There is no single normal sleeping heart rate number — it depends on age, fitness, and health. In general, heart rate should dip below your daytime resting rate during sleep and rise briefly during REM. Sudden spikes or a persistently high nighttime heart rate are often linked to sleep apnea, caffeine, or alcohol.
Instead of chasing one universal number, the most useful way to think about a normal sleeping heart rate is what this article calls the Dip-and-Recover pattern: across a night of healthy sleep, heart rate tends to fall as the body settles into deeper sleep stages, then rise again toward the lighter stages and waking. The body moves through this cycle roughly every 90 to 110 minutes, alternating between NREM and REM sleep. What matters most for most people is not hitting a specific number but seeing that dip-and-recover shape show up night after night, rather than a heart rate that stays elevated or spikes unpredictably.
Heart rate during sleep is not constant — it shifts as the body cycles through sleep stages. Each sleep cycle lasts roughly 90 to 110 minutes and moves through NREM stages (N1, N2, and N3, or deep/slow-wave sleep) before entering REM sleep, the dream-heavy stage marked by muscle atonia and active emotional processing. Deep NREM sleep dominates the earlier cycles of the night, while REM periods lengthen in the second half of the night. Because these stages involve very different levels of bodily activity, it is expected that heart rate is not the same throughout the night — it is part of a changing pattern rather than a fixed baseline.
"Sleep heart rate" is simply the term for how your heart rate behaves overnight, as opposed to your daytime resting heart rate. Because sleep itself is not a single uniform state, sleep heart rate is better read as a trend across a full night than as one number. The clinical gold standard for measuring sleep, including how the body behaves stage by stage, is polysomnography (PSG) conducted in a sleep lab. Consumer wearables can also track heart rate overnight, but their agreement with PSG is limited: independent research found the Apple Watch's sleep/wake agreement around kappa 0.53, with total sleep time overstated by about 19.6 minutes on average, while the Oura Ring Gen 3 measured around kappa 0.65 in manufacturer-funded studies but only 0.21 to 0.40 in independent ones. That gap is worth keeping in mind before treating a wearable's nightly heart rate graph as a precise medical reading.
A lower heart rate during sleep is generally a normal and expected part of the Dip-and-Recover pattern, not a red flag on its own. Deep NREM (N3) sleep is associated with the body's most restful state, including the release of growth hormone and tissue repair, and it is reasonable for heart rate to fall further during these stages than during lighter sleep or REM. People who are physically fit often show a lower resting and sleeping heart rate than average, which reflects cardiovascular conditioning rather than a problem.
Because there is no single universal cutoff for what counts as "too low" for a given individual, a low nighttime heart rate is best evaluated in context rather than against a fixed number. It is the accompanying symptoms — not the number by itself — that typically matter most for deciding whether it is worth a conversation with a doctor.
A persistently high or elevated heart rate while sleeping runs counter to the expected Dip-and-Recover pattern, and it usually has an identifiable contributor. The most common medical cause is obstructive sleep apnea (OSA), a condition in which breathing is repeatedly interrupted during sleep. OSA is estimated to affect roughly 24 to 33 percent of U.S. adults, and an estimated 80 percent of cases go undiagnosed. Because each breathing interruption and the arousal that ends it place extra demand on the body, OSA is a leading reason someone's heart rate stays elevated overnight instead of following a normal dip.
Substances and habits close to bedtime also play a role. Caffeine has an average half-life of about 5 hours, and even a dose taken as long as 6 hours before bed can measurably disturb sleep — a pattern consistent with an overnight heart rate that runs higher than it otherwise would. Alcohol is often assumed to help sleep, but it is sedating rather than sleep-promoting: it suppresses REM sleep, fragments the second half of the night, and worsens sleep-disordered breathing, which can also contribute to an elevated nighttime heart rate. Stress and anxiety carried into bedtime are commonly reported contributors as well, even without a diagnosed sleep disorder.
When an elevated heart rate while sleeping is tied to OSA, treatment typically starts with addressing the underlying breathing disruption, most often with CPAP therapy. CPAP is effective, but staying consistent with it is a real challenge in practice — only an estimated 30 to 60 percent of users remain adherent to CPAP therapy long-term. If caffeine or alcohol close to bedtime are contributing factors instead, shifting the timing of either is a more straightforward first step than a medical treatment, and it is worth tracking whether nights without them show a more typical Dip-and-Recover pattern.
A sudden spike in heart rate while sleeping, as opposed to a heart rate that stays elevated all night, often lines up with a specific triggering event. In OSA, each pause in breathing and the arousal that follows it can produce a brief spike rather than a steady elevation, which is one reason spikes can recur multiple times a night in someone with untreated sleep apnea. Caffeine or alcohol consumed shortly before bed, a vivid or stressful dream, or a stress response triggered during a lighter sleep stage can also produce a sudden, short-lived jump. An occasional spike is not necessarily concerning, but a pattern of repeated spikes — especially alongside snoring, gasping, or witnessed pauses in breathing — points toward a cause worth investigating rather than ignoring.
Most night-to-night variation in heart rate is not an emergency, but it is worth talking to a doctor if you notice:
Sleep apnea is common and frequently undiagnosed, so these symptoms deserve evaluation rather than guesswork — a doctor can determine whether testing, such as a sleep study, is appropriate.
There is no single figure that applies to everyone, and treating one number as a universal target can be misleading. What your heart rate "should" be while sleeping depends on your age, fitness level, medications, and overall cardiovascular health — factors that vary enough between individuals that a personalized range is more useful than a generic chart. The more reliable signal, for most people, is the Dip-and-Recover pattern described earlier: a heart rate that falls below your typical daytime resting rate as you move into deeper sleep, then rises again toward the lighter stages and waking.
If you are tracking sleeping heart rate with a wearable, treat the trend over weeks as more meaningful than any single night's number, and keep the device's known limitations in mind — consumer sleep trackers have shown only moderate agreement with polysomnography, the clinical gold standard, in independent testing. A calm pre-sleep environment, including reducing stimulation from screens, caffeine, or alcohol in the hours before bed and keeping background sound steady (see best noise machines for sleep for options), can support a more typical overnight pattern. For a personalized target, or if your tracked numbers look consistently unusual, a conversation with a doctor — potentially backed by a clinical sleep study — is the most reliable path, rather than comparing your numbers to a generic online chart.