Is a lower heart rate during sleep abnormal?

Something that was said at my wife's recent doctor visit caused her cardiologist to want me to make an appointment. This morning the heart doc said my heart rate got too low when I wore a monitor overnight in January, and again in March when I had my sleep study. So now I get another nuclear stress test and have to wear a heart monitor for 21 days.

My sleep study says:
Mean heart rate during sleep = 55.4 bps
Highest heart rate during sleep = 75 bpm
Highest heart rate during recording = 87 bpm
Lowest heart rate during recording = 53 bpm

Is this abnormal?

Do you do any kind of regular aerobic exercise? That can cause a bradycardia. My resting rate is commonly in the 50's and drops lower than that during sleep.

Certain medications, particularly beta blockers used for high blood pressure, can have the same effect.

frh wrote:Something that was said at my wife's recent doctor visit caused her cardiologist to want me to make an appointment. This morning the heart doc said my heart rate got too low when I wore a monitor overnight in January, and again in March when I had my sleep study. So now I get another nuclear stress test and have to wear a heart monitor for 21 days.

My sleep study says:
Mean heart rate during sleep = 55.4 bps
Highest heart rate during sleep = 75 bpm
Highest heart rate during recording = 87 bpm
Lowest heart rate during recording = 53 bpm

Is this abnormal?

It is not abnormally low for a man: