The findings from a study published in the journal Sleep highlight that sleep regularity, defined as the day-to-day consistency of sleep-wake timing, is a powerful predictor of mortality risk. The Sleep Regularity Index (SRI) was calculated from over 10 million hours of data from 60,977 participants in the UK Biobank.

The study found that a higher SRI was associated with a 20 to 57 percent lower risk of mortality, even after adjusting for various factors such as age, sex, ethnicity, lifestyle and health biomarkers. Sleep regularity was associated with lower risks of all-cause, cancer and cardiometabolic mortality across the top four SRI groups compared to the least regular group. Importantly, sleep regularity outperformed sleep duration as a predictor of mortality risk, indicating its potential as an important predictor of health and longevity. Further research is needed to establish causality and explore the underlying mechanisms.