Heart Rate During Sleep

Physiological Bradycardia

A heart rate of 37-45 beats per minute during sleep is not concerning and does not require treatment, as this represents a normal physiological response due to increased parasympathetic tone during sleep, according to the American College of Cardiology 1, 2
Parasympathetic tone is more dominant than sympathetic tone during rest and sleep, causing significant sinus bradycardia or pauses, which are common during sleep and have been observed across a wide age range, as stated by the American College of Cardiology 1, 2
Young individuals, especially well-conditioned athletes, have dominant parasympathetic tone at rest associated with resting sinus rates that can be well below 40 bpm, as noted by the American College of Cardiology 1
Healthy young individuals, particularly athletes, can have sleeping rates as slow as 30 to 43 beats per minute with sinus pauses producing asystolic intervals as long as 1.6 to 2.8 seconds, according to the American College of Cardiology 3

The American College of Cardiology, American Heart Association, and Heart Rhythm Society guidelines state that in patients with sleep-related sinus bradycardia or transient sinus pauses occurring during sleep, permanent pacing should not be performed unless other indications for pacing are present (Class III: Harm recommendation) 1, 2, 4
Nocturnal bradyarrhythmias are common in both health and disease, with sinus bradycardia being the most common bradyarrhythmia encountered during sleep, as reported in Circulation 4, 5
The American College of Cardiology recommends that asymptomatic bradycardia, even with heart rates below 40 bpm during sleep, does not require treatment 1, 2

If bradycardia occurs with sleep apnea, treatment should be directed at the sleep apnea rather than implanting a pacemaker, as suggested by Circulation and the American College of Cardiology 4, 5, 8
In patients with sleep apnea and sleep-related bradyarrhythmias, frequency of episodes is decreased with continuous positive airway pressure and patients are unlikely to develop symptomatic bradycardia in long-term follow-up, according to the American College of Cardiology and Circulation 5, 8

Overdiagnosis of pathological bradycardia can lead to unnecessary pacemaker implantation, as warned by the American College of Cardiology 1, 2
Failure to recognize sleep apnea as a cause of nocturnal bradycardia may lead to inappropriate treatment, as cautioned by Circulation and the American College of Cardiology 4, 5, 8