Debunking Myths about Sleep Debt
The most obvious scenario of sleep debt occurs when you stay up late to work or study, grab only a few hours of sleep, and then during the next few nights you notice sleeping more hours than usual, assuming circumstances permit. Virtually everyone appreciates this acute sleep loss generates a short term sleep debt that more or less resolves with extra sleep received that same week.
More common than the acute scenario is the conundrum about long-term sleep loss: can a person erase some or all the debt incurred over months or years of insufficient sleep?
I personally researched this question in the summer of 1986. I had completed 7 years of medical school and internal medicine residency training and chose to spend the next six months monitoring how much sleep I received by sleeping whenever the urge arose. In the first month, July, I slept roughly 11.5 hours in every 24-hour period, usually 9.5 hours at night coupled with two separate naps, typically 30 min at late morning and 1.5 hours at late afternoon.
Rarely did my part-time urgent care job interrupt my efforts, throughout which I tracked not only total sleep but also how much the recovery of lost sleep affected my energy level and well-being. By August, I slept in the 11.0 hour range but still experienced three sleep periods of 9.5 hrs at night, 30 min mid-morning and 1 hr in the afternoon.
Although feeling noticeably better in mood and cognition, it was interesting to experience persisting daytime sleepiness that I would dissolve into hoping to erase more sleep debt. By the third month (September) I was sleeping 10.5 hours total, comprised of ~9.5 hours at night, 15 min most mornings, and a 45 min afternoon siesta.
During waking hours, I felt more alert and refreshed than at any other time in the previous 7 years. The next two months dropped to 9 hours at night and one nap with total sleeping hovering around 9.5 hours. Finally, in the last month, I dropped to 8.5 hours at night coupled with more inconsistent desires to nap during the day. Nonetheless, I still ended up napping 2 or 3 times per week if circumstances permitted, but now daytime napping led to reductions in the next night’s sleep hours.
Though this information is anecdotal, it persuaded me to appreciate some sleep debt can be erased over a longer and sustained effort, which seems contrary to what is discussed in the scientific literature. For example, supposedly initiating CPAP should bring a person back to a normal total of sleep hours after a few weeks of use, but I find this perspective difficult to believe.
My sense is maximizing sleep quality is the surest pathway to drawing down your sleep debt. And, unfortunately, it requires months or years to achieve an optimal response to CPAP. On the other hand, those on advanced PAP devices may generate higher sleep quality much sooner and therefore would be predicted to erase sleep debt much faster, yet still over a lengthy period of time.