The much-loved weekend snooze stems from the need to catch up on sleep lost during the week.
"That's an attempt to pay-back sleep deprivation," says Charles Czeisler, chief of the Division of Sleep and Circadian Disorders at the Brigham and Women's Hospital, in Boston.
But Czeisler is not an advocate of sleeping late at the weekend. He calls it "sleep binging," and says it's a break from consistency that leads to further disruption of our sleep cycles.
Sleep takes place in cycles of Rapid Eye Movement (REM) sleep and slow-wave sleep (Non-REM sleep) that alternate in approximately 90-minute cycles.
The extra hours of sleep, but more importantly the later time of awakening, at the weekend, lead to confusion and displacement in the body when people return to their weekday routine -- something Czeisler defines as "social jet lag."
"If you're getting up at 6 am and then noon, that's the equivalent of Boston to Paris [in time zones]," he says.
It's a form of sleep bulimia with this chronic binging
Charles Cseizler, Brigham and Women's Hospital
Making a habit of this is not a healthy lifestyle to lead, according to Czeisler. "It's a form of sleep bulimia with this chronic binging," he says. Such cycles disrupt sleep integrity, meaning people miss vital moments in their sleep cycle, such as REM cycles.
Even worse, in Czeisler's view, is the "crash and burn" cycle many live by where they skimp on sleep and drive themselves to the point of exhaustion, and then crash.
"[This] has adverse health consequences ... it's better to have consistency of sleep," he says.
Value your sleep
It's worth paying attention to the hours you spend sleeping, and in bed, as a means of monitoring and maintaining your health and wellbeing.
"Duration, timing and quality of sleep are the key factors," says Czeisler.
More studies are needed to truly understand the causes of the links seen between excessive sleep and various health conditions, but for the time being it may be wise to avoid those weekend binges and instead inject some routine into your dreams.