NEW YORK • Here is a wake-up call. The negative health effects of skimping on sleep during the week cannot be reversed by marathon weekend sleep sessions, according to a new study.
Researchers have long known that routine sleep deprivation can cause weight gain and increase other health risks, including diabetes.
But for those who force themselves out of bed bleary-eyed every weekday after too few hours of shut-eye, hope springs eternal that shutting off the alarm on weekends will repay the weekly sleep debt and reverse any ill effects.
The research, published in Current Biology, crushes those hopes.
Despite complete freedom to sleep in and nap during a weekend recovery period, participants in a sleep laboratory, who were limited to five hours of sleep on weekdays, gained nearly 1.3kg over two weeks and experienced metabolic disruption that would increase their risk for diabetes over the long term.
While weekend recovery sleep had some benefits after a week of insufficient sleep, the gains were wiped out when people plunged right back into the same sleepdeprived schedule on Monday.
If there are benefits of catch-up sleep, they're gone when you go back to your routine... These health effects are long term. It's kind of like smoking once was - people would smoke and wouldn't see an immediate effect on their health, but people will say now that smoking is not a healthy lifestyle choice.
MR KENNETH WRIGHT, director of the sleep and chronobiology laboratory at the University of Colorado
"If there are benefits of catch-up sleep, they're gone when you go back to your routine. It's very short-lived," said Mr Kenneth Wright, director of the sleep and chronobiology laboratory at the University of Colorado, who oversaw the work.
"These health effects are long term. It's kind of like smoking once was - people would smoke and wouldn't see an immediate effect on their health, but people will say now that smoking is not a healthy lifestyle choice. I think sleep is in the early phase of where smoking used to be."
Mr Clifford Saper, head of neurology at Beth Israel Deaconess Medical Centre, called the study "convincing and fascinating".
Mr Michael Grandner, director of the sleep and health research programme at the University of Arizona College of Medicine, said the study reinforces the point that people need to stop thinking of sleep as a balance sheet.
Imagine a person who ate nothing but cheeseburgers and french fries on weekdays, but dined only on celery and kale on weekends and tried to call that a healthy diet, he noted. Drastically cutting calories all week and then bingeing on a giant pizza on Saturday would not restore equilibrium, either.
That, Mr Grandner noted, is what people are doing when they skip sleep on weekdays with the idea that they can make up for it on the weekend.
"When you're talking about something as complex as metabolism, it's very much about balance and equilibrium, and when you're chasing numbers of hours and you're trying to make them all add up, that's not about balance," Mr Grandner said.
Mr Wright said the study suggests people should prioritise sleep - cutting out optional "sleep stealers" such as watching TV or spending time on electronic devices.
Even when people do not have a choice about losing sleep due to childcare duties or job schedules, they should think about prioritising sleep in the same way they would a healthy diet or exercise.
As for understanding the long-term impacts of short sleep on the weekdays and long bouts on the weekend, it will be important to extend research beyond the artificial conditions and short timeframe of a laboratory experiment.
The researchers also found an intriguing gender difference, in which women got less recovery sleep on the weekends and also were able to restrain their eating behaviour better than men on the weekends - but experienced the same metabolic dysfunction, as measured by impairments in how their body responded to blood sugar.
"These were incredibly healthy people, with no medical problems, no psychiatric disorders, no drug use, no medications, no sleep problems, nothing at all - so when we put them on these types of schedules, they have the best possible outcomes, they have the lowest risk of any adverse health outcome as far as we can tell," Mr Wright said.