A new study carried out by researchers from Children’s Hospital of Eastern Ontario Department of Pediatrics and Research Institutebelonging to the University of Ottawa in Canada, has confirmed that an irregular sleep-wake cycle is associated with a increased risk of cardiovascular events major events, such as heart attacks and strokes, even for those who sleep the recommended nightly hours.
These findings suggest that sleep regularity may be more relevant than sufficient sleep duration in modulating cardiovascular risk.
The study, published in the ‘Journal of Epidemiology & Community Health’, analyzed the data from 72,269 people between 40 and 79 years old who participated in the UK Biobank study and none of whom had a history of major cardiovascular events.
Participants wore a tracker for 7 days
Participants wore an activity tracker for 7 days to record their sleep, and sleep score was calculated. Sleep Regularity Index (SRI) of each person. Those with an SRI score above 87 were considered regular sleepers, while those with a score below 72 were classified as irregular sleepers.
Over the next 8 years, participants’ incidents of cardiovascular death, heart attack, heart failure, and stroke were collected. After taking into account various influencing factors, such as age, physical activity levels, the consumption of alcohol and tobacco, Among others, people with irregular sleep were found to be 26% more likely to suffer a major cardiovascular event compared to those with a regular sleep-wake cycle. For their part, people with moderately irregular sleep were 8% more likely.
What is the Sleep Regularity Index (SRI)?
The Sleep Regularity Index (SRI) is a measure used to assess the consistency and regularity of a person’s sleep patterns. It is calculated from data recorded by an activity tracker, which monitors the sleep-wake cycles for a set period, usually a week.
The SRI takes into account variability in bedtime and wake times, as well as sleep duration. A high SRI score indicates a regular sleeping pattern, while a low score suggests irregular or inconsistent sleep.
The importance of sleep regularity on health
This study highlights the importance of maintaining a regular sleep pattern for cardiovascular health. Although it is recommended to sleep between 7 and 9 hours per night for adults 18 to 64 years old, and between 7 and 8 hours for those over 65 years old, the results suggest that Sleep regularity may be even more relevant than sleep duration in the modulation of cardiovascular risk. This means that maintaining consistent bedtime and wake-up times can be just as important as getting enough sleep.
The researchers acknowledge some limitations in the study, such as the fact that the UK Biobank may not accurately reflect the country’s population, and sleep patterns were evaluated over a single week. However, the findings highlight the need to pay more attention to sleep regularity in public health guidelines and clinical practice due to its possible role in cardiovascular health.
Tips to improve sleep regularity
To maintain a regular sleep pattern and thus promote cardiovascular health, some practices are recommended such as:
Set fixed hours to go to bed and wake up, even on weekends.
Create a relaxing routine before bed, avoiding the use of electronic devices at least one hour before bedtime.
Keep the bedroom cool, dark and quiet to promote an environment conducive to sleep.
Avoid the consumption of caffeine, alcohol and heavy foods in the hours before going to sleep.
Perform regular physical activity, but not too close to bedtime.