What is sleep debt, and is it possible to catch up? Sleep experts say the answer is ‘complex’

For some, sleep can be one of the best parts of the day — but for others, getting enough sleep can be a bit more challenging.

Nearly 33 percent of working adults reported sleeping six or fewer hours a night, according to a 2020 review by the Centers for Disease Control and Prevention, despite its recommendation that adults need seven or more hours of sleep for optimum health and wellbeing.

And the National Sleep Foundation, a nonprofit dedicated to improving public health and well-being through sleep education, found in a 2020 poll of over 1,000 American adults that they feel sleepy, on average, “three days a week,” with many saying it impacts their daily activities, mood and productivity.

It’s more than just our mood that suffers when we don’t get the sleep we need: According to the American Academy of Sleep Medicine's 2021 position statement, "sleep is essential to health." The AASM states that not getting enough sleep increases the risk of diabetes, cardiovascular disease and cancer. It’s also linked to reduced immune function, metabolic dysregulation and obesity.

If that isn't enough to give you sleep anxiety, experts tell Yahoo Life that the more sleepless nights we have, the more we accumulate what’s known as “sleep debt.”

What sleep debt is — and why quality matters

We all require a certain amount of sleep to function at our best. When we shortchange it, we acquire a “sleep debt," says Dr. Sanford Auerbach, an associate professor of neurology at Boston University’s School of Medicine, who notes that the average adult requires between seven and nine hours a night.

“So if you're supposed to get seven hours of sleep, and you only get five, that can lead to a debt of two hours,” Auerbach tells Yahoo Life. When that happens, "you don't function quite as well the next day, and it accumulates over time,” as do negative impacts on cognitive function, such as “slower reaction times” to daily tasks.

Dr. Rachel Salas, a professor of neurology at Johns Hopkins Medicine, tells Yahoo Life that sleep debt is "more complex" than people might realize.

“Of course, everyone thinks they're special, like, ‘I only need five hours or six hours,’ but some people are just better at compensating than others," Salas explains. Plus, it’s less about the amount of time we sleep and more about the quality of sleep we’re getting.

You may be clocking in the appropriate hours of sleep, but that doesn't mean you're getting the quality sleep you need, she explains. Things like "inconsistent wake times and bedtimes" can negatively affect your sleep, which can further add to your sleep debt.

Another factor affecting the quality of one's sleep is napping — both the timing during the day and the duration.

An easy rule to live by, Salas says, is to keep naps at around 30 minutes. Anything more, such as an hour-long nap, might be felt as a sleep cycle, and interfere with the quality of your nighttime sleep — as can napping past 3pm.

“People like to say, ‘Oh, I took a nap. I was asleep for like five hours or four hours,’ which is very common if you’re a shift worker. But that's not a nap. That's a sleep period,” Salas says. “If you're taking a one-hour nap at 7pm, well, guess what? That's going to affect your circadian rhythm and will affect your sleep onset. That's going to mess with the timing of your sleep schedule — and insomnia can kind of creep in.”

It’s important to note the difference between insomnia and sleep deprivation, Auerbach says, explaining that those with insomnia have trouble falling asleep, while those who are considered “sleep deprived” simply have not allocated enough time to sleep.

Other causes of sleep deprivation

Salas says people can have underlying issues that may be impacting their quality of sleep — such as undiagnosed sleep apnea, depression, anxiety and menopause.

Salas points out that 80 percent of people who have obstructive sleep apnea are not diagnosed. She shares that patients will say, "'Wait, I don't know what the problem is. I get eight hours of sleep, or close to it, and I'm still so tired,' so they don't take that extra step to say, ‘Maybe there's something going on here.’”

Dozing off at meetings (no matter how boring) or even falling asleep within five minutes of hitting the pillow at night could be signs of trouble — “not necessarily for apnea," Salas says, but it could mean that "something sleep-related is going on.” She adds that women experiencing menopause are also more likely to go undiagnosed with sleep issues such as apnea.

"Women suffer more from the consequences of undiagnosed and untreated sleep apnea," Salas explains. “They're not the typical patient somebody might think about when you have apnea, which tends to be somebody overweight or a man. So for women, they might be underweight and actually have significant apnea because they have other risk factors, like [being] postmenopausal.”

Another major barrier that interferes with quality sleep, Auerbach adds, is perhaps one of the most obvious: stress.

“It's a matter of effective stress management,” he says, as a general rule of thumb to getting good sleep. “Insomnia, particularly, is related to stress in many, many ways."

But can you "catch up" on sleep debt?

While catching up on sleep is possible in the short-term, it gets more complicated in the long-term.

“If you had an all-nighter or you're somebody who had a long shift, or just have something major going on in your life and you did not get any sleep, you can acutely make that up in the next day or two,” Salas explains. “You can oversleep, or stay in and sleep, and you're going to be able to pay some of that [sleep debt] back. But chronically? No.”

Salas continues: “If you've been chronically sleep deprived for weeks, years, months, there's nothing you're going to do [to pay back sleep debt],” adding: “I can't say, ‘You're this much sleep deprived, so here's what you have to do to pay all that back. And all of that time and all that risk that was associated with your poor sleep, it's all going to be taken away, because now you've paid it back.’ That does not happen.”

All is not lost, though: Naps can be hugely helpful for feeling more rested, as can making lifestyle changes to prioritize sleep going forward.

At the end of the day, Auerbach says the only way we can fix our sleep problems is to take it night by night. "Make sure that the bed is a relaxing place," he advises, a definition "which can vary from person to person."

Having a positive mindset also helps, says Salvas, such as saying to yourself: "'You know what? If I do XYZ, that's going to help my sleep,'" she says. "There's something to be said about setting that positive intention."

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