In a recent Journal of Sleep Research study, short, but not long, weekend sleep was associated with an increased risk of early death in individuals under 65 years of age. In the same age group, either short sleep or long sleep on both weekdays and weekends showed increased mortality when compared with consistently sleeping 6-7 hours per day.
The link between sleep duration and mortality seems to be easier to understand when considering the analysis of the joint effects of weekday and weekend sleep, the authors noted. "The results imply that short (weekday) sleep is not a risk factor for mortality if it is combined with a medium or long weekend sleep," they wrote. "This suggests that short weekday sleep may be compensated for during the weekend, and that this has implications for mortality."