Does eating late raise your sleeping heart rate?

On average, sleeping heart rate ran slightly above members' own usual level on the night of a logged late meal or heavy late meal. After a logged heavy late meal, it averaged 1.1 bpm higher (likely between 0.7 and 1.5 bpm). After a logged late meal, it averaged 0.7 bpm higher. After a logged late snack, it averaged 0.2 bpm higher (likely between 0.3 bpm lower and 0.6 bpm higher), which includes no change.

How much does sleeping heart rate rise after a late meal?

Sleeping heart rate rose by a small average amount on the night of a logged late meal. In a small study of healthy people, eating raised heart rate, and a large meal raised cardiac output more and for longer than a small one [1].

A late-eating day was a day the member tagged by hand as Heavy Late Night Meal, Late Night Meal or Late Night Snack in the app, counted as three kinds of meal. The tag's time had to fall after the member woke that morning and before they fell asleep that night, and the tag had to be saved before the app first recorded that night's sleep. Tags with no time, tags placed in the night before, tags the app adds on its own and automatic tags a member later changed were not used. Counted days of one kind from one person were at least 17 days apart. Unless the member sets an exact time, the app saves a tag at the middle of the part of the day they pick, such as late evening or night. So a counted tag shows that the meal came before sleep, not how long before.

The personal baseline was the member's average sleeping heart rate over the 14 nights before the logged day, from at least 10 valid nights recorded on the same ring and firmware version. Night one was the night of the logged meal, and night two the following night. Each was compared with that baseline and counted only with a valid reading on the same ring and firmware version.

Days without a late-meal tag were not treated as days with an early dinner, because members do not tag every meal. Each logged day is compared only with the same person's own nights before it. Each person counted equally, however many late-eating days they logged; the uncertainty ranges resampled whole people.

In the figure, each average change on the following night was smaller than on the night of the meal. The analysis did not test whether that drop was more than chance. Part of the following night's rise may come from things that often go with a late meal, such as drinks. The analysis did not check this.

The heavy late meal and regular late meal ranges overlap, so their order is not certain. In a stricter version counting only logged days with a valid reading on every baseline night, the rises were larger for every kind of late eating. On the night of the meal, they kept the same order.

How does a late snack compare with a late meal?

A logged late snack went with a smaller change in sleeping heart rate than either kind of late meal, and little change on the following night. On that night it averaged 0.1 bpm higher (likely between 0.4 bpm lower and 0.5 bpm higher), which includes no change. That average covers 505 members.

After a logged late meal, the following night averaged 0.6 bpm higher (likely between 0.2 and 1.0 bpm). That average covers 710 members. In a stricter version kept to members who logged late meals on several days, that rise was smaller.

What do other studies say about meal timing and heart rate?

Research on meal timing has looked at heart rate in other settings. Adults who took up more of a set of circadian habits, including time-restricted eating, showed improved sleep consistency, resting heart rate, and heart rate variability [2]. A planned randomized trial of time-restricted eating lists resting heart rate and heart rate variability among its secondary outcomes [3]. Neither study followed the night after a late meal. This analysis adds the night of a logged late meal and the following night, each compared with the same members' own usual level.

What this analysis can't tell you

Nobody was assigned a meal time, so the results cannot show that eating late caused the rise. The analysis had no record of alcohol, stress, exercise, or travel that evening, so it cannot separate their effects from the meal's. Members tag only some meals, so the analysis could not compare late eating with early dinners. A counted tag shows only that the meal came before sleep, so the analysis cannot tell whether eating closer to bedtime matters more. Members who log late meals only the next morning are not represented. The analysis followed only the night of the meal and the following night, so it cannot say when heart rate returned to its usual level. Each kind of late eating came from a partly different group of members, and comparisons between kinds were not tested directly.

Frequently asked questions

Does a late snack count the same as a late meal?

A late snack went with a smaller average change in sleeping heart rate than either kind of late meal in these members. Members chose the tag themselves, so the line between a snack and a meal was theirs to draw. Two people eating the same food could tag it differently. The analysis had no record of what or how much anyone ate.

Is sleeping heart rate the same as resting heart rate?

No, sleeping heart rate is not the same as resting heart rate. 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. Every number on this page compares sleeping heart rate with each member's own usual sleeping level.

Who should not read this as being about them?

These averages may not fit anyone whose nights are shaped by shift work, travel across time zones, or a diagnosed heart or sleep condition. The analysis recorded none of these. The group was members who chose to log late meals by hand, and their evenings may differ from those of people who do not. A sleeping heart rate far from your own usual level may be worth raising with your clinician.

References