As kids, most of us had a designated bedtime when our parents told us it was time to wind down and get some shuteye. As we get older, however, we have control over our own schedules. But while you don't have anyone telling you to turn off the lights at 8 p.m. sharp, it may be worth it to keep yourself on a stricter schedule. According to a new study, going to bed and waking up at different times can increase your risk of "major cardiovascular events," including heart attack and stroke.
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The research, published in the Journal of Epidemiology & Community Health, included 72,269 participants between the ages of 40 and 70 from the UK Biobank study. According to a press release, participants wore activity trackers for seven days to record sleep and calculate their Sleep Regularity Index (SRI) score. This index "compares sleep-wake patterns between consecutive days," the study explains.
People with a score over 87 had a regular sleep pattern, and those with a score below 72 were irregular sleepers. Those with a score between 72 and 87 were "moderately irregular sleepers." More people in the "regular sleeper" group got the recommended amount of nightly sleep—seven to nine hours for those between the ages of 18 and 64 and seven to eight hours for people over 65.
Researchers then compared these scores with incidents of death from cardiovascular events, as well as instances of heart attack, heart failure, and stroke over the following eight years.
Irregular sleepers were found to have a 26 percent higher risk of these health events than regular sleepers, and moderately irregular sleepers had an 8 percent higher risk.
Interestingly enough, even if irregular sleepers got the recommended amount of sleep, they still had an increased risk of major cardiovascular events.
"Our results suggest that sleep regularity may be more relevant than sufficient sleep duration in modulating MACE [major adverse cardiovascular event] risk," the study authors wrote.
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In the press release, they added, "Findings from this study suggest that more attention needs to be paid to sleep regularity in public health guidelines and clinical practice due to its potential role in cardiovascular health."
Speaking with CNN, lead study author Jean-Philippe Chaput, PhD, professor in the department of pediatrics at the University of Ottawa in Ontario, Canada, noted that while you don't have to stick to an exact time for sleeping and waking, you should try to stay within 30 to 60 minutes of your typical times.
"Small variations are fine, but consistent sleep patterns improve sleep quality, boost mood and cognitive function, and lower the risk of health issues like heart disease and diabetes," Chaput told the outlet.
However, the research was not without limitations. In the press release, the authors noted that the study was observational and couldn't show direct cause and effect. (This is achieved in a randomized control trial, which is the gold standard in scientific research.)
They also stated that sleep was only tracked for one week, and even though there were many participants, the data "may not accurately reflect the UK population." The activity trackers didn't log a difference between "quiet wakefulness and sleep," nor did researchers factor in napping to SRI scores.
