It is recommended you sleep seven to eight hours per night. Diverging from the recommended duration could be bad for you, but too much sleep is actually worse than too little, researchers find.
The researchers conclude that “longer duration of sleep may be more associated with adverse outcomes compared with shorter sleep durations.”
“We observed that divergence from the recommended 7 to 8 hours of sleep was significantly associated with a moderate increase in mortality and incident [cardiovascular diseases],” they reported in the Journal of the American Heart Association.
They pooled data from 74 studies related to sleep duration, covering more than 3.3 million people. Among the participants were reported some 242,240 deaths among 2.5 million participants who reported death events.
Sleeping for 9 hours, for example, carried a 14 percent higher risk of death, while 10-hour sleeps carried a 30 percent higher risk, they reported.
They also found no “significant different” for sleep periods less than seven hours being linked to cardiovascular diseases.
Cardiovascular diseases generally affect the heart and blood vessels, and typically include heart failure, heart attack, stroke. Some of them may overlap due to a common underlying condition.
Exactly how sleep and cardiovascular diseases are associated is not fully understood.
Short sleep duration has been shown to increase levels of leptin, which balances how much energy you spend by inhibiting hunger) and ghrelin, which tells your body when to become hungry and search for food.
Increased levels of both hormones leads to increased appetite—you consume more calories, burn less energy and that helps along the development of obesity.
The hormone cortisol regulates many things from metabolism to immune response. Reduced sleep pushes up cortisol and any alteration may increase risk of cardiovascular disease.
The risk of cardiovascular diseases increase with long sleep period especially when other factors associated with cardiovascular diseases are prevalent, leading to fatigue, such as chronic inflammatory disorders and anaemia.
Depressive symptoms, low socioeconomic status, unemployment, and low physical activity are also associated with long sleep duration, the researchers say.
