Which everyday events raise your sleeping heart rate the most?

A logged sick day came with the largest rise in sleeping heart rate on the night that followed, 2.6 bpm above members' usual level, with a flight next at 1.9 bpm. Smaller rises came after a late meal (1.1 bpm) and a heavy late meal (0.9 bpm). A logged drink came with a rise of 0.8 bpm, and a stressful day with a level about 0.4 bpm lower, which is no clear change. Staying up late (0.3 bpm) and late caffeine (0.3 bpm) also came with no clear change.

Which days came with the biggest rise in sleeping heart rate?

A logged sick day came with the biggest rise in sleeping heart rate on the night that followed, then a flight and jet lag. Jet lag had fewer members, so its place in the order is less certain. Researchers studying nighttime heart rate have listed exercise, too little sleep, excess alcohol, certain foods, socializing, and air travel among the daily stressors that influence it [1].

Jet lag came with a rise of 1.5 bpm (likely between 0.6 and 2.5 bpm). The sick day's range sat entirely above the ranges for a late meal and a drink. It overlapped the ranges for a flight and jet lag, and a flight's range overlapped those for a late meal and a drink. The analysis did not test these differences directly. After a headache, a party, a late snack, or working late, each range included no change.

A heavy late meal's rise was likely between 0.1 and 1.7 bpm, just above no change, across 219 members. Its range overlaps the late meal's, so this does not show a smaller rise after a heavy late meal.

Ultrahuman's article on illness found a rise of 3.3 bpm on the night members slept after a logged sick day. That article used its own baseline and tag rules, so its number is not directly comparable with this one. Ultrahuman's article on alcohol, which had more members, found a rise of 0.6 bpm on the night members slept after a logged drinking day.

How was each night compared with a member's usual heart rate?

Each logged day was compared with the same member's own recent nights, using the rules below.

An event day was a calendar day the member tagged by hand in the app with one of 13 groups of tags, such as Sick, any alcohol tag, Heavy Late Night Meal, Long Flight or Stressed. The tag had to be saved before the app first recorded the following night's sleep, and tags the app adds on its own were not used. Counted days of one group from one person were at least 16 days apart. The personal baseline was the member's average sleeping heart rate over the 14 nights before the event day, from at least 10 valid nights recorded on the same ring and firmware version.

Each group's result is the night members slept after the event day, compared with that baseline. A night counted only with a valid reading on the same ring and firmware version. Members were sampled separately for each group, so rarer events had enough people to measure. Days without a tag were not treated as event-free, and each event day is compared only with the same person's own nights before it.

Within each group, each person counted equally, however many event days they logged; the uncertainty ranges resampled whole people.

Stricter versions of the rules tested the ranking. One needed a valid reading on every baseline night. Another left out logged days whose baseline held another logged day of the same kind. A third kept only tags saved with a time of day. In each version, a sick day still came first and a flight stayed second, but the order of the other days changed. When every baseline night needed a valid reading, the stressful-day average moved from slightly below to slightly above the usual level, which fits its range including no change.

Do stress, late caffeine, and staying up late raise sleeping heart rate?

A stressful day, late caffeine, and staying up late came with no clear rise in sleeping heart rate on the night that followed. Each range includes no change. After staying up late, sleeping heart rate was about 0.3 bpm higher (likely between 0.2 bpm lower and 0.8 bpm higher). That result covered 357 members. After late caffeine, it was about 0.3 bpm higher (likely between 0.4 bpm lower and 1.1 bpm higher). That result covered 240 members. In a study that followed three healthy volunteers for up to four years and analyzed each person on their own, self-reported stress went with a lower average nighttime heart rate [1]. This analysis cannot say why stress came with no rise here.

What this analysis can't tell you

The analysis cannot say that a logged day caused the change, because a sick day or a flight often brings other changes the app never recorded. Members chose which days to log, so the baseline nights may include unlogged drinks, late meals, or colds, which could make the rises measured here smaller. The drink group counted any alcohol tag, so it may mix light and heavy drinking days. Members were sampled separately for each kind of day, so the ranking compares different, partly overlapping sets of members. The analysis measured only the night after each logged day, so it cannot say how long any rise lasted. Ultrahuman's articles on illness and alcohol follow those rises for longer. Travel across time zones was not accounted for, which matters most for flights and jet lag.

Frequently asked questions

Is sleeping heart rate the same as resting heart rate?

No. Sleeping heart rate is your average heart rate across the whole night's sleep. Resting heart rate is a separate measure, covered in Ultrahuman's resting heart rate explainer, so the numbers here don't apply to it.

Does a party raise sleeping heart rate as much as a drink?

A logged party came with a smaller average change than a logged drink, though the two ranges overlap. After a party, sleeping heart rate was about 0.1 bpm higher (likely between 0.8 bpm lower and 1.0 bpm higher), which includes no change. The drink's rise stayed above no change. The analysis did not test the difference between the two.

Who should not read these results as being about them?

People with a diagnosed heart condition, or on medicines that change heart rate, were not looked at separately, so these averages say nothing specific about them. People who log the same thing on most days are not well described either, because their baseline would include those days too. The analysis covered adults only. A sleeping heart rate far from your usual level may be worth discussing with a clinician.

References