Going to sleep at a different time every night? Here's why you should avoid it

The study adds to growing evidence about the critical role of sleep consistency in overall health.

Irregular sleep schedules may pose a greater threat to cardiovascular health than previously thought, according to a new study. Research published in the Journal of Epidemiology & Community Health revealed that individuals with inconsistent sleep routines were at a significantly higher risk of major cardiovascular events, such as heart disease and stroke, regardless of whether they achieved the recommended seven to nine hours of sleep per night.

The findings mark a shift in focus from sleep duration to the stability of sleep-wake cycles as a critical factor for heart health.

“Our results suggest that sleep regularity may be more relevant than sufficient sleep duration in modulating the risk of major adverse cardiovascular events (MACE),” the researchers stated.

Study Design and Key Findings

The study involved 72,269 participants aged 40 to 79, all of whom had no prior history of heart disease or stroke. Each participant wore an activity tracker for one week to monitor their sleep patterns. Using this data, researchers calculated a Sleep Regularity Index (SRI) score for each individual.
• Scores above 87 indicated a regular sleep pattern.
• Scores below 72 denoted irregular sleep patterns.
• Scores in between were classified as “moderately regular.”

Over the following eight years, researchers tracked incidents of stroke, heart failure, and heart attacks among the participants. The findings were stark:
• Participants with irregular sleep patterns were 26% more likely to experience a major cardiovascular event compared to those with regular schedules.
• Those with moderately regular sleep schedules had an 8% higher risk.

Additionally, the study found that individuals with regular sleep patterns were more likely to achieve the recommended amount of sleep: seven to eight hours for people over 65 and seven to nine hours for those aged 18 to 64.

Making Up for Lost Sleep Ineffective

Notably, the research indicated that trying to “catch up” on sleep to compensate for irregular patterns did not mitigate the associated cardiovascular risks. This reinforces the importance of maintaining a consistent sleep schedule rather than simply focusing on total sleep duration.

Limitations of the Study

While the findings are significant, the study had several limitations:
1. Sleep data was collected over just one week, which may not fully capture long-term sleep patterns.
2. The activity tracker used could not differentiate between actual sleep and conscious resting.
3. Napping, which can influence overall sleep health, was not accounted for.

Broader Implications

The study adds to growing evidence about the critical role of sleep consistency in overall health. Previous research primarily concentrated on sleep duration, but this study highlights the potential dangers of irregular sleep routines, even among those who achieve sufficient rest.

For individuals aiming to improve cardiovascular health, the findings underscore the importance of prioritising a stable sleep-wake schedule alongside other lifestyle factors such as diet, exercise, and stress management.