Everything You Need to Know About Sleep Debt

For example, if you need eight hours of sleep a night but you consistently only sleep six hours, you’re accumulating 14 hours of sleep debt every week. The more you borrow from your sleep bank, the more your body and mind pay for it—and the longer it will take to “pay it back”.

What are the effects of sleep debt?

You probably know that a lack of sleep can leave you feeling run-down the next day, but there’s more to the sleep deprivation issue. Rafael Pelayo, a sleep specialist at the Stanford Sleep Medicine Center, says sleep restores the body by cleansing the brain of toxins with cerebrospinal fluid. Plus, when you’re asleep, your whole body rests—your kidneys even make less urine. So when you’re not getting enough sleep, you’re cutting yourself short on these restorative processes.

A one-off restless night isn’t the end of the world; that’s why we can survive jet lag or getting up every two hours to care for a hungry baby or a puppy who hasn’t been house broken yet. “Our brains are built to push off sleep…we can do without sleep in certain circumstances without falling apart,” Pelayo says. “If you skip sleep for a night, you will feel it, but you can still more or less function to some degree.”

But that kind of sleep deprivation isn’t sustainable, because when you’re not sleeping, your body doesn’t have a chance to complete processes critical for your well-being. One study found people who got less than six nightly hours of sleep over the course of just one week were four times more likely to catch a cold.

In the long-term, sleep debt can have literally ill effects, according to Seth Rinderknecht, a family medicine doctor at Eskenazi Health in Indianapolis. Research on sleep deprivation shows long-term sleep debt can lead to conditions like insulin resistance and heart disease; another study found fragmented sleep can lead to the acceleration of cancer growth.

Long-term sleep debt may also contribute to chronic medical conditions like hypertension, heart disease, diabetes, memory loss, cardiovascular disease, and an increased risk for stroke. “It’s more than just irritability and tiredness,” explains Rinderknecht. “Chronic sleep deprivation can increase your risk for serious, life-threatening medical problems.”

Is it possible to catch up on the sleep you’ve missed?

To prevent the effects of sleep deprivation on the body and improve overall well-being, Pelayo says it’s important to prioritize sleep like you might, say, eating nutritious food. Getting into a regular sleep routine is key, because research shows that resolving sleep debt is not as simple as “repaying” the rest you lost during the week tacking on some extra zzzs come Saturday. In one study, individuals with sleep debt experienced ongoing impairment in cognitive function for weeks, even when they slept in a few extra hours on the weekends.