Sleeping heart rate: what is normal and what the dip means

A normal sleeping heart rate is lower than your daytime resting heart rate. Clinicians call a drop of at least 10% from your awake average a normal "dip"; for someone who averages 70 beats per minute (bpm) while awake, that means 63 bpm or lower asleep. In a small study of healthy women, average heart rate during sleep was 63 to 67 bpm.

The shape of the night matters as much as the number. Heart rate slows as you fall asleep, reaches its lowest levels in deep sleep, and rises toward waking levels during REM sleep, which gets longer toward morning. A smaller dip than usual is associated with worse outcomes in clinical studies, and night-to-night changes reflect alcohol, illness and recovery. For awake values, see the resting heart rate by age chart.

What is a normal sleeping heart rate?

A normal sleeping heart rate is lower than the same person's awake resting heart rate, usually by 10% or more. There is no single normal number for everyone, because resting heart rate itself ranges from about 40 bpm in trained athletes to 100 bpm. In one study of healthy women, average sleep heart rate across three nights was 63 to 67 bpm.

The best reference is your own pattern. In that same study, a person's minimum heart rate during sleep varied by about 8 bpm from night to night even when training did not change. So read a single night with care, and compare a 7-night average with your usual range.

Awake resting heart rate	A 10% dip means sleeping average at or below	Example
50 bpm	45 bpm	Fit adult
60 bpm	54 bpm	Lower part of normal range
70 bpm	63 bpm	Near the US adult average
80 bpm	72 bpm	Upper-middle part of normal range
90 bpm	81 bpm	Upper part of normal range

Dip definition: Ben-Dov et al., Arch Intern Med 2007, nondipping = (awake minus sleep) divided by awake below 0.1. Values in the table are arithmetic from that definition.

How does heart rate change through the night?

Heart rate follows the sleep stages. It slows in light non-REM sleep, reaches its lowest levels in deep non-REM sleep, and rises to near waking levels during REM sleep. Because deep sleep comes in longer periods in the first half of the night, and REM periods get longer toward morning, the lowest values often appear earlier in the night.

Sleep stage	What happens to heart rate	Where in the night
Stage 1 non-REM (falling asleep)	Heartbeat starts to slow	Start of each cycle, a few minutes
Stage 2 non-REM (light sleep)	Slows further	Most of total sleep time
Stage 3 non-REM (deep sleep)	Slows to its lowest levels	Longer periods in the first half
REM sleep	Rises to near waking levels, more irregular	Longer periods toward morning

Source: NIH NINDS, Brain Basics: Understanding Sleep. A full sleep cycle lasts about 90 minutes on average.

Heart rate variability (HRV) has a night pattern too. In 24-hour recordings of 166 healthy adults, the vagus-related HRV measures peaked at night. That is why many wearables read HRV during sleep. See HRV during sleep for normal overnight HRV.

What does a blunted heart rate dip mean?

A blunted dip, or nondipping, means your heart rate falls by less than 10% from the awake average during sleep. In a study of 3,957 patients referred for 24-hour monitoring, a smaller sleep dip was independently associated with higher all-cause mortality. The lowest tenth of dip size had a 2.67 times higher hazard than the highest tenth.

That study measured patients referred for blood pressure monitoring, many with treated hypertension, so the numbers do not transfer directly to healthy wearable users. It also found that older age, higher BMI, female sex, napping, treated hypertension and treated diabetes were linked to a smaller dip. One night with a small dip means little. A dip that stays small for weeks, especially with other symptoms, is worth raising with a doctor.

What raises your heart rate during sleep?

Alcohol and illness with fever are the best-measured causes of a higher sleeping heart rate. In 4,098 adults, heart rate in the first 3 hours of sleep rose by 1.4, 4.0 and 8.7 bpm after low, moderate and high alcohol intake. During fever, heart rate stayed high even during sleep.

Factor	Measured effect on sleeping heart rate
Low alcohol intake (up to 0.25 g/kg)	+1.4 bpm in the first 3 hours of sleep
Moderate alcohol intake (0.25 to 0.75 g/kg)	+4.0 bpm
High alcohol intake (above 0.75 g/kg)	+8.7 bpm
Fever	About +8.5 bpm per 1 °C rise; stays high during sleep

Sources: Pietilä et al., JMIR Mental Health 2018 (4,098 adults); Karjalainen and Viitasalo, Arch Intern Med 1986 (27 young men with acute infection).

The alcohol study also found that HRV-based recovery fell by 9.3, 24.0 and 39.2 percentage units across the same three doses. If one night stands out, check the evening before. For a pattern of high nights with feeling unwell, see heart rate when sick.

Is a low sleeping heart rate dangerous?

A low sleeping heart rate is usually normal, especially in fit people, because sleep is when heart rate is at its lowest. Trained athletes can have awake resting rates of 40 to 60 bpm, and their sleeping rate is lower still. A low rate becomes a concern when it comes with symptoms, not by the number alone.

See a doctor if a low heart rate comes with daytime dizziness, fainting, unusual tiredness or shortness of breath, or if a partner notices pauses in breathing, loud snoring or gasping during sleep. Also see a doctor for an irregular pulse or palpitations at night. A wearable can show a pattern but can not diagnose a rhythm or breathing problem.

Does sleeping heart rate show recovery?

Sleeping heart rate is a useful recovery signal because it is measured in similar conditions each night: lying still, asleep, without posture changes. A higher than usual sleeping heart rate, together with lower HRV-based recovery, appeared after alcohol in a study of 4,098 adults, and fever keeps heart rate high during sleep.

This is why many recovery scores use the overnight low or a sleeping average as the resting heart rate input. The recovery score guide explains how heart rate, HRV and sleep combine, and the sleep score guide explains the sleep side.

How do you track sleeping heart rate?

To track sleeping heart rate you need a device worn overnight: a watch, ring or chest strap that writes heart-rate samples during sleep. A phone on the nightstand can not measure it. Wear the device snug, keep the same device and look at 7-night averages rather than single nights.

• Fit: A loose band gives gaps and false spikes.
• Same device: Different sensors give different values. Start a new baseline after a device change.
• Context: Log alcohol, late meals and illness, so a high night has an explanation.

How Svanu uses your sleeping heart rate

Svanu reads resting heart rate from Apple Health. When a watch does not write resting heart rate, the app derives it from your heart-rate samples as the lowest 30-minute average during your main sleep, and compares derived values only with derived values.

That value feeds the recovery score, which compares this morning's HRV and resting heart rate with your own recent baseline, plus sleep. The baseline is provisional after 3 nights and full at 7. The sleep score, from 0 to 100, uses duration (50%), stage quality (30%) and bedtime consistency (20%). Every score shows its inputs and what moved it. See how the sleep and recovery scores work in Svanu.