By Julie Corliss, Executive Editor, Harvard Heart Letter
Even if you don't wear a smartwatch or activity tracker to
monitor your heart rate, you can often feel your heart rate fluctuating
throughout the day. During your waking hours, the number of heartbeats per
minute when you are sitting still is called your resting heart rate. Most
adults have a resting heart rate between 60 and 100 beats per minute.
As soon as you get up and move, your heart rate increases,
and the workout speeds it up even more. Even strong emotions fear, anger, or
surprise can make your heart rate skyrocket. But what happens when you go to
sleep? The answer differs depending on the sleep stage: light sleep, deep sleep
or REM (rapid eye movement) sleep.
How does your heart rate change while you sleep?
"During sleep, stimulation of your nervous system is
reduced, and most processes in your body slow down," says Dr Lawrence
Epstein, Associate Physician in the Division of Sleep and Circadian Disorders
at Brigham and Women's Hospital affiliated with Harvard.
Within about five minutes of falling asleep, your heart rate
will gradually slow down to the resting speed as you enter what is known as
light sleep. Your body temperature drops, and your muscles relax. People
typically spend about half of the night in a light sleep. But during the next
phase, deep sleep, your blood pressure drops, and your heart rate slow to
20-30% below your resting heart rate. When you dream, you enter the sleep phase
known as REM (also known as dream sleep). "Your heart rate can vary quite
a bit during REM sleep as it reflects the level of activity that occurs during
your sleep. 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. That's because exercise strengthens
the heart muscle, allowing it to pump a larger blood volume with each
heartbeat. This allows more oxygen to flow to the muscles, so the heart doesn't
have to beat as often as it does in someone less fit.
As you age, your resting heart rate stays about the same
unless you're taking medications that slow your heart rate, such as B.
beta-blockers or calcium channel blockers.
To determine your resting heart rate, measure your heart
rate after waking 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 gently press on the side of his neck, just below his jaw.
Count the number of beats in 30 seconds. Double this number to get your heart
rate in beats per minute. (Just measuring for 15 seconds and multiplying by
four is pretty accurate too.)
A resting heart rate that's too low (less than 50 beats per
minute) or a heart rate of 100 or more can be a sign of trouble, and you should
call your doctor.
