London, UK – August 19, 2025 

A new study has revealed a significant link between irregular sleep patterns and a higher mortality risk. While previous research has focused on the number of hours of sleep, this study indicates that maintaining a consistent sleep-wake schedule may be even more crucial for long-term health. The findings, published in a leading medical journal, suggest that consistently varying bedtime and wake-up times can increase the risk of dying from a variety of causes, regardless of whether a person gets the recommended amount of sleep.

Headline Points:

 * Consistency Over Quantity: The study suggests that sleep regularity may be a stronger predictor of mortality risk than sleep duration alone.

 * Higher Risk for Irregular Sleepers: Individuals with highly irregular sleep schedules were found to have a significantly increased risk of all-cause and cardiovascular mortality.

 * The “Social Jet Lag” Effect: The research highlights how the common practice of sleeping in on weekends to “catch up” on sleep can disrupt the body’s natural circadian rhythm, a phenomenon sometimes referred to as “social jet lag.”

 * A New Health Metric: The findings point to the need for a greater focus on sleep regularity in public health guidelines and clinical practice as a simple, effective target for improving overall health and survival.

The Dangers of a Disrupted Body Clock

For years, the public health message around sleep has primarily focused on the magic number: seven to nine hours a night. This new research, however, adds a critical dimension to the discussion. It reveals that the timing and consistency of sleep may be a more significant factor in health outcomes than the total number of hours.

The study, which analyzed a large cohort of individuals over several years, used objective data from wearable accelerometers to track sleep-wake cycles, providing a more accurate measure than traditional self-reported data. The results were clear: participants with the most irregular sleep patterns had a substantially higher risk of premature death compared to those who maintained a consistent schedule.

The biological explanation behind these findings lies in the body’s circadian rhythm, an internal clock that regulates a host of vital functions, from hormone production to metabolism.  When a person’s sleep-wake times vary from day to day, their circadian rhythm becomes disrupted. This disruption can lead to a cascade of negative health effects, including chronic inflammation, hormonal imbalances, and impaired immune function. Over time, these issues can increase the risk of developing chronic diseases such as heart disease, type 2 diabetes, and even certain cancers, all of which contribute to a higher mortality rate.

One particularly concerning finding was that the increased risk for irregular sleepers remained even if they were getting the recommended seven to nine hours of sleep per night. This suggests that the body is not simply counting the hours; it is looking for rhythm and predictability. The study’s authors suggest that this is a powerful wake-up call, as many people believe that they can make up for lost sleep during the week by sleeping in on the weekends, but this practice may be doing more harm than good by continuously resetting the body’s internal clock.

The findings have significant implications for public health. They suggest that health care providers should start asking patients about their sleep regularity in addition to their sleep duration. Simple behavioral changes, like going to bed and waking up at the same time every day, including on weekends, could be a powerful, underappreciated tool for improving long-term health and well-being.