Regular bedtime beneficial for adults too!

Not only does a regular bedtime improve sleep quality, it is just as important for heart and metabolic health among older adults, finds a study.

In a study of 1,978 older adults, researchers at Duke Health and the Duke Clinical Research Institute found people with irregular sleep patterns weighed more, had higher blood sugar, higher blood pressure, and a higher projected risk of having a heart attack or stroke within 10 years than those who slept and woke at the same times every day.

Irregular sleepers were also more likely to report depression and stress than regular sleepers, both of which are tied to heart health. The findings show an association -- not a cause-and-effect relationship -- between sleep regularity and heart and metabolic health.

"From our study, we can't conclude that sleep irregularity results in health risks, or whether health conditions affect sleep," said Jessica Lunsford-Avery, study's lead author. "Perhaps all of these things are impacting each other."

Still, the data suggest tracking sleep regularity could help identify people at risk of disease, and where health disparities may impact specific groups.

"Heart disease and diabetes are extremely common in the United States, are extremely costly and also are leading causes of death in this country," she said. "To the extent we can predict individuals at risk for these diseases, we may be able to prevent or delay their onset."

As one might expect, irregular sleepers experienced more sleepiness during the day and were less active -- perhaps because they were tired, Lunsford-Avery said.

"Perhaps there's something about obesity that disrupts sleep regularity," Lunsford-Avery said. "Or, as some research suggests, perhaps poor sleep interferes with the body's metabolism which can lead to weight gain, and it's a vicious cycle. With more research, we hope to understand what's going on biologically, and perhaps then we could say what's coming first or which is the chicken and which is the egg."

The study appears in the journal Scientific Reports.