Even if you don’t wear a smartwatch or fitness band to measure your heart rate, you can often feel your heart rate fluctuate throughout the day. During your waking hours, the number of heartbeats per minute when you are just sitting still is called the resting heart rate. Most adults have a resting heart rate between 60 and 100 beats per minute.
As soon as you get up and start moving, your heart rate increases. And exercise increases it even more. Even intense emotions – fear, anger, or surprise – can cause your heart rate to increase. But what happens when you go to sleep? The answer varies depending on the phase of sleep: light sleep, deep sleep or REM sleep (Rapid Eye Movement).
How does your heart rate change while you sleep?
“During sleep, the stimulation of your nervous system is reduced and most of your body processes slow down,” says Dr. Lawrence Epstein, Associate Physician for Sleep and Circadian Disorders at Brigham and Women’s Hospital at Harvard.
Within about five minutes of falling asleep, your heart rate gradually slows to its resting rate when you enter what is known as light sleep. Your body temperature will drop and your muscles will relax. People usually sleep lightly for about half the night. In the next phase, deep sleep, your blood pressure drops and your heart rate slows to about 20% to 30% below your resting heart rate.
When you dream, you are entering the phase of sleep known as REM (also known as dream sleep). “Your heart rate can be very different during REM sleep as it reflects the level of activity that is occurring in your dream. If your dream is scary or involves activities like running, your heart rate will increase as if you were awake, ”says Dr. Epstein.
Can you change your resting heart rate?
Regular running or other moderate to vigorous physical activity can lower your resting heart rate. This is because exercise strengthens the heart muscle and allows it to pump a higher volume of blood with each heartbeat. As a result, more oxygen is delivered to the muscles so the heart doesn’t have to beat as often as someone who is less fit.
As you get older, your resting heart rate stays about the same unless you take medicines that slow your heart rate, such as beta blockers or calcium channel blockers.
To determine your resting heart rate, try taking your pulse as you wake up a few days a week for several weeks. Use your index and middle fingers to press lightly on the opposite wrist, just below the fat pad of your thumb. Or, press lightly on the side of your neck, just below your jawbone. Count the number of beats over a 30 second period. Double this number to get your heart rate in beats per minute. (Measuring for just 15 seconds and multiplying by four is pretty accurate too.)
A resting heart rate that is too slow (less than 50 beats per minute) or a heart rate of 100 or more can be a sign of problems and should trigger a call to your doctor.