Here’s some news that will keep you up at night: a lack of sleep later correlates with a higher risk of being diagnosed with multiple chronic conditions like diabetes, cancer, depression, and dementia.
That’s not entirely a surprise—previous studies have shown that not sleeping enough can double your risk of death. But these latest findings, from researchers in Paris and London and published Tuesday in the journal PLoS Medicine better illustrate the role of sleep in preventing—and encouraging—the development of chronic conditions The study found that 50-, 60-, and 70-year-olds who slept at least two fewer hours than recommended were at higher risk for being diagnosed with multiple chronic conditions. Good sleep hygiene may be key to keeping aging populations healthy, wrote the researchers.
It’s common for sleep patterns to change as people age—many find, for instance, that it becomes more difficult to fall asleep and stay asleep as they grow older. Some of these changes may be caused by the deterioration of circadian pacemakers in the brain that regulate our body clock, but there are also longstanding questions about how disease affects and is affected by sleep.
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The researchers set out to understand the connection between sleep and chronic disease risk across different ages, where people’s sleep patterns are naturally changing. They analyzed self-reported sleep data and diagnoses of chronic diseases among thousands of British civil servants, then looked at members of the cohort at ages 50, 60, and 70 who were free from chronic disease at the time.
They found that at age 50, people who slept five hours a night or fewer were 1.3 times likelier than people who slept seven hours to develop multiple chronic conditions. This risk increased slightly for people aged 60 and 70. The researchers did not find a significantly increased risk of developing chronic conditions among 50-year-olds who slept nine or more hours a night, in part because relatively few people in their sample reported experiencing this duration of sleep.
Even as the definition of sleep health changes as people age, the finding that a shorter duration of sleep consistently increased the risk of chronic disease diagnoses suggests that this metric might be useful as a red flag for care providers to investigate further in their patients.
Still, the association between sleep and disease risk, though well-supported in previous research, is not the same as a causal link. The researchers wrote that the findings leave open the possibility of reverse causality—in other words, that chronic conditions not yet diagnosed may have led cohort members to sleep less, due to pain or circadian disruption.
Important to note, too, is that the study may suffer from a type of selection bias known as the healthy worker effect. People who are employed (in this instance, as civil servants) are more likely to be healthy than the general population, meaning the results of the study may not apply to broader, more diverse groups of people.
Future research may look at the clinical utility of using sleep as an early diagnostic of a wide range of diseases, perhaps even before current tests pick them up. Such work would allow us all to sleep a bit easier.
