When in the Night Does Your Heart Rate Hit Its Lowest and Does It Matter?

Have you ever looked at your tracker and wondered when in the night your heart rate hits its lowest, and whether that number means anything? Here is what research says about the nightly dip, what nudges it up or down, and a 7-day log you can run yourself.

In this article

1. Does your heart rate really drop while you sleep?
2. When during the night is your heart rate lowest?
3. What shifts your lowest heart rate during sleep?
4. Why is sleep the best time to read resting heart rate?
5. Does the timing of your nightly low matter?
6. How can you track your nightly low for a week?
7. Who should be careful with heart rate numbers?
8. Frequently asked questions
9. Final thoughts
10. Sources and further reading

Does your heart rate really drop while you sleep?

Yes, for most healthy people heart rate is lower during sleep than during the day, because the body shifts toward a calmer, recovery-oriented state. This overnight fall is sometimes called nocturnal dipping, and it is the reason the lowest heart rate during sleep is usually lower than any daytime reading.

The Sleep Foundation describes how heart rate and breathing slow during light non-REM sleep (stage N2), and pulse and breathing rate decrease further in deep sleep (stage N3). A 2023 study in PLOS Digital Health (Speed and colleagues) put numbers on it: across 433 healthy adults wearing Fitbit Charge 4 devices for up to three months, mean night-time resting heart rate was 50.5 beats per minute (bpm), against 54.5 bpm in the daytime.

Alcohol with dinner can interfere with this dip, a topic covered in how alcohol changes your sleep quality.

The dip varies a lot from person to person

Night-time resting heart rate in that study ranged from 32.6 to 89.8 bpm across participants, so your number is more useful compared with your own history than with someone else's.

A 2021 Journal of Sleep Research study (Cosgrave and colleagues) used polysomnography in young adults who rated themselves good or poor sleepers. Poor sleepers had a higher heart rate and a smaller drop from waking to sleep. The groups were self-reported, so it describes a pattern, not a test.

When during the night is your heart rate lowest?

The lowest heart rate of the night most often falls somewhere between the middle of the night and the early morning, but the exact time differs between people and between nights. No source I found supports one clock time for everyone, so be wary of any single hour quoted online.

The Journal of Sleep Research study reported that the lowest heart rate points occurred around the mid-point of the night, consistent with the lowest point of core body temperature. In the wearable study, 53% of the lowest readings occurred between 3 a.m. and 7 a.m., and the authors suggested measuring true resting heart rate in that window for most people. That also means 47% fell at other times, so your own low may land earlier in the night.

Why the timing differs

The Sleep Foundation notes that deep sleep is most abundant in the first half of the night, while REM periods get longer in the second half. Bedtime and the body clock probably shift where a person's low lands, but the sources I opened do not say how much, so treat this as an informed picture, not a rule. The wearable study's authors also noted that findings depend on that specific device and may not carry over to other wearables.

What shifts your lowest heart rate during sleep?

Alcohol and a warm bedroom both have some research linking them to a higher heart rate during sleep, while stress, late meals, illness and hard training are commonly suspected but less well documented. What matters is spotting what moves your own number.

Alcohol

A 2025 observational study in Nutrients (Strüven and colleagues) followed 40 healthy adults with smartwatches for nine days. After three evenings of moderate alcohol, average nocturnal resting heart rate rose from 63.6 to 66.6 bpm and normalised in the days after. The smartwatch has limits compared with lab sleep testing.

A warm bedroom

A 2025 observational study in BMC Medicine (O'Connor and colleagues) tracked 47 adults aged 65 and over in Queensland, Australia, through a summer. Warmer bedrooms were linked with lower HRV and a tendency toward a higher heart rate. The group was small and likely used to the heat.

Stress, meals, illness and training

A 2024 Frontiers in Sleep paper acknowledges that heart rate can be modified by stress, anxiety and pain. The sources I could open do not quantify the effect of late meals, illness or training on the nightly low, so treat these as things to log and test, not proven drivers.

Stress is worth its own look, and how stress affects your heart rate goes into the daytime picture. Meal timing is another one to test, covered in whether eating late at night hurts your sleep.

Why is sleep the best time to read resting heart rate?

Sleep is a good time to read resting heart rate because you are still, relaxed and free from caffeine, movement and stress, which makes the number steadier and easier to compare day to day. A daytime reading can be nudged up by a coffee, a stressful email or a flight of stairs minutes earlier.

The NHS describes a normal resting heart rate as 60 to 100 bpm for adults, yet the healthy adults in the wearable study averaged in the low 50s overnight. That study also found heart rate had stabilised after 4 minutes of inactivity in most people, but in over 13% it had not settled after 15 minutes, so a quick daytime check can mislead.

Does the timing of your nightly low matter?

Possibly, but nobody has shown that the clock time of your lowest heart rate predicts your health or recovery. Treating the timing of the nightly low as a recovery marker is an emerging idea with thin published evidence, and it is not an established clinical marker.

