coffee days and 96 mg per deciliter on caffeine-free days. The authors found no clear relationship between coffee and daily glucose levels.
Caffeine metabolism genes
People with gene variants linked to faster caffeine metabolism seemed to have more premature ventricular contractions when they drank coffee. Those with slower metabolism seemed to lose more sleep when they drank coffee.
What the authors conclude
“In this randomized trial, the consumption of caffeinated coffee did not result in significantly more daily premature atrial contractions than the avoidance of caffeine.”
Also in their conclusions
- They conclude that in this trial, drinking caffeinated coffee did not lead to significantly more premature atrial contractions than avoiding caffeine.
- They say their secondary findings suggest coffee may be linked to more premature ventricular contractions and more physical activity but less sleep, and they found no clear link to blood glucose.
- They suggest that an individualized approach to coffee consumption may be the most appropriate way to fit it with personal health goals.
How it was done
Coffee is one of the most commonly consumed drinks in the world, but its short-term health effects are largely unknown. The authors wanted to test the common warning that coffee should be avoided because it may cause heart rhythm problems.
They ran a 14-day randomised trial in 100 adults, mostly in their 30s and 40s. Each person was randomly told by daily text message to drink caffeinated coffee or avoid caffeine on alternating days, while wearing a heart monitor, a wrist activity tracker and a continuous glucose monitor.
What it can’t tell you
- The trial was relatively small and the participants were mostly young and healthy, so the results may not apply to other groups, such as people who already have frequent heart rhythm problems.
- The trial was not blinded, so other things that go along with coffee drinking could have influenced the results.
- The authors could not separate the effects of caffeine from other ingredients in the different types of coffee drinks people consumed.
Who paid
- Funding
- Funded by NIBIB NIH HHS; NHLBI NIH HHS; University of California, San Francisco (from the PubMed record).
- Authors work at
- University of California, Irvine (C.F.); and the University of California, T.J.
The paper
- Title
- Acute Effects of Coffee Consumption on Health among Ambulatory Adults
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Marcus GM, Rosenthal DG, Nah G, et al (2023). Acute Effects of Coffee Consumption on Health among Ambulatory Adults. The New England journal of medicine. doi:10.1056/NEJMoa2204737Free full textPubMed 36947466DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error