Countless times each month I treat new patients who have been referred to the sleep clinic due to uncontrolled hypertension or an irregular heart rhythm, as many healthcare providers are becoming aware of the relationship between sleep and cardiovascular health.
Interestingly, 15% to 20% of defibrillator discharges occur during sleep, and it is no secret that myocardial infarctions and cardiac death often occur in the early morning hours. Waking from sleep is a stress on the cardiovascular system, as the sympathetic nervous system is stimulated with the release of catecholamines and BP increases.
The body’s reaction to these changes is different depending on the stage of sleep. During rapid eye movement (REM) sleep there are surges in the sympathetic system, as well as in vagus nerve activity, producing more erratic breathing. In normal individuals these changes do not pose a problem, but in those with poor cardiac health there is an increased risk of myocardial infarction and ischemia.
During non-rapid eye movement (NREM) sleep, BP falls and breathing slows. Getting enough NREM sleep is important, as a decrease in sleep can mean that BP is not dropping appropriately, placing more stress on the heart. Shortened sleep means increased cardiac risk. Remind patients of this when they follow up with you, as more and more Americans try to get by on five to six hours of sleep per night.
Patients who are not getting adequate sleep, or those who alter their bedtime hours throughout the week experience loss of normal circadian rhythms. This loss is also associated with a decrease in cardiovascular health, especially as it relates to hypertension.
Adults who snore loudly have a twofold-increased risk for developing metabolic syndrome, a precursor to cardiac problems, study results have shown. Furthermore, national increases in obesity add to the potential for obstructive sleep apnea (OSA) and other cardiac issues. OSA has been associated with problems including hypertension, cardiac arrhythmias, pulmonary hypertension, congestive heart failure and stroke.
Sleep is a stress test for the heart — knowing a patient’s heart health during sleep can be a valuable tool to assess overall cardiac function. Remind your patients that getting a good night’s rest is cardio protective and remind them not to scrimp on sleep!
Sharon M. O’Brien, MPAS, PA-C, works at Presbyterian Sleep Health in Charlotte, N.C. Her main interest is helping patients understand the importance of sleep hygiene and the impact of sleep on health.