Impact of Sleep Duration on Mortality in Sweden

Study Overview

Researchers from Europe and the United States have investigated how both weekday and weekend sleep durations affect mortality rates in Sweden. In a society where sleep deprivation is prevalent, understanding the implications of sleep patterns is crucial, as inadequate sleep has been linked to increased mortality. Many individuals attempt to compensate for lost sleep during the week by sleeping in on weekends. This raises an important question: Does weekend sleep effectively mitigate the risks associated with insufficient sleep on weekdays?

Examining Sleep Patterns

With this query in mind, researchers analyzed sleep duration data from a cohort of individuals in Sweden over a 13-year period. Most existing studies on sleep do not differentiate between weekend and weekday sleep, typically focusing on average sleep durations throughout the week. The findings were published in the Journal of Sleep Research.

Study Participation and Methodology

Participants in this study were drawn from the Swedish National March Cohort (SNMC), a group formed during a fundraising event organized by the Swedish Cancer Society in 1997. Participants completed a comprehensive health questionnaire, including inquiries about their sleep habits. They reported their sleep duration for both workdays and weekends, with response options ranging from less than 5 hours to 9 hours or more. The researchers defined short sleep as less than 5 hours and long sleep as 9 or more hours, using 7 hours as the baseline reference. After excluding incomplete responses, the study included data from 38,015 participants.

A follow-up was conducted 13 years later, in 2010, to assess mortality among participants. At that time, 3,234 deaths had been recorded, providing a basis for analyzing the relationship between sleep habits and mortality.

Key Findings on Sleep and Mortality

The study sought to compare mortality rates against the baseline of participants who averaged seven hours of sleep per night. Notable results include:

– For participants under the age of 65, short sleep on weekends was linked to a 52% increase in mortality risk.
– Participants under 65 who reported sleeping 5 hours or less during both weekdays and weekends exhibited a 65% higher mortality rate.
– Sleeping longer on weekends did not correlate with increased mortality for those under 65 who slept short hours during the week.
– A higher mortality risk was also identified in individuals under 65 who consistently slept 9 hours or more on both weekdays and weekends.
– No significant association between sleep duration and mortality was observed in participants older than 65 years.

As participants aged, the disparity between weekday and weekend sleep durations diminished, nearing zero for those over 65. Specifically, while weekday sleep duration remained stable, weekend sleep duration gradually decreased.

Limitations of the Study

The authors acknowledged certain limitations in the study. Participants might have misinterpreted the phrase “day off,” and since sleep duration was self-reported at baseline only, the study could not track changes in sleep behavior over time.

Conclusion: The Benefits of Weekend Sleep

The primary takeaway from this research is that individuals under 65 years old face increased mortality risk when they sleep too little or too much on weekdays and weekends. However, those who extend their weekend sleep after a week of insufficient rest may experience a compensatory effect. Thus, sleeping in on weekends appears to confer health benefits. Further research is necessary to clarify the exact relationship between sleep patterns and mortality.

Written by Raymond Quan, MASc, MBA
Reference: Akerstedt et al. “Sleep duration and mortality – Does weekend sleep matter?” J Sleep Res. 2018; e12712.