Sleep plays an important role in overall health. Not getting enough sleep, or not getting enough good-quality sleep, is associated with a higher risk of many negative health outcomes. The following are just some of the outcomes linked to poor sleep:
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Coronary heart disease. Sleeping less than 7 hours per night is associated with a higher risk of coronary heart disease (CHD) and an elevated risk of cardiovascular disease (CVD) mortality.[1][2] Additionally, a genetic study found that a short sleep duration (6 or fewer hours per night) appeared causally related to a higher risk of CHD, high blood pressure, and heart attack.[3]
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Obesity: Getting less sleep is associated with a higher risk of obesity.[4][5] Consistent with this association, restricting sleep to just 4 hours per night has been shown to increase hunger and calorie intake and lead to weight gain (sometimes in as little as 5 days).[6][7] Conversely, increasing sleep time from 5.9 to 7.1 hours per night in one clinical trial led to a reduction in caloric intake and a loss of body fat after 2 weeks.[8]
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Alzheimer’s disease: Poor quality sleep and sleep problems are associated with a higher risk of Alzheimer’s disease, and a short sleep duration is linked to a faster rate of cognitive decline.[9][10] This could be related to the glymphatic system, a biological drainage system active during sleep that seems to clear the brain of beta amyloid, a protein linked to Alzheimer’s disease.[11][12]
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Type 2 diabetes: A meta-analysis of roughly one million people found that a short sleep duration(6 or fewer hours per night) was associated with an increase in the risk of type 2 diabetes.[13] Additionally, a genetic study found that insomnia increased the risk of type 2 diabetes, suggesting a causal association between sleep problems and diabetes.[14]
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Bone fracture: Sleep disturbances, insomnia, and a short sleep duration (less than 7 hours per night) are associated with a higher risk of breaking a bone, possibly by increasing the tendency to fall.[15][16][17] A relationship between poor sleep, bone fractures, and low bone mineral density has also been observed in genetic studies.[16][18]
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Depression: A short sleep duration (7 or fewer hours per night) is associated with a greater risk of depression. Having insomnia is also associated with a higher risk of developing depression[19] and treating insomnia has been shown to improve symptoms of depression.[20][21][22]
Health outcomes linked to poor sleep
