It is not just a lack of sufficient sleep that affects a person’s health, a new study suggests. Having irregular sleeping patterns may contribute to the risk of cardiovascular problems, according to recent evidence.
Scientists already know that sleep is of utmost importance to health. Research has shown that without sufficient sleep, pretty much every aspect of health is affected, from cognitive functioning to immunity.
But even people who sleep for a good number of hours each night may face increased risks to their health if their sleep is irregular — that is, if the hours they sleep vary wildly from night to night, or if their bedtime and wake-up time change a lot.
A new study by researchers from Brigham and Women’s Hospital in Boston, MA, has found that people who have very irregular sleep patterns are more likely to experience cardiovascular events than those with more regular sleep.
The study’s authors report their findings in the Journal of the American College of Cardiology and stress the importance of good sleep hygiene.
“When we talk about interventions to prevent heart attacks and stroke, we focus on diet and exercise,” notes lead author Tianyi Huang.
He continues, “Even when we talk about sleep, we tend to focus on duration — how many hours a person sleeps each night — but not on sleep irregularity and the impact of going to bed at different times, or sleeping different amounts from night to night.”
“Our study indicates that healthy sleep isn’t just about quantity but also about variability and that this can have an important effect on heart health.”
– Tianyi Huang.
More than twofold increase in risk
The researchers analyzed data from 1,992 older participants in their 60s and 70s with no cardiovascular problems at baseline.
The participants were of various ethnicities, including African Americans and Chinese Americans, with all the data coming from the Multi-Ethnic Study of Atherosclerosis.
The team was able to map the participants’ sleeping patterns as they had each agreed to wear an actigraph unit — an activity tracking monitor worn on the wrist — over a period of 7 days.
This allowed researchers to obtain information about participants’ bedtimes, sleep durations, and wake-up times.
The researchers also had access to health follow-up information, covering an average period of 4.9 years.
Over that period, a total of 111 participants experienced different cardiovascular events, such as heart attacks and strokes.
The research team noticed that participants who displayed the most irregular sleep patterns — those with 2 hours or more difference in sleep duration each night — had a more than twofold increase in the risk of cardiovascular problems, in comparison with those with 1 hour or less difference in sleep duration.
Even after adjusting for other risk factors for cardiovascular problems, the investigators saw that the association between irregular sleep patterns and cardiovascular events remained significant.
“Although we also observed that participants with irregular sleep tended to have worse cardiometabolic risk profiles at baseline, adjustment for established [cardiovascular disease] risk factors (e.g., blood pressure, lipids, diabetes, etc.) only explained a small portion of the associations between sleep irregularity and [cardiovascular disease] risk,” they write in their study paper.
Still, the current research was not without its limitations. The investigators explain that the cohort whose data they had access to was relatively small, and the follow-up time not quite long enough to render the link between sleep patterns and cardiovascular risk unquestionable.
However, the team notes that should further studies confirm their findings, they will be interested in finding out whether modifying a person’s sleep patterns could reduce their risk of heart and vascular problems.
“Sleep regularity is a modifiable behavior. In the future, we’d like to explore whether changing one’s sleep patterns by going to bed consistently each night may reduce a person’s risk of future cardiovascular events,” Huang says.
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