# Real-world effects of alcohol on heart rate, sleep, and physical activity by age and sex

## TL;DR

Drinking alcohol increases heart rate and disrupts sleep and activity, with stronger effects in younger people and women, but these effects can be lessened by drinking earlier and sleeping longer.

## Contribution

This study provides population-level evidence on alcohol's acute effects on physiology and behavior, stratified by age and sex, using real-world wearable data.

## Key findings

- Alcohol increases resting heart rate and decreases heart rate variability during sleep in a dose-dependent manner.
- Females and younger adults experience stronger physiological disruptions from alcohol compared to males and older adults.
- Drinking earlier, sleeping longer after drinking, and reducing activity can mitigate alcohol's adverse effects.

## Abstract

Alcohol consumption acutely disrupts physiology and behavior. Yet, the modifying effects of age, biological sex, and health behaviors are not well understood. In this retrospective cohort study, we analyzed 5,109,185 person-days from 20,968 participants and fit generalized additive models to estimate within-person associations between alcohol intake and nocturnal resting heart rate (RHR), heart rate variability (HRV), sleep duration, and next-day physical activity. Models were stratified by age and sex, and adjusted for drinking frequency, body mass index, weekday/weekend, and season, and accounted for between-person differences via person-mean centering. We also assessed whether drinking earlier in the day, longer post-drinking sleep, and reducing physical activity attenuated disruptions. Acute alcohol consumption was associated with dose-dependent increases in nocturnal RHR and reductions in HRV, alongside decreases in sleep duration and next-day physical activity. These changes were more pronounced in females than males and in younger than older adults: consuming one drink more than personal average, compared with one less, was associated with an increase in RHR by 2.8 bpm (99.9% CI: 2.7, 2.9) in females and 2.4 bpm (99.9% CI: 2.3, 2.4) in males, while HRV declined by 3.8 ms (99.9% CI: -4.1, -3.5) in females and 3.3 ms (99.9% CI: -3.5, -3.1) in males. Drinking earlier in the day, obtaining longer post-drinking sleep, and reducing activity each reduced these effects. Alcohol consumption acutely disrupts cardiovascular regulation, sleep duration, and next-day physical activity, with stronger disruptions in females and younger adults. Behavioral modifications may mitigate these disruptions.

We set out to understand how a night of drinking changes heart rate, sleep, and next-day physical activity in everyday life, and whether these changes might differ by age and biological sex. Using data from nearly 21,000 adults who wore a wearable sensor, we compared each person’s nights with alcohol to their own nights without alcohol. After drinking, resting heart rate during sleep was higher, heart rate variability was lower, people slept less, and they were less active the next day. These dose-related changes were larger in females than males, and larger in younger than older adults. We also looked for simple habits that might lessen these effects. Drinking earlier in the day, getting more sleep after drinking, and keeping exercise lighter on drinking days were each linked to smaller adverse effects. Our findings offer population-level evidence that even low volumes of drinking can affect nightly recovery and next-day physical activity, and offer practical guidance to lessen some of the adverse effects of drinking for people who choose to drink.