It's Not Just How Much Sleep You Get That Matters — It's WHEN You Fall Asleep, Too

If you hear the term "regular bedtime" and cringe, then listen up: This one's for you. It's not uncommon for even those of us with the best-laid plans to find ourselves toeing the line of a midnight snooze time one day and then playing catch-up by sleeping in the next. Not only does this habit usually lead to less sleep over time, but according to a new study1, the irregularity itself could be negatively affecting your heart health and metabolism.

Researchers at the Duke University Medical Center took a look at about 2,000 older adults to dissect their sleeping patterns and how a regular (or irregular) bedtime affects their overall health. For seven days, each volunteer wore a sleep-tracking device to chart their slumber patterns, and they also took notes in a sleep diary. Researchers then used the results, in addition to medical information about the participants, to calculate a 10-year projected risk of various cardiometabolic diseases. People with irregular bedtimes were more at risk of having a higher BMI, higher blood pressure, and higher amounts of type 2 diabetes markers like blood sugar and hemoglobin A1, and they were more likely to have a heart attack or stroke in the next decade. And just to make things a smidgen worse: These inconsistent sleepers also tended to have more perceived stress and depressive symptoms.

"We can't conclude that sleep irregularity results in health risks, or whether health conditions affect sleep. Perhaps all of these things are impacting each other," study author Jessica Lunsford-Avery, Ph.D., told Medical News Today, adding that it’s a chicken-or-egg situation.

While more research is needed to clarify the findings, one thing is for sure: The link between sleep irregularity and cardiometabolic risk is notable. These findings suggest even small variations in your sleep patterns can affect your health, meaning it's not just about the number of hours you clock at night with your eyes closed. If you're someone who tends to fall into patterns of so-called social jet lag—that is, getting behind on sleep over the course of a few days and then trying to make up for it all at once over the weekend—you'll want to take some steps to improve the quality of your shut-eye, starting with stabilizing a bedtime schedule.