A team of researchers from the University of Ottawa (Canada) has confirmed that not adhering to a consistent sleep schedule—specifically, the times you go to bed and wake up—can increase the risk of stroke, heart attack, and heart failure by 26 percent. This finding holds true even for those who get enough hours of sleep.
Previous studies have focused on the duration of nighttime sleep and its impact on health, with experts recommending seven to nine hours of sleep per night. This advice remains relevant. However, researchers are now paying more attention to sleep patterns, particularly the dangers of irregular sleep. This refers to variations in the times when a person falls asleep and wakes up.
What Did the New Study Reveal?
According to the latest findings, even eight hours of sleep is insufficient to offset the harmful effects of an inconsistent bedtime and wake-up time.
The large-scale study involved 72,269 individuals aged 40 to 79, who continuously wore sleep trackers to monitor their sleep patterns. Researchers then calculated a Sleep Regularity Index (SRI) for each participant.
This index reflected daily variations in bedtime, wake-up time, total sleep duration, and nighttime awakenings. Participants received scores ranging from 0 (very irregular sleep and wake patterns) to 100 (perfectly regular sleep and wake patterns).
Volunteers were categorized into groups based on their sleep regularity: those with irregular sleep (SRI scores below 71.6), moderately irregular sleep (SRI scores between 71.6 and 87.3), and regular sleep (SRI scores above 87.3). The team then monitored these participants over eight years.
Even after accounting for factors that could influence the results, those who slept irregularly were 26 percent more likely to suffer from stroke, heart failure, or heart attack compared to those who maintained a regular sleep schedule. Meanwhile, individuals with moderately irregular sleep experienced these health issues 8 percent more frequently, as reported by The Guardian.
The study found that the majority of those who slept regularly (61 percent) adhered to the recommended sleep duration, compared to only 48 percent of those who slept irregularly.
Interestingly, among those with moderately irregular sleep, the risk of developing cardiovascular diseases decreased if they were getting adequate rest. It’s worth noting that the recommended sleep duration for adults aged 18 to 64 is 7-9 hours, while for those aged 65 and older, it is 7-8 hours.
Expert Recommendations
The lead author of the study, Jean-Philippe Chaput, emphasized, “We should aim to wake up and go to bed within 30 minutes of the same time, including on weekends. A one-hour variation is less ideal, and zero variation is best.”
According to the researcher, if you don’t have a regular sleep schedule one or two days a week, it won’t be detrimental. However, if your sleep is consistently irregular, it becomes a chronic issue.
It’s particularly important to wake up at the same time each day. Irregular wake-up times disrupt the body’s internal clock, which can have negative health consequences.
“If you need to catch up on lost sleep over the weekend, it’s better to go to bed earlier than to sleep in. Try to wake up at the same time even on Saturday and Sunday,” Jean-Philippe Chaput stressed.
The results of the study were published in the Journal of Epidemiology and Community Health.