United States: Shift work is a condition where an individual changes his or her cycle of sleeping and waking up, and it increases the rate at which one can have a heart attack or stroke regardless of the hours put to sleep, a new study shows.
Prior studies focused more on the influence of sleep length versus alterations to the timing of sleep, said the researchers in their Tuesday statement, as reported by CNN News.
Monitoring Sleep Regularity
To solve this concern, over seven days, 72,269 participants aged from 40 to 79 with no history of a major adverse cardiovascular event were monitored for activity data.
Evaluating the observed graphs, they distributed Sleep Regularity Index (SRI) scores to every individual, and the higher score corresponded to higher regularity in sleeping.
The team then followed instances of cardiovascular death, heart attack, heart failure, and stroke for eight years and realized that those with irregular sleep were 26% more prone to these and other such electrical incidents than the regular sleepers. Irregular sleep is the changes in the time by which the person gets to bed and is able to wake up.
Likewise, the 26 % calculation has also considered other influences such as age, physical activity, alcohol consumption, and smoking in the results obtained. However, it was an observational study and, as such, can only establish a link rather than cause and effect: we are unable to establish whether irregularities in the sleep cycle contributed to the increase in risk.
Sleep Regularity and Its Effect on Health
The authors also observed that having a higher SRI score (more frequent sleepers) better met the daily recommended sleep duration for individuals 18-64 years (7-9h) and patients over the age of 65 (7-8h) – only 61% of whom meet this criteria as opposed to 48% of those with an irregular sleep schedule.
Moreover, even in the subgroup of irregular sleepers who reported that they got 7-8 hours per night, they had a higher risk of a major cardiovascular event.
“Our results suggest that sleep regularity may be more relevant than sufficient sleep duration,” the study said.
The Importance
The lead study author, Jean Pierre Chaput, a professor in pediatrics at the University of Ottawa in Canada, speaking to CNN, said that “several studies have indicated that sleep desynchrony could actually offer a higher risk for death than sleep deficiency.”
When it comes to the risk of heart diseases, Chaput noted that high blood pressure is one of the most significant risk factors.
“Readers should prioritize seven to nine hours of consistent, restorative sleep per night, as poor sleep can contribute to high blood pressure,” he said.
Sleep Patterns and Long-Term Health Risks
“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.
“It’s possible to recover some sleep by sleeping longer on weekends, but it doesn’t fully undo the negative effects of chronic sleep deprivation during the workweek,” he said.
“While extra weekend sleep can temporarily improve mood and cognitive function, irregular sleep patterns can disrupt your body’s circadian rhythm and lead to long-term health risks like obesity, diabetes, and heart disease,” added Chaput, who is currently developing healthy sleep guidelines in collaboration with the WHO.
“I believe it’s a crucial next step to ensure sleep is valued as an essential component of well-being rather than dismissed as a waste of time in our society,” he said.
Caution Against Overstating Causality
Naveed Sattar of the University of Glasgow in Scotland, a professor of Cardiometabolic medicine, commented that while there are links between sleep cycles and cardiovascular health, the language used in the study was overly causal.
‘There might be other aspects in people’s lives, for example, if they took a glass of alcohol in the night before going to sleep, then sleeping in cycles is not necessarily the cause of such diseases, nevertheless, it could be the other way round,’ he said in the interview with CNN on Thursday.
“It’s very hard to say,” said Attar, adding that he “would be cautious in attributing causality here.”