Seven hours is perfect sleep length for health, according to a recent study.
People who sleep more or fewer than seven hours a day, including naps, are increasing their risk for cardiovascular disease, the leading cause of death in the United States, say researchers at West Virginia University School of Medicine.
They published their findings in the August 1, 2010 issue of the journal “Sleep.”
The researchers followed more than 30,000 adults, all of whom were healthy at the start of the study. They found that short and long sleep duration were associated with increased heart disease risk even when they controlled for age, sex, race, ethnicity, smoking, alcohol intake, and other risk factors.
Adults who slept less than five hours a day (including naps) were more than twice as likely to develop heart disease. Those who slept more than nine hours or longer a day were one and a half times more likely to develop heart disease.
The authors of the WVU study were unable to determine the causal relationship between how long a person sleeps and cardiovascular disease.
But they pointed out that sleep duration affects endocrine and metabolic functions, and sleep deprivation can lead to impaired glucose tolerance, reduced insulin sensitivity and elevated blood pressure, all of which increase the risk of hardening the arteries.
The American Academy of Sleep Medicine recommends that most adults get about seven to eight hours of sleep each night.