Your resting heart rate changes from day to day mostly because of sleep, alcohol, hard exercise, stress, heat, hormones and illness. A shift of a few beats per minute is common, while a rise that lasts several days, especially with a fever or feeling run down, often means your body is dealing with something.
Here’s what resting heart rate is, what moves it, and how to read your own numbers.
What resting heart rate is
Resting heart rate is how many times your heart beats in a minute while you’re still and relaxed. The American Heart Association, Mayo Clinic and Cleveland Clinic all give 60 to 100 beats per minute as the normal range for most adults. Fit people often sit lower, and some athletes are in the 40s.
That range is wide, and people really do spread across it. In a study of more than 92,000 Fitbit wearers, the average resting heart rate was 65, but individuals ranged from 40 to 109. Two healthy people can differ by dozens of beats.
What the same study also found is that each person’s own number is fairly steady. That’s what makes day-to-day changes worth looking at.
What changes it from one day to the next
Illness and fever. Fighting an infection raises your heart rate. In one study of young adults with acute infections, heart rate went up about 8.5 beats per minute for each degree Celsius of fever, and stayed up even while they slept. Wearables pick this up:
- A Fitbit study of 200,000 people found that the share of users with a raised resting heart rate and more sleep tracked flu-like illness across US states.
- In a Stanford study of smartwatch data, most people who got COVID-19 had changes in heart rate, steps or sleep, often before or at the start of symptoms.
Alcohol, caffeine and smoking. Cleveland Clinic lists all three as raising heart rate. A drink in the evening often shows up as a higher overnight heart rate.
Hard exercise. A tough workout can keep your heart working harder into the next day. The resting side of your nervous system takes up to 24 hours to recover after easy exercise and 48 hours or more after hard sessions. Over weeks and months, regular exercise tends to bring resting heart rate down.
Stress and emotions. Feeling stressed or anxious raises heart rate, and feeling calm lowers it, as Cleveland Clinic and the AHA both note.
Heat. Warmer air can raise your resting heart rate, according to the AHA. The Fitbit study above also saw a small seasonal swing, lowest in July and highest in January.
Sleep. In the Fitbit study, how long people slept on average was linked to their resting heart rate.
The menstrual cycle. In a study of 91 women wearing wrist sensors, pulse during sleep was about 2 beats higher around ovulation and nearly 4 beats higher in the middle of the luteal phase than during menstruation.
Medications. Some medicines change heart rate. The AHA gives beta blockers as an example that slows it, and too much thyroid medicine as one that can speed it up.
How and when it’s measured. Body position matters: your heart beats faster standing than lying down. The AHA suggests checking your pulse in the morning before you get out of bed, and not within an hour of exercise, caffeine or a stressful moment. Wearables estimate resting heart rate from the times you’re still, often overnight, so a restless night can nudge it too.
How to read your own trend
Compare with your own recent average. Since people differ so much, the useful question isn’t whether 62 is good. It’s whether 62 is higher than your last two weeks.
Expect some noise. For most people in the Fitbit study, resting heart rate stayed fairly steady from week to week. But 20 percent had at least one week where it swung by 10 beats or more, so bigger jumps happen too.
Look for a pattern over days. One high morning after a late night out isn’t much to go on. Three or four days up by several beats, with no obvious cause, is more worth noticing. If you also feel run down, or your HRV is down at the same time, your body may be fighting something off.
Line it up with what you did. Check the high days against drinks, hard workouts, poor sleep, travel or a hot week. Often the cause is plain once you look.
Watch the long trend. Over months, a resting heart rate that slowly comes down tends to go with better fitness. A slow climb is something to keep an eye on.
This isn’t medical advice (see our health disclaimer). If your resting heart rate is above 100 or below 40, and especially if it comes with a pounding heart, dizziness, shortness of breath or chest pain, talk to a doctor.
How Voke shows resting heart rate
Voke reads resting heart rate from Apple Health or Google Health. The History tab shows it day by day over the last 7 days, 30 days or year, with your latest value and how far it is from your average over the earlier days. From the Heart screen you can open a single day and drag across your heart rate by the minute or by the hour, with steps underneath, to see what was going on when it rose. If your heart rate stays high while you’re sitting still, Voke notes it in your Feed, as explained in what “while inactive” means. Voke shows what your device recorded. It doesn’t diagnose anything.
Sources
- American Heart Association: All about heart rate
- Mayo Clinic: Heart rate: What’s normal?
- Cleveland Clinic: Heart rate
- Quer et al., PLOS One, 2020: Inter- and intraindividual variability in daily resting heart rate
- Karjalainen and Viitasalo, Archives of Internal Medicine, 1986: Fever and cardiac rhythm
- Radin et al., Lancet Digital Health, 2020: Harnessing wearable device data to improve state-level real-time surveillance of influenza-like illness
- Mishra et al., Nature Biomedical Engineering, 2020: Pre-symptomatic detection of COVID-19 from smartwatch data
- Stanley, Peake and Buchheit, Sports Medicine, 2013: Cardiac parasympathetic reactivation following exercise
- Shilaih et al., Scientific Reports, 2017: Pulse rate measurement during sleep using wearable sensors, and its correlation with the menstrual cycle phases