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A large new study published provides evidence that people 50 and older who sleep five hours or less at night have a greater risk of developing multiple chronic diseases as they age compared with peers who get a longer night’s rest.
The study, published Tuesday in the journal PLOS Medicine, took a closer look at a group of nearly 8,000 civil servants in the United Kingdom who had no chronic disease at age 50. Scientists asked the participants to report on how much sleep they got during clinic examinations every four to five years for the next 25 years.
For those whose sleep was tracked at age 50, people who slept five hours or less a night faced a 30% higher risk that they would develop multiple chronic diseases over time than those who slept at least seven hours a night. At 60, it was a 32% increased risk, and at 70, it was a 40% greater risk.
Diseases for which there was a higher risk included diabetes, cancer, coronary heart disease, stroke, heart failure, chronic obstructive pulmonary disease, chronic kidney disease, liver disease, depression, dementia, mental disorders, Parkinson’s and arthritis.
Other research has shown that adults who do not get enough sleep – about seven to nine hours a night – have a greater chance of developing chronic diseases that also include obesity and high blood pressure, according to the US Centers for Disease Control and Prevention.
Unlike other studies, the new one did not find that those who slept longer than nine hours had health problems, but few people in the study slept that much, and that may have affected the results.
The study has some additional limitations. Most of the subjects were White men; only about a third were women. The researchers say the civil servants also tend to be a little healthier than the general population. And the study relied on self-reported data, which is considered less reliable than if people were in a sleep study in which scientists could directly observe how the person was sleeping.
“Short sleep duration in midlife and old age is associated with higher risk of onset of chronic disease and multimorbidity,” the study concluded. “These findings support the promotion of good sleep hygiene on both primary and secondary prevention by targeting behavioral and environmental conditions that affect sleep duration and quality.”
Sharon Cobb, who has worked on sleep research and was not involved with the new study, said it’s important because it provides more evidence that sleep and chronic conditions are related.
“I think for a long time, we’ve stressed that you need your sleep. But now we’re starting to really push forward. There’s more literature coming out that sleep can affect more than just mental health. It’s also affecting more comorbidities,” said Cobb, who is the director of prelicensure nursing programs and an associate professor at the Mervyn M. Dymally School of Nursing at Charles R. Drew University of Medicine and Science in Los Angeles.
Cobb points out that duration is important with sleep, but so is quality – a factor this study did not capture. The study also doesn’t explain what may be causing the chronic conditions among the people who slept five hours or less.
Other research has shown that sleep is a restorative process that, among other things, produces and regulates hormones in the body, explains Adam Knowlden, an associate professor of health science at the University of Alabama, who was not involved in the new research but is working on a different large sleep study.
Hormones regulate things like appetite, metabolism, sex drive, blood pressure and heart rate, body temperature, and circadian rhythms. If the body doesn’t produce adequate hormones due to a lack of sleep, that is thought to lead to chronic health problems in addition to things like fatigue, body aches and problems with blood pressure.
Studies show that a lack of sleep can also increase inflammation, the body’s natural defense against infection or injury. Temporary inflammation works well to protect the body, but if it is chronic, it can lead to multiple diseases.
“Sleep is always one of the biggest pieces of the equation for people to be healthy,” Knowlden said.
“Often, people see the need to sleep as an inconvenience. They think to get the most out of life, they need to deprive themselves of sleep to get ahead or to be more social, but it’s really the other way around,” he said. “Most of the research shows your quality of life actually improves if you get sufficient sleep.”
Knowlden said that when people tell him they’re having trouble sleeping, he offers several recommendations.
First, establish a consistent sleep schedule. Training your body to go to bed at a consistent hour and get up at the same time every day makes getting a regular night’s rest easier.
The bedroom should be dark, quiet and free or pets who can interfere with sleep.
Avoid caffeine, alcohol and large meals before bedtime. Exercise during the day can also lead to better sleep at night.
“The more we can encourage people to get a better night’s rest, the better,” Knowlden said. “Sleep impacts everything.”