When we pull an all-nighter to study for a test or put together a presentation, we assure ourselves we’ll just make it up later—but can you really catch up on lost sleep?
The amount of sleep needed varies by person, but the National Sleep Foundation has settled on 7 to 9 hours a night. One-third of Americans aren’t even reaching the low number of that scale, and those who sleep less than 7 hours a night, on average, are considered sleep deprived. Unfortunately for them (or us), that sleep debt builds up … and it never quite goes away.
If you’ve lost more than five hours of sleep this week, or it’s been more than a few days since that sleepless night, you may as well cut your losses—gaining that sleep back is scientifically unlikely. Dr. Raghu Reddy, pulmonologist at the University of Arkansas for Medical Sciences and a sleep medicine specialist, says the body can recover up to five hours of lost sleep; beyond that, the body has to scramble to adjust to the sleep deprivation, sometimes by skipping straight to the REM stage of sleep instead of wasting time in less-beneficial stages. Short-term sleep recovery is supported by Martha Jefferson Hospital Sleep Medicine Center’s medical director Dr. Christopher Winter as well, who says that “recovery sleep in the short term does work,” but never specifies a duration for that short-term span.
Not that they encourage people to use those facts as an excuse to neglect sleep. A study published by the American Physiological Society show that sleep-deprived people didn’t improve on attention tests even after a period of recovery sleep. The test mimicked a normal week: six hours of sleep for six nights, followed by three nights with ten hours of sleep, and showed that that pattern doesn't negate the effects of sleep loss. A 2003 Walter Reed Institute of Research study corroborated this failure to recuperate brain performance with extra sleep; researchers said that “the brain adapts to chronic sleep restriction” and performs “at a reduced level” for days—or maybe even longer—after the sleep has been recovered.
Not only does it take longer than a few days to get back to normal after missing sleep; your sleep debt actually accumulates, and switching up your sleep patterns can throw off your ability to recover. UT Southwestern Medical Center’s sleep medicine specialist cautions against sleeping at different times every night, which would delay one’s circadian clock; instead, fall asleep eight hours before waking up for best sleep-recovery results. Lawrence Epstein, medical director of Sleep HealthCenters, advises months of regular sleep patterns to erase your sleep debt, and the previously-mentioned Dr. Reddy encourages “good sleep hygiene,” including relaxing routines before bed, avoiding stimulating activities or beverages (coffee, for example, and alcohol), and keeping strict times for sleeping and waking in order to keep your circadian clock happy.
Sleep is commonly sacrificed in favor of productivity or a fun night out, but sleep deprivation can lead to problems like declined memory retention, obesity, and early death. The good news, though, is that there are studies suggesting you can bank sleep in advance of snooze-less nights in order to counteract the sleep deprivation, which is helpful if you plan your sleep schedule carefully.