Did you have a sleep-in this Bank Holiday Monday? Were you chastised by someone close to you because you were engaging in a bad habit? Well I’ve some good news for those of us partial to an occasional lazy morning in bed.
Sleep experts have been firm in their lack of belief in the possible health benefits of sleep banking or catch-up sleep. Matthew Walker, neuroscientist and sleep expert, and author of the best-selling Why We Sleep, says "You can't accumulate a debt and pay it off at a later point in time. If I were to deprive you of sleep an entire night, and then in a subsequent night give you all the sleep you want, you never get back all that you've lost."
But now a new study has challenged conventional thinking. Researchers at Stockholm University confirmed that adults who managed up to five hours of sleep every night increased their risk of mortality.
However, when people who only slept five hours a night during the week compensated by getting nine hours shut-eye a night on the weekends, their risk of death did not increase.
The study, published in the Journal of Sleep Research, looked at data on sleep habits collected from more than 38,000 people under 65 years of age. Researchers then followed these people for 13 years, comparing their mortality rates. They excluded factors like education, body mass index, and smoking that might have confounded the results.
“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,” the study authors said. “This suggests that short weekday sleep may be compensated for during the weekend, and that this has implications for mortality.”
Risk of mortality
Of course their conclusion that long weekend sleep may compensate for short weekday sleep does not trump the ideal: the research confirmed that people who slept seven hours consistently did not heighten their risk of mortality.
“Sleep duration is important for longevity,” said Torbjörn Åkerstedt, lead author of the study, adding that researchers had previously looked at links between sleep duration and mortality but had focused on sleep during the working week.
“I suspected there might be some modification if you included also weekend sleep, or day-off sleep.”
However the latest research confirmed a paradox noted in previous studies: people who slept for eight or more hours, seven days a week, were found to have a 25 per cent higher mortality rate compared with those who kept to six or seven hours a day.
The study does not prove a cause and effect relationship between catch-up sleep and greater longevity.
Among its limitations was that participants were only asked about their sleep patterns at one point in time during the research period.
But it does offer hope to the many who struggle with our “always on” work culture.
If you are a night owl it is especially difficult to fit in seven to eight hours sleep a night, leaving you a daily battle to rise in time for work.
For many people burning the candle at both ends seems unavoidable, which makes the latest research findings of a positive benefit to paying off sleep debt particularly appealing.
A literature search confirmed there is little prior research that has looked at paying off sleep debt. What there is suggests that banking sleep (having longer periods of time dedicated to sleep in bed), and napping after periods of sleep deprivation can decrease daytime sleepiness, improve mood and cognitive functioning, sharpen reaction times, and improve physical performance.
And there is no denying the substantial body of evidence that not getting enough sleep is linked to an increased risk of obesity and heart disease, as well as dementia. There’s also evidence that sleep deprivation can contribute to a lower sex drive, reduced fertility, and lower mood.
To die, to sleep . . . perchance?