Heart Rate In Rem Sleep: What's Normal?

Sleep is a restorative process, so it makes sense that your heart rate declines during sleep. A normal resting heart rate for adults ranges from 60 to 100 beats per minute, though this can vary depending on factors such as age, weight, and fitness level. Generally, a sleeping heart rate should be at the low end of normal, even for people who aren't physically fit. During sleep, you can expect your heart rate to drop to the low end of your normal range. For example, if your resting heart rate is between 70 and 85 beats per minute, your sleeping heart rate might be between 70 and 75 beats per minute, or even slower.

There is one exception to this: it's normal for your heart rate to increase during REM sleep. During this sleep stage, your brain becomes highly active, and your heart rate may follow suit. However, it still shouldn't surpass your normal daytime heart rate.

Heart rate during REM sleep in cats

Rapid Eye Movement (REM) sleep is characterised by profound autonomic nervous system activation, which causes heart rate surges in humans and canines. Research has shown that this phenomenon also occurs in cats.

Heart Rate Surges During REM Sleep in Cats

One study found that heart rate surges during REM sleep in cats are associated with theta rhythm and PGO activity. The study recorded cortical and hippocampal electroencephalogram, electromyogram, electrooculogram, pontogeniculooccipital (PGO) waves, subcutaneous electrocardiogram, and respiration. Results showed that bouts of sinus tachycardia lasting over 3.5 seconds achieved a rate of 210 beats per minute and were predominantly present during REM sleep.

Heart Rate During REM Sleep

During REM sleep, the heart rate may speed up to a level similar to when the cat is awake. This is because REM sleep is often marked by periods of higher activity, which is considered normal.

Factors Affecting Heart Rate During Sleep

Several factors can influence heart rate during sleep, including stress and anxiety, sleep behaviours, and pregnancy. High heart rates during sleep are connected with taking longer to fall asleep, experiencing lower sleep quality, and an increased risk of cardiovascular disease.

Measuring Heart Rate During Sleep

To measure heart rate during sleep, individuals can use wearable devices such as smartwatches or smart sensors that integrate into the bed.

Heart rate variability during sleep

Heart rate variability (HRV) refers to the variation in the amount of time between heartbeats. When you're in fight-or-flight mode and your heart is racing, there is little time between heartbeats (low HRV). On the other hand, when you're relaxed, your heart beats slower and there's more time between heartbeats (high HRV).

The higher your HRV, the better, especially during sleep. A high HRV means your body is adaptable and ready for any changes. Your HRV is a direct indication of how much stress your body is under at a given time, which is why you want to see a high HRV during sleep.

If your sleep tracker data shows low HRV, your body is in overdrive during sleep for some reason. Studies show that low sleep HRVs may indicate sleep disorders, so if yours is consistently low, consider the factors that may affect it: stress levels, bedtime routine, and sleep environment. If you suspect a medication or medical condition is the culprit, talk to your doctor.

During sleep, it is normal for a person's heart rate to slow down below the range for a typical resting heart rate. Between 40 and 50 beats per minute is considered an average sleeping heart rate for adults, though this can vary depending on multiple factors.

In general, heart rate is slower during sleep than when a person is awake. However, heart rate also changes as a sleeper cycles through the different stages of sleep. In the first stages of light sleep, heart rate begins to slow. During deep sleep, the heart rate reaches its lowest levels. In rapid eye movement (REM) sleep, heart rate may speed up to a heart rate similar to when you are awake.

How to measure your sleeping heart rate

Measuring your heart rate during sleep can help you detect any irregularities and keep track of your overall health and sleep quality. Here are some ways to measure your sleeping heart rate:

Smartwatches and Wearable Devices

Smartwatches and fitness bands are a convenient way to monitor your heart rate while you sleep. These devices can provide real-time data and allow you to track your heart rate trends over time.

In-Lab or At-Home Sleep Study

If you suspect you may have a sleep disorder, your doctor may recommend an in-lab or at-home sleep study. These studies use professional equipment to accurately measure your heart rate and other sleep parameters.

Heart Rate Monitors

Heart rate monitors typically consist of a wireless sensor on a strap that you wear around your chest. The sensor detects your pulse and sends the data to a receiver, such as a wristwatch, which displays your heart rate. Some heart rate monitors have sensors on the back of the wristwatch itself, which measure your heart rate through your skin.

Smartphone Apps

There are also smartphone apps available that can measure your heart rate. For these apps, you usually place your finger on the phone's camera lens, which detects the subtle colour changes in your finger that occur with each heartbeat.

Manual Measurement

You can also measure your heart rate manually by taking your pulse. Use your index and middle fingers to gently press on the inside of your wrist or the side of your neck, just below your jawbone. Count your heartbeats for 15 or 30 seconds and multiply that number by four to get your heart rate in beats per minute. It's best to do this first thing in the morning, after you've been resting.

It's important to note that your heart rate can vary depending on your sleep stage. It tends to be slower during non-rapid eye movement (NREM) sleep and may speed up during REM sleep, when dreaming occurs. Additionally, factors such as stress, anxiety, sleep behaviours, and physical activity can influence your sleeping heart rate.

What is a good heart rate when sleeping?

A good heart rate when sleeping is typically between 40 and 50 beats per minute (bpm) for adults, although this can vary depending on multiple factors. For example, physically fit people may have resting heart rates as low as 30 bpm, and children tend to have higher heart rates than adults.

Your heart rate isn't just affected by sleep but also by your sleep cycle. During the first stages of light sleep, your heart rate begins to slow down. It reaches its lowest levels during deep sleep. In rapid eye movement (REM) sleep, your heart rate may speed up to a level similar to when you are awake, especially if you are having an intense dream.

Your sleeping heart rate is also affected by factors such as stress, anxiety, sleep behaviours, and underlying medical conditions.

If you want to measure your sleeping heart rate, you can use a smartwatch, fitness tracker, or a health app on your phone.

How does your heart rate change while you sleep?

Your heart rate changes as you cycle through the different stages of sleep. In the first stages of light sleep, your heart rate begins to slow down. During deep sleep, your heart rate reaches its lowest levels. In rapid eye movement (REM) sleep, your heart rate may speed up to a rate similar to when you are awake.

During light sleep, your heart rate gradually slows to its resting rate. Your body temperature drops and your muscles relax. People typically spend about half the night in light sleep.

During deep sleep, your blood pressure falls and your heart rate slows to about 20% to 30% below your resting heart rate.

During REM sleep, your heart rate can vary quite a bit and reflects the activity level occurring in your dream. If you are having a scary dream or one that involves activity such as running, your heart rate rises as if you were awake.

On average, a normal resting heart rate is between 60 and 100 beats per minute. However, a normal heart rate during sleep drops to between 40 and 50 beats per minute.

Your heart rate is slower during sleep than when you are awake. However, it is important to note that your heart rate will be relatively low while you are asleep. If your heart rate does not decline during sleep or speeds up higher than your daytime resting heart rate, it could indicate a medical or psychological condition such as anxiety or atrial fibrillation.

There is one exception: it is normal for your heart rate to increase during REM sleep. During this sleep stage, your brain becomes highly active, and your heart rate may follow suit. However, your heart rate still shouldn't soar past your normal daytime heart rate.

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