The surprising impact of your bedtime regularity on your heart 💔

The idea that sleeping eight hours a night is the key to a healthy heart is being questioned. A new study reveals that the regularity of sleep schedules could play an even more decisive role. This often-overlooked detail could transform our nighttime habits.


Canadian researchers have explored the link between sleep regularity and cardiovascular risks. By analyzing data from more than 72,000 individuals, they observed that irregular sleep increased the risk of heart attack, stroke, or heart failure by 26%. This finding applies even to those who follow the recommended sleep duration.

These results, published in Journal of Epidemiology & Community Health, are based on objective measurements. Unlike simple questionnaires, accelerometers recorded participants' sleep cycles over seven days, ensuring an unprecedented level of accuracy.

To assess regularity, scientists calculated a Sleep Regularity Index (SRI). High scores indicate a stable rhythm, while low scores reflect significant variations. Three groups were formed: regular sleepers, moderately irregular sleepers, and irregular sleepers.

The conclusions are striking: any deviation from the usual bedtime or wake-up time increases risks to cardiovascular health. The lower the SRI score, the greater the danger, even when respecting the recommended seven to nine hours of sleep.

The study also highlights that moderately irregular sleepers can reduce their risks by maintaining an adequate sleep duration. In contrast, this strategy is ineffective for irregular sleepers.

Jean-Philippe Chaput, the lead author, emphasizes: “A deviation of more than one hour severely disrupts the biological clock.” He advises limiting schedule variations to 30 minutes, even on weekends.

However, this research remains observational. Although it establishes a strong correlation, it does not prove a direct causal link. Other factors such as diet or stress could influence these results.

Despite these limitations, this work underscores the importance of consistent rhythms to preserve our health. From now on, simple discipline in your schedule could become a valuable ally for your heart.

What is the Sleep Regularity Index (SRI)?

The Sleep Regularity Index (SRI) is a measure used by scientists to quantify the consistency of a person's sleep schedule. It reflects daily variations in bedtime, wake-up time, and total sleep duration.

A high SRI score, generally above 87, indicates very regular sleep schedules. In contrast, a low score (below 71) reveals significant irregularity in sleep cycles, which can disrupt the body's internal biological clock.

The calculation of this index is based on tracking sleep data over several days, often using devices such as accelerometers. These devices measure physical activity to estimate periods of sleep and wakefulness.