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Researchers have found a link between sleeping for more than eight hours a night and chances of having heart disease or dying prematurely. Cardiovascular diseases affect the heart and blood vessels, researchers examined the cardiovascular risk associated with each hour below seven hours and above eight hours of sleep per night.
Researchers pooled together 74 existing studies from 1970 to 2017, covering millions of participants. The existing studies used population registries, death certificates, questionnaires, interviews and medical records to access information about cardiovascular disease and health. To gain information on sleep duration, they used questionnaires or interviews.
They found that getting more than eight hours of sleep was associated with an increased risk of cardiovascular disease-a 17% increase for nine hours and a- 23% increase for ten hours of sleep. They also found a link between longer sleep times and an increased risk of premature death-a 23% increase for nine hours, a 52% increase for ten hours and a 66% increase for 11 hours of sleep.
Sleep durations of less than seven hours were also associated with strokes, although to a lesser extent than longer sleep durations. Five hours of sleep was associated with a 29% increased risk of strokes, compared to a 41% increase with ten hours of sleep. Poor sleep quality wasn’t associated with increase in premature death, but it was associated with a 44% increased risk of coronary heart disease.
Sleeping longer than seven to eight hours a night may be associated with a moderate degree of harm compared to sleeping for shorter than recommended. Sleep duration and quality may increase the risk of cardiovascular disease.
Health challenges that can lead to increased subjective sleep duration or reduced sleep quality are depression, obstructive sleep apnoea, anaemia, inflammatory disorders and other sleep disorders. These health challenges may be the underlying mechanisms leading to an increased risk of cardiovascular disease and sleep duration.
Studies conducted in controlled experimental conditions show that not getting enough sleep affects physical and psychological functioning and can contribute to the development of chronic health issues such as type 2 diabetes.