Sleep duration and mortality
Affect of sleep duration on coronary heart disease, stroke, and total cardiovascular disease
Sleep duration and coronary artery calcification
Sleep duration and hypertension
Effect of obstructive sleep apnoea on the cardiovascular system
Conclusion 
References 
Further reading 

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We all know about 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 is the incidences of heart disorders.

Sleep duration and mortality

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.

Affect of sleep duration on coronary heart disease, stroke, and total cardiovascular disease

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, a total of 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 total cardiovascular disease.

Sleep duration and coronary artery calcification

Coronary artery calcification is known to be a predictor of future incidences of coronary heart disease. Based on this, a 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 decreases their odds of calcification by 33%. When modeled, this effect of one extra hour of sleep on the reduced incidence of calcification is similar to a decrease in 16.5 mm Hg of systolic blood pressure.

Sleep duration and hypertension

It has been hypothesized that there is a link between increased incidences of hypertension and decreased average sleep duration. An important study tested this 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 who got more than 9 hours of sleep per night than subjects averaging 7-8 hours of sleep per night.

Habitually sleeping for a shorter duration could cause increased 24-hour blood pressure, heart rate, and sympathetic nervous system activity. Short sleep duration can influence hypertension in several ways, such as disturbing the circadian rhythm and autonomic balance and hampering a healthy lifestyle. 

Effect of obstructive sleep apnoea on the cardiovascular system

Obstructive sleep apnoea is a common disorder in which repetitive episodes of apnoeas throughout the night due to upper airway collapse can lead to cardiovascular disorders. Obstructive sleep apnoea in middle-aged patients, free of other cardiological disorders, plays a significant role in early signs of atherosclerosis. Obstructive sleep apnoea strongly correlates with functional and structural vascular abnormalities.

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.

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 possibly reduce the risk of acquiring heart diseases or even mortality.

References

• Nagai, M., Hoshide, S., & Kario, K. (2010). Sleep duration as a risk factor for cardiovascular disease- a review of the recent literature. Current cardiology reviews, 6(1), 54–61. https://doi.org/10.2174/157340310790231635
• Cappuccio, F. P., et al. (2011). Sleep duration predicts cardiovascular outcomes: a systematic review and meta-analysis of prospective studies. European heart journal, 32(12), 1484–1492. https://doi.org/10.1093/eurheartj/ehr007
• King C.R., et al. (2008). Short Sleep Duration and Incident Coronary Artery Calcification. JAMA. https://jamanetwork.com/journals/jama/fullarticle/183124
• Gangwisch, J.E., et al. (2006). Short Sleep Duration as a Risk Factor for Hypertension. Hypertension, 47, pp 833–839. https://doi.org/10.1161/01.HYP.0000217362.34748.e0
• Drager, L. F., et al. (2005). Early signs of atherosclerosis in obstructive sleep apnea. American journal of respiratory and critical care medicine, 172(5), 613–618. https://doi.org/10.1164/rccm.200503-340OC
• Bradley, T. D., & Floras, J. S. (2009). Obstructive sleep apnoea and its cardiovascular consequences. Lancet (London, England), 373(9657), 82–93. https://doi.org/10.1016/S0140-6736(08)61622-0

Further Reading

• All Sleep Content
• What is Sleep?
• Types of Sleep Disorders
• How Can Mindfulness Meditation Improve Sleep?
• Promoting Sounder Sleep in Older Adults

Written by

Akanksha Singh

Akanksha has studied Dental Surgery from Bangalore, India. During her undergraduate degree, she was awarded the Best Student in Academics in 2016 and obtained University ranks in Microbiology and Pathology, and Conservative Dentistry.