The wearable study did not examine whether timing relates to health outcomes or recovery, and the Journal of Sleep Research paper looked at heart rate level, not the time of the low. The timing is interesting to observe and unproven as a signal.

What is better studied: the size of the dip

A smaller overnight fall in blood pressure is called non-dipping. A 2024 Frontiers in Sleep paper (Hilmisson and colleagues) found that during stable non-REM sleep, blood pressure dippers averaged a minimum heart rate of 56 bpm against 59 bpm in non-dippers. That is a group-level association in research. It does not mean a tracker can tell you your blood pressure pattern.

How can you track your nightly low for a week?

You can track your nightly low by logging bedtime, last meal and alcohol each evening, then writing down the lowest heart rate your tracker shows each morning. A week gives you a first look at your own pattern, and a quiet week with no change is a useful result too.

Sort the nights into higher than usual and typical, and see what each group shares. If the higher nights follow alcohol or a warm room, that matches what the group studies found. If not, your pattern may simply differ.

Who should be careful with heart rate numbers?

Anyone with a heart condition, on heart rate-altering medicine, pregnant, or worried about symptoms should rely on a healthcare professional, not a tracker, to interpret heart rate. Wearables are not medical devices, and an unusual number is a reason to ask, not to self-diagnose.

Some medicines, such as beta blockers, deliberately slow the heart, so a different baseline is expected. See a doctor if you have chest pain, fainting, dizziness or shortness of breath, and do not wait to see whether a tracker agrees.

Frequently asked questions

What is a normal lowest heart rate during sleep?

There is no single normal figure. In a 2023 wearable study of 433 healthy adults, mean night-time resting heart rate was 50.5 bpm, but individual values ranged from about 33 to 90. Compare your own nights over time instead of matching a target, and ask a clinician about readings that worry you.

Is a lower heart rate during sleep always better?

Not necessarily. A lower reading is common in fit people, but natural variation is wide, and a low number alone says little about health. If a slow heart rate comes with dizziness, fainting or breathlessness, speak to a doctor. Otherwise, trends matter more than one night.

Does my heart rate go up during REM sleep?

Heart rate can vary between sleep stages, but the sources I opened for this article did not give a reliable figure for REM, so I will not quote one. Small rises and falls overnight on your tracker are generally part of normal sleep cycling. Ask a clinician if you are concerned.

Why is my lowest heart rate higher on some nights?

Alcohol and a warm bedroom both have some study support. A 2025 study found alcohol raised average nocturnal resting heart rate by about 3 bpm, and a 2025 study found warmer bedrooms linked with a higher heart rate in older adults. Stress, late meals and illness are plausible too, but less well documented.

Can I use the time of my lowest heart rate to judge recovery?

Not reliably. The timing of the nightly low as a recovery marker is an emerging idea with thin published evidence, and no source I found shows it predicts health outcomes. It is fine to observe it, but base decisions on how you feel and on longer-term trends in your own data.

Should I check resting heart rate at night or in the morning?

The overnight low is steadier because you are still and unaffected by caffeine or activity. If you check by hand, sit quietly for at least 4 minutes first, since heart rate had settled by then in most people in the wearable study. Use the same method each time.

Final thoughts

Here is the short recap.

• Heart rate usually falls during sleep, and the lowest reading tends to appear between the middle of the night and the early morning, with no fixed time.
• Alcohol and a warm bedroom have some research linking them to a higher heart rate during sleep, so they are good things to log.
• The timing of your nightly low is an emerging idea with thin evidence, so focus on your own trend over weeks, not one reading.

Your turn: When does your tracker say your heart rate is lowest, and what do you think moves it? Tell us in the comments.

Sources and further reading

1. Speed C, Arneil T, Harle R, Wilson A, Karthikesalingam A, McConnell M, Phillips J. Measure by measure: Resting heart rate across the 24-hour cycle. PLOS Digital Health, 2023.
2. Cosgrave J, Phillips J, Haines R, Foster RG, Steinsaltz D, Wulff K. Revisiting nocturnal heart rate and heart rate variability in insomnia: A polysomnography-based comparison of young self-reported good and poor sleepers. Journal of Sleep Research, 2021.
3. Strüven A, Schlichtiger J, Hoppe JM, Thiessen I, Brunner S, Stremmel C. The Impact of Alcohol on Sleep Physiology: A Prospective Observational Study on Nocturnal Resting Heart Rate Using Smartwatch Technology. Nutrients, 2025.
4. O'Connor FK et al. Effect of nighttime bedroom temperature on heart rate variability in older adults: an observational study. BMC Medicine, 2025.
5. Hilmisson H, Thomas RJ, Magnusdottir S. Cardiopulmonary coupling-calculated sleep stability and nocturnal heart rate kinetics as a potential indicator for cardiovascular health: a relationship with blood pressure dipping. Frontiers in Sleep, 2024.
6. Sleep Foundation. Stages of Sleep: What Happens in a Normal Sleep Cycle?. sleepfoundation.org, accessed 2026.
7. NHS. Supraventricular tachycardia (SVT). nhs.uk, accessed 2026.