18 Mar The Key is Consistency: Sleep Regularity Index reflects lower risk of all-cause mortality.
Sleep duration and quality are widely considered essential components for overall health, although recent studies support that how consistently we sleep may be just as significant. Three recently published articles help to illustrate the importance of maintaining a regular sleep-wake schedule and further support why it is increasingly viewed as a significant public health concern.
The critical article “Consistency is key: sleep regularity predicts all-cause mortality” analyses the parameter of sleep regularity. Sleep regularity can be defined as how consistent a person’s sleep and wake times are from day to day. The authors of this study measured this using a specialised scoring system, the Sleep Regularity Index (SRI), which reflected how similar an individual’s sleep wake patterns were across a period of consecutive days. Higher scores were achieved by individuals with more consistent sleep patterns.
A strength of this article came through its ability to utilise the data from more than 60,000 participants in the UK Biobank. The study analysed sleep patterns recorded through participants completing 7 days of actigraphy during visits, participants were further followed up over the course of several years. The findings presented were significant showing individuals with the most regular sleep schedules had 30% lower risk of mortality from all causes and 38% lower risk of cardiometabolic mortality. Interestingly, while sleep duration was also found to predict mortality incidence, SRI produced larger minimum risk estimates for each mortality outcome aside from cardiometabolic deaths. These results further suggest that maintaining consistent sleep times may be just as crucial as achieving the commonly recommended 7-9 hours of sleep each night.
Further evidence performed in varying populations substantially highlight the importance of sleep consistency. A previous study examining elite team sport athletes reported that individuals with more regular sleep schedules experienced better sleep efficiency, essentially a higher proportion of time spent in bed was actual sleep. Controlling for total sleep duration, between regular and irregular sleep wake time participants, the group with consistent sleep patterns had less variability in sleep quality, pointing towards more restorative sleep.
Moreover, sleep research performed on professional rugby union athletes similarly demonstrated that athletes who maintained regular sleep routines experienced longer total sleep time, fewer nighttime awakenings as well as higher sleep efficiency than those with irregular sleep patterns. Furthermore, this highlights how consistent sleep supports physical recovery and performance in those populations who rely heavily on optimal physical and cognitive function.
Combining these bodies of work, recent research supports that sleep consistency is not simply a personal lifestyle preference but a crucial determinant of population health. Previously, public health initiatives have focused on encouraging adequate sleep duration, although growing evidence supports that regular sleep timing may be an equally important factor for health promotion.
Overall, encouraging consistent sleep behaviours such as maintaining consistent bedtimes and wake times every day may help reduce the risk of chronic disease and further improve overall wellbeing. In a modern day society where lifestyles feature disrupted natural sleep patterns through shift work, travel, and digital technology use, addressing sleep regularity may prove to be an important strategy for refining health outcomes across the population.
Faris M Zuraikat, Brooke Aggarwal, Sanja Jelic, Marie-Pierre St-Onge, Consistency is key: sleep regularity predicts all-cause mortality, Sleep, Volume 47, Issue 1, January 2024, zsad285, https://doi.org/10.1093/sleep/zsad285
Halson SL, Johnston RD, Piromalli L, Lalor BJ, Cormack S, Roach GD, Sargent C. Sleep Regularity and Predictors of Sleep Efficiency and Sleep Duration in Elite Team Sport Athletes. Sports Med Open. 2022 Jun 17;8(1):79. doi: 10.1186/s40798-022-00470-7.
Teece A, Beaven CM, Suppiah H, Argus CK, Gill N, Driller MW. Routine, Routine, Routine: Sleep Regularity and its Association with Sleep Metrics in Professional Rugby Union Athletes. Sports Med Open. 2024 May 9;10(1):51. doi: 10.1186/s40798-024-00709-5.