Eight hours of sleep may do you good, but five hours or less could actually do you harm, or so suggests a new study. The PLOS Medicine study of British civil service workers used self-reported sleep duration measurements collected six times between 1985 and 2016; that data was bucketed into three looks at each person: at ages 50, 60, and 70. Among the 7,217 participants who had no chronic diseases at age 50, some 62% developed a first chronic disease over the course of the study, and about half of those people eventually developed at least two chronic diseases; 787 people died.
The researchers found that those who logged five hours or less of sleep when they were 50 had a 30% greater risk of multimorbidity (meaning two or more chronic conditions) over time than those who slept seven hours. The risk increased to 32% at 60 and 40% at 70, reports CNN, which details some of the diseases for which there was elevated risk (diabetes, cancer, coronary heart disease, and liver disease among them). "The big question is why do some people sleep less," Surrey Sleep Research Centre chief Derk-Jan Dijk tells the BBC. "What is causing it and is there anything we can do about it? Sleep is a modifiable lifestyle factor to a certain extent."
Lead author Dr. Severine Sabia said in a press release that "multimorbidity is on the rise in high-income countries and more than half of older adults now have at least two chronic diseases. This is proving to be a major challenge for public health, as multimorbidity is associated with high health-care service use, hospitalizations, and disability." The researchers note that their findings "support the promotion of good sleep hygiene." It's worth noting a few caveats related to the study: Most participants were white, and only about a third were female. (More discoveries stories.)
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