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New United States research has found that keeping a regular sleep schedule, going to bed and waking up at the same time each day, could be just as important for heart health as how much sleep you get each night.

Carried out by researchers at Duke Health and the Duke Clinical Research Institute, the new study looked at 1,978 older adults age 54 to 93 who were asked to wear tracking devices each night for seven days to record their sleep.

The devices tracked sleep schedules by the minute so the researchers could see whether even subtle changes in bedtime or wake time were linked to the participants’ health.

The findings, published in the journal Scientific Reports, showed that participants with irregular sleep patterns were more likely to be obese, had higher blood sugar, higher blood pressure, and a higher projected risk of having a heart attack or stroke within the next 10 years than those who went to bed and woke up at the same times every day.

Those who had an irregular sleep schedule were also more likely to feel sleepy during the day and be less active, perhaps due to feeling more tired, and were also more likely to report depression and stress, psychological factors also linked with heart health.

The team also found that African-Americans had the most irregular sleep patterns compared to participants who were white, Chinese-American or Hispanic.

The study also measured the duration of participants’ sleep and their preferred timing, whether they were a night owl or preferred going to bed early, but it was sleep regularity that was best at predicting someone’s heart and metabolic disease risk.

However, the team noted that although the findings show an association between a regular sleep timetable and metabolic health, they do not show cause-and-effect.

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

“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.” JB

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