When the major risk factors for cardiovascular disease are listed, sleep deprivation is not usually among them. However, a growing body of research suggests a link between sleep duration and cardiovascular disease. While this pairing seems unlikely, it adds urgency to having timely and restful sleep to minimize the risk of danger to the heart.
The Dangers of Cardiovascular Disease
Cardiovascular disease, disease of the heart, causes over 787,000 deaths in the United States each year. There are many different kinds of heart disease, each with varying levels of mortality and treatability:
- Coronary heart disease
- Heart failure
- Heart attack
The Importance of a Good Night’s Sleep
The CDC recommends that people 18 years or older should get 7 or more hours of sleep per night. The quality of sleep is also critical. Restless sleep or sleep that does not leave a person feeling rested does not have the health benefits that a night of restful sleep does, and the quality of sleep a person gets appears to contribute to cardiovascular disease risk.
There are many remedies for sleep that is not restful. These are dependent on the underlying cause of restless sleep, i.e. insomnia, sleep apnea, etc. Speak with your primary physician about how you can have more restful sleep and minimize your risk of cardiovascular disease.
Sleep Duration and Cardiovascular Disease—An Unlikely Pairing
In this article, we will focus on a meta-analysis published in the Journal of the American Heart Association in 2018. The analysis pooled the research of 74 studies representing over 3 million participants. The conclusion was a definite relationship between sleep duration and cardiovascular disease.
Is Less More?
Despite the well-known adverse effects of getting insufficient sleep, no significant difference in cardiovascular risk levels were observed for sleep duration less than 7 hours. This was true for markers of both stroke and cardiovascular disease mortality.
That being said, short sleep duration has a known relationship with increased levels of ghrelin and leptin, and these lead to increased appetite and caloric intake in addition to reduced energy expenditure, facilitating the development of obesity and impaired glycemic control. Reduced sleep is also associated with low-grade inflammation, which may be associated with cancer and cardiovascular disease.
Don’t Overdo It
If the relationship between sleep duration and cardiovascular disease was tenuous at fewer than 8 hours of sleep, it is definitive for more than 8 hours. Despite the easy assumption that more sleep equates to better health, duration of sleep greater than 8 hours was associated with higher risk of cardiovascular event. Risk of mortality from stroke and other cardiovascular disease increased to moderate past the 8-hour mark, and the risk only rose with each hour:
- 9 hours of sleep – 14% increased risk
- 10 hours of sleep – 30% increased risk
- 11 hours of sleep – 47% increased risk
From the data, we can see that “the greater the divergence from the recommended durations of sleep, the greater the association for cardiovascular harm and mortality.” Though the bell-curve remains, this is more true of longer sleep duration than of shorter duration.
While higher risk of mortality due to cardiovascular event should be impetus enough for getting 40 winks, it should also be noted that researchers found that non-cardiovascular factors such as low physical activity, unemployment, low socioeconomic status, and depression were also associated with long sleep duration.
The research shows a clear correlation between sleep duration and cardiovascular disease. It also indicates that the quality of sleep is fundamental to low risk levels. While “poor sleep quality” is a subjective metric, factors such as waking up unrefreshed were measured and discovered to be markers of elevated cardiovascular risk.
Specifically, a significant increase in coronary heart disease was observed. Abnormal sleep increased the risk of coronary heart disease by 47%. Incidence and mortality markers of other cardiovascular diseases were not observed.
The meta‐analysis, systematic review, and spline analysis of the cohort studies in question revealed a bell curve relationship between sleep duration and cardiovascular disease, both of incidence and mortality. Poor sleep quality was also discovered to increase risk of coronary heart disease.
The CDC’s recommendation of 7 or more hours of sleep per night is too broad a stroke to limit the risk of cardiovascular disease. A recommendation which better incorporates the relationship between sleep duration and cardiovascular disease is between 7 and 8 hours of restful sleep each night.