We all know the importance of getting a good night’s sleep, but can it affect our heart health?
People in western countries sleep for about 6.8 hours per night. A century ago, this duration was at 8.3 hours. Sleep deprivation is getting more prevalent in developed societies, and so are the incidences of heart disorders.
A study collected mortality data from 6,928 adults over nine years. It showed that adults getting 7-8 hours of sleep per night had a lower mortality rate from ischemic heart disease, cancer, and stroke. Men getting less than 6 hours or more than 9 hours of sleep had a 1.7 times higher death rate. This suggests that there is a link between sleep duration and mortality.
A review was conducted of 15 studies that assessed the impact of sleep duration on cardiovascular events. This review included 474,684 male and female participants, and follow-up was done for 6.9 to 25 years. During this period, 16,067 events occurred (4,169 for coronary heart disease, 3,478 for stroke, and 8,420 for total cardiovascular disease). This study aimed to determine a relationship between either short or long sleep duration and coronary heart disease, stroke, and total cardiovascular disease.
In the analysis, participants getting less than 5-6 hours of sleep had an increased risk of mortality due to coronary heart disease or developing the disease. This increased risk is about 48% for short sleepers and 38% for people getting more than 8-9 hours of sleep.
Regarding the relationship between stroke and sleep duration, it was found that short sleepers (<5-6 hours) have an increased 15% risk of stroke. On average, individuals sleeping for more than 8-9 hours per night had an increased stroke risk of 65%.
Furthermore, the link between total cardiovascular disease and sleep duration was also assessed. However, no significant relationship was found between short sleep duration and total cardiovascular disease. But long sleepers are more likely to acquire heart disease.
Another study at the University of Chicago looked for an association between sleep duration and coronary artery calcification. This study had 495 participants, and the follow-up was done for five years.
They found a potent relationship between decreased sleep duration and increased incidence of coronary artery calcification. Additionally, they found that an individual increasing their sleep duration by one more hour reduces their odds of calcification by 33%.
A critical study also tested the link between increased incidences of hypertension and decreased average sleep duration by conducting longitudinal analyses of a sample size of 4,810 subjects. The study revealed that a higher percentage of younger subjects, who got less than 7 hours of sleep than those who slept for 7-8 hours per night, were diagnosed with hypertension in the follow-up period of 8-10 years. With older subjects, a higher percentage got diagnosed with hypertension and got more than 9 hours of sleep per night than subjects averaging 7-8 hours per night.
Some epidemiological studies have found a strong relationship between Obstructive sleep apnoea and stroke, heart failure, arrhythmias, and hypertension. An individual with Obstructive sleep apnoea has a higher risk of acquiring cardiovascular diseases.
In conclusion, Individuals who sleep less than 6-7 hours or more than 9 hours per night have a higher risk of developing various heart diseases and are even prone to cardiovascular mortality. Sleep disorders such as obstructive sleep apnoea can also lead to cardiovascular diseases.
As proper sleep is critical for heart health, interventions focusing on achieving the ideal sleep duration and quality can reduce the risk of acquiring heart diseases or even mortality.
Parvathy Sukumaran 
