Scientifically Speaking | For better heart health, sleep well

It is necessary to get a full, restful night of sleep and to sustain regular sleep habits over years and decades to maintain good health. Lack of sleep doesn’t just make people irritable or reduce cognitive and physical performance over time. Two recent studies in the Journal of the American Heart Association (JAHA) have now found that poor sleep is linked to poor heart health.

These studies build on what is already known. Those with ideal heart health have a lower risk of cardiovascular disease (and of dying of all causes) than those with poor heart health. Risk factors that lead to poor heart health are lack of exercise, poor diet, smoking, having a high Body Mass Index (usually associated with being overweight), and high blood pressure, high cholesterol, or elevated glucose levels. All of these factors have been well established in medical practice over decades of research. And if you’re like me, you probably hear the need to reduce these risk factors every time you have a health checkup.

But a research paper published in JAHA on October 19, 2022, has found that adjusting for these well-known factors isn’t enough. There’s another one that we need to consider and that’s our sleep habits. Sleep quality predicts heart health and must be a part of any daily regimen. This is the eighth factor that can also lead to poor heart health.

The study followed adult participants of different ethnicities in the United States for years and tracked sleep duration, quality, and variation. Seven to eight hours of sleep every night was considered sufficient. Sleeping for 85% of the time or more after turning off lights at night was considered high-quality. And low variation in getting to sleep, staying asleep, and time slept from one night to the next was considered ideal. Interestingly, all of these measures can be tracked by all of us at home using a standard smartwatch or fitness tracker.

Following on the heels of that study, a second research paper published in JAHA on February 15 has now found that the risk of atherosclerosis – a condition in which plaque builds up in arteries and reduces blood flow– is elevated in poor sleepers. Atherosclerosis can lead to heart attack and stroke. This new study dug deeper into some of the effects of poor sleep and found that inconsistent sleep times and durations are linked to high levels of markers of atherosclerosis.

While this study couldn’t establish that it was sleep that was actually the cause of the rise of these markers, it sets the stage for more detailed analysis. Larger studies in more diverse populations for a longer duration will establish the lifetime risk of heart disease in poor sleepers. The impact of sleep hygiene interventions on heart health can also be studied in future clinical trials.

With that said, the broader conclusions of these two research studies make sense. Proper sleep time and schedules are important for health in general, and heart health in particular.

The circadian rhythm, which is the diurnal cycle of the body clock, regulates sleep. But it is also tied to nearly every aspect of human health. For example, for years now, we’ve known that heart attacks are more likely to occur in the morning than at any other time of day. And even normal blood pressure, heart rate, and blood vessel function vary through the day.

These two studies accentuate the need for me to sleep better too. I used to be a sound sleeper who routinely got in seven hours of restful sleep through my college and postgraduate years. Years of travel across time zones, guzzling caffeinated beverages at night, late-night television, typing and scrolling on devices, parenting a child, and the trials and tribulations of the middle years of life have ruined my own sleep hygiene.

Towards improving my own sleep hygiene I could certainly eat at more regular times, cut down on blue light in evenings, and exercise and meditate more often. These easy interventions are demonstrated to help regulate sleep cycles. Sticking to a regular sleep schedule would also help.

How about you? Are you a poor sleeper or a sound one? Your heart wants to know.

Anirban Mahapatra is a scientist by training and the author of a book on COVID-19

The views expressed are personal

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