Stratified analyses on age revealed individuals 65 years plus old and short sleep (5 hr) during weekends associated with a 52% higher mortality rate

Are you getting concerned yet? 

You should, because when "Cox proportional hazards regression models with attained age as time‐scale were fitted to estimate multivariable‐adjusted hazard ratios and 95% confidence intervals for mortality" it soon becomes clear you definitely should sleep in during the weekend. 9 hours plus sleep recommended.

"The mortality rate among participants with short sleep during weekdays, but long sleep during weekends, did not differ from the rate of the reference group. Among individuals ≥65 years old, no association between weekend sleep or weekday/weekend sleep durations and mortality was observed. In conclusion, short, but not long, weekend sleep was associated with an increased mortality in subjects <65 years. In the same age group, short sleep (or long sleep) on both weekdays and weekend showed increased mortality. Possibly, long weekend sleep may compensate for short weekday sleep."

It is advised you find the right ratio, because oversleeping every day of the week also put participants at a greater risk of mortality.

Short read and Good night.