Your sleeping heart rate is the number of times your heart beats per minute while you’re asleep, and it’s typically 20% to 30% lower than your resting heart rate during the day. For most adults with a daytime resting rate of 60 to 100 bpm, that puts the sleeping range roughly between 40 and 80 bpm. This natural dip is one of the most important things your cardiovascular system does each night, giving your heart and blood vessels time to recover.
Why Your Heart Rate Drops During Sleep
When you fall asleep, your nervous system shifts gears. The branch responsible for “rest and digest” functions takes over, lowering your heart rate and blood pressure while reducing resistance in your blood vessels. This collectively supports cardiac recovery, essentially giving your heart a lighter workload for several hours straight.
This drop follows your body’s internal circadian clock. Heart rate and blood pressure reach their lowest point during the middle of the night, then gradually climb in the early morning hours before you wake. The pattern is consistent enough that cardiologists consider it a sign of cardiovascular health. People whose heart rate fails to dip adequately at night, sometimes called “non-dippers,” tend to have higher risks for heart problems over time.
How Heart Rate Changes Across Sleep Stages
Your heart doesn’t beat at one steady pace all night. It fluctuates with each sleep stage, and those fluctuations can be surprisingly large.
During non-REM sleep, which includes the lighter stages and deep sleep, your heart rate gradually decreases. It hits its lowest values during deep sleep (stage N3), sometimes called “quiet sleep.” Blood pressure and nervous system activity follow the same downward trend. This is the most restorative phase for your cardiovascular system.
When you shift into REM sleep, the stage associated with vivid dreaming, the pattern reverses. Your heart rate increases, sometimes rising to levels comparable to being awake. Blood pressure spikes, and your nervous system ramps up activity. Because you cycle through REM and non-REM stages multiple times each night (with REM periods getting longer toward morning), your heart rate follows a wave-like pattern: dropping, rising, dropping, rising.
If you wear a fitness tracker to bed and notice your heart rate graph looks like rolling hills rather than a flat line, that’s completely normal. It reflects healthy cycling between sleep stages.
Normal Ranges by Age
Sleeping heart rate norms vary significantly with age, largely because resting heart rates are much higher in young children. Here are typical resting rates while awake (sleeping values will be lower):
- Newborns (birth to 4 weeks): 100 to 205 bpm
- Infants (4 weeks to 1 year): 100 to 180 bpm
- Toddlers (1 to 3 years): 98 to 140 bpm
- Preschool age (3 to 5 years): 80 to 120 bpm
- School age (5 to 12 years): 75 to 118 bpm
- Adolescents (13 to 17 years): 60 to 100 bpm
- Adults (18 and older): 60 to 100 bpm
Since sleep typically lowers heart rate by 20% to 30%, an adult with a daytime resting rate of 70 bpm might see nighttime values around 49 to 56 bpm. For children, the same percentage drop applies to their higher baseline, so a toddler’s sleeping heart rate will still be well above an adult’s.
Athletes and Very Low Sleeping Rates
Endurance athletes and highly fit individuals often have resting heart rates in the 40s or even 30s while awake, because their hearts pump more blood per beat and don’t need to work as hard. During sleep, those numbers can drop into the low 30s. This is generally a sign of cardiovascular efficiency, not a problem.
If you’re physically active and your wearable shows a sleeping heart rate in the mid-30s but you feel fine during the day (no dizziness, fainting, or unusual fatigue), there’s usually nothing to worry about. The concern starts when a very low sleeping heart rate pairs with symptoms like lightheadedness or chronic exhaustion, which could signal an electrical issue in the heart rather than fitness.
What a High Sleeping Heart Rate Can Mean
A sleeping heart rate that stays elevated, or one that suddenly trends upward over days or weeks, can reflect several things. Some are temporary and harmless, others worth paying attention to.
Common everyday causes include alcohol consumption (even moderate drinking raises overnight heart rate), caffeine too close to bedtime, stress, dehydration, and illness. A fever can push your sleeping heart rate 10 or more bpm above your baseline, and it often returns to normal once you recover.
Medical conditions that can chronically elevate your nighttime heart rate include thyroid disorders (particularly an overactive thyroid), anemia, heart rhythm problems like atrial fibrillation, low blood sugar, and electrolyte imbalances. Sleep apnea is another major contributor. When breathing repeatedly stops and restarts during the night, the body responds with surges in heart rate and blood pressure that prevent the normal overnight dip.
Tracking Your Sleeping Heart Rate
Most people checking their sleeping heart rate are using a wrist-worn fitness tracker or smartwatch. These devices use optical sensors that shine light through your skin and measure blood flow changes to estimate heart rate. They’re generally reliable for showing trends over time, even if any single reading may be off by a few beats compared to a medical-grade monitor.
What matters most isn’t one night’s number but your pattern over weeks and months. Look for your average sleeping heart rate and note whether it stays stable, gradually decreases (often a sign of improving fitness), or suddenly climbs. A sustained increase of 5 or more bpm above your personal baseline, lasting more than a few days without an obvious cause like illness or stress, is worth noting.
Your lowest heart rate of the night, which typically occurs during deep sleep in the first half of the night, is often the most useful single number to track. Many wearables report this automatically. For most healthy adults, that number falls somewhere between 40 and 60 bpm.