Sleeping and waking up at different times is associated with an increased risk of heart attack and stroke, even for people who get the recommended amount of sleep, according to new research.
While most previous research has measured the impact of sleep length on human health, less is known about the effects of changes to the sleep cycle, said researchers in a statement published Tuesday, reports CNN.
To address this, for seven days, scientists tracked activity data from 72,269 participants aged 40 to 79 who had never suffered a major adverse cardiovascular event.
They calculated each person’s Sleep Regularity Index (SRI) score, with higher scores denoting more regular sleepers.
The team then tracked incidents of cardiovascular death, heart attack, heart failure and stroke over eight years and found that irregular sleepers were 26% more likely to suffer one of these events than those with a regular sleep cycle. Irregular sleep means the variations in the time someone goes to sleep and wakes up.
The 26% calculation also takes into account a number of factors, including age, physical activity, alcohol consumption and smoking that could have influenced the findings. However, it was an observational study and, as such, can only establish a link rather than cause and effect: we can’t know for sure if irregular sleep patterns caused the increased risk.
Researchers also noted that those with a higher SRI score (more regular sleepers) were more likely to get the daily recommendation of seven to nine hours of sleep per night for 18-64 year olds, and seven to eight hours for those over the age of 65, with 61% of regular sleepers doing so compared to 48% of irregular sleepers.
“Our results suggest that sleep regularity may be more relevant than sufficient sleep duration,” the study said.
Lead study author Jean Pierre Chaput, a professor in paediatrics at the University of Ottawa in Canada, told CNN that “an increasing body of research suggests that sleep irregularity may be a stronger predictor of mortality risk than insufficient sleep.”
“Bedtimes and wake-up times don’t need to be exactly the same every day, but it’s best to keep them within 30-60 minutes of your usual schedule to support your body’s natural circadian rhythm,” added Chaput.
“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,” he said.
Chaput also warned against relying on catching up on sleep at the weekends.
The study was published in the Journal of Epidemiology & Community Health.
Bd-pratidin English/Fariha Nowshin Chinika
