It doesn’t matter how long you sleep, it’s WHEN you go to bed

For most adults these days, achieving the goal of seven hours sleep a night is a stretch. 

And yet, scientists at Duke University are here to add one more thing to your well-being to do list: set a strict bed time.

Most of us think of bed time as something for children; once you hit college, any time is fair. 

However, new research published today in the journal Scientific Reports shows adults who don’t stick to a regular schedule are more often heavier, less healthy, with higher blood sugar levels and higher blood pressure. 

A new study on sleep patterns suggests that a regular bedtime and wake time are just as important for heart and metabolic health among older adults, Duke researchers found

The researchers said it’s not clear whether those symptoms are the things that cause people to have more erratic sleep, or whether erratic sleep causes those symptoms.

‘Perhaps all of these things are impacting each other,’ said Jessica Lunsford-Avery, PhD, an assistant professor in psychiatry and behavioral sciences and the study’s lead author. 

But either way, she concludes, after assessing 1,978 people, that striving for a solid seven hours between the same times every night can’t hurt your chances of keeping your health in check. 

‘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.’ 

Dr Lunsford-Avery’s study gave each participant, aged 54 to 93, a device that tracked sleep schedules, specific to the minute, so her team could monitor the smallest of changes. (They could tell, for example, whether someone nodded off at 10.10pm when their usual pattern is 10pm.)

They found that people with hypertension tended to sleep more hours, and people with obesity tended to stay up later.

But crucially, they found the regularity of a person’s sleep was the best measure to predict a person’s heart and metabolic disease risk.   

Irregular sleepers were also more likely to report depression and stress than regular sleepers, both of which are tied to heart health.

African-Americans had the most irregular sleep patterns compared to participants who were white, Chinese-American or Hispanic, the data showed.

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,’ Dr Lunsford-Avery said.

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

Her team plans to conduct more studies over longer periods in hopes of determining how biology causes changes in sleep regularity and vice-versa.

‘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.’