What Is Sleep Debt?

Craig Primack, MD, FACP, FAAP, MFOMA

Reviewed by Craig Primack, MD, FACP, FAAP, FOMA

Written by Rachel Sacks

Published 05/28/2024

Updated 05/25/2024

Between work, kids, and Netflix, you might find yourself staying up later and later and getting less and less sleep, racking up “sleep debt” as a result. But what is sleep debt, exactly, and just how bad is it for your body?

The bad news is, not getting enough sleep can affect your health in a number of ways, from weight management to cognitive function. The good news? There are ways to recover from sleep debt and get your nights back on track. 

Read on for a better understanding of the consequences of sleep debt and tips for how to catch up on sleep. 

Sleep debt, also known as a sleep deficit, occurs when you don’t get enough quality sleep. Effectively, the difference between the amount of sleep one gets and the amount of sleep one needs is what’s known as sleep debt. 

Sleep deprivation, meanwhile, is the condition that occurs when you don’t get enough sleep. Sleep deprivation can lead to sleep debt and vice versa. 

Here’s an example further illustrating these distinctions: If you were to get six hours of sleep one night but your body needed eight hours, your sleep debt is two hours. If you were to continue your poor sleep habits, the sleep debt would add up, leading to sleep deprivation.

If you’re wondering if sleep debt is real, just consider the impacts it can have on your health. 

You may know that not getting enough sleep can affect your mood. But accumulating sleep debt doesn’t just leave you feeling crankier — it can lead to serious health consequences as well.

1. Fatigue

This may be an obvious one, but a short-term effect of not getting enough sleep is feeling fatigued and sleepy during the day. This is because sleep recharges your batteries — you store up energy while you sleep since you’re using fewer bodily functions. 

As a result, the more hours you rack up in sleep debt, the less energy you’ll have.

2. Weight Gain

Sleep debt can also affect your weight, either making weight loss difficult or causing weight gain and obesity. That said, some studies suggest that the connection between sleep deprivation and weight gain seems to be more common in women than in men.

Sleep deprivation can lead to weight gain because it disrupts your levels of ghrelin and leptin, which are hormones that regulate your appetite and control how hungry or full you feel. 

When you get a good night’s sleep, your body produces healthy ghrelin and leptin levels, so that you can go about your day with an appetite for an appropriate caloric intake. Lack of sleep, however, may lead to higher food intake and the consumption of more calorie-dense foods.

3. Mental Health Issues

Ever notice you feel more stressed out or in a lower mood after a few days of poor sleep? As it turns out, long-term one of the effects of sleep deprivation is on your mental health. 

In fact, sleep deprivation has been tied to increased anxiety and depression, among other mood disorders.

4. Increased Risk of Chronic Diseases

Another effect of accumulated sleep debt? An increased risk of health problems like cardiovascular conditions, including high blood pressure (also known as hypertension), heart disease, heart failure, and more.

A lack of sleep can also weaken your immune system over time, leading to a higher risk of illness and infection.

5. Impaired Cognitive Function

Even the most mundane tasks can feel like they require Herculean effort after a bad night’s sleep. And as it turns out, sleep deprivation can impair your cognitive and motor functions, making it hard to perform in the workplace and safely do things like driving.

One small study of 48 participants found that chronically getting six or less hours of sleep per night resulted in the cognitive impairment equivalent of going two full nights with no sleep.

Sometimes, losing sleep is inevitable. So, how do you catch up on sleep when that happens?

Your first thought might be sleeping in on the weekends. And as it turns out, spending more than two hours over the weekend catching up on sleep can reduce the prevalence of cardiovascular disease when you're getting less than six hours of sleep per weekday night.

Napping may also come to mind when trying to recover from sleep debt. Indeed, one study found that taking a nap can help with sleep recovery, offering benefits in terms of performance and reduced sleepiness for up to 12 hours after the nap. Even a short nap — think just 10 minutes — may leave you feeling more refreshed and alert.

But while napping and sleeping in on the weekends can help, it can take more than that to return the body to its pre-sleep debt state. 

If you lost just one hour of sleep, research suggests that it would take up to four days to totally recover from that lost sleep, and up to nine days of sufficient sleep to eliminate the sleep debt entirely.

Now that you know that regular sleep loss can affect your well-being and that recovering from sleep debt isn’t a quick undertaking, how can you improve your sleep?

According to the Centers for Disease Control (CDC), you should aim to get at least seven hours of sleep each night, though the necessary amount of sleep can vary from person to person. Here are some tips to consider to improve your sleep hygiene, and thus your sleep:

  • Keep a sleep schedule. Going to bed at the same time each night and waking up at the same time every morning — even on weekends — will help you regularly get enough sleep. That’s because a consistent sleep schedule helps maintain your body’s circadian rhythm, or your body’s sleep-wake cycle.

  • Practice good sleep habits. Implementing good sleep hygiene, or good habits around when you go to sleep and wake up, will help improve your sleep quality and ensure you get adequate sleep. Avoid caffeine or large meals close to bedtime, and minimize the use of electronic devices like TVs and phones in your bedroom.

  • Create a sleep-friendly environment. Speaking of removing electronics from the bedroom, your sleep environment — including its noise levels, temperature, and amount of light — can affect how you sleep. Aim to keep your bedroom quiet, dark, and at a comfortable temperature to get better sleep.

  • Talk to your doctor. If you’ve implemented the above tips but are still struggling with sleep, seek medical advice from a healthcare provider. They can rule out any medical conditions or sleep disorders like sleep apnea by ordering a sleep study, or they may recommend a sleep medicine.

Now and then, we all miss out on a little sleep, whether it’s due to a late night or a lot of tossing and turning. But if those nights become routine, you’ll end up with some serious sleep debt — and that sleep deprivation can have very real consequences. 

Here’s a recap on what to know about not getting enough sleep:

  • What is sleep debt? Sleep debt results when you don’t get enough sleep, or a high enough quality of sleep. Generally, adults need at least seven hours of sleep per night.

  • Why does sleep debt matter? Sleep debt can affect your health in both the short- and long-term, leading to issues like weight gain and obesity, weakened immune function, decreased cognitive performance, and the development of health conditions like heart disease and hypertension.

  • How can you recover from sleep debt? You can make up somewhat for lost sleep through getting extra sleep on the weekends and napping. But to avoid chronic sleep debt, you’ll need to improve your sleep hygiene. You might consider setting regular bedtimes and wake-up times, and making your bedroom as  sleep-friendly as possible (think blackout curtains and a white noise machine).

How much sleep you get and the quality of that sleep is important for your overall health. But of course, when it comes to certain health challenges, such as weight loss, sleep is just one piece of the equation — and you may not be able to solve it yourself. If you need more help getting healthy sleep or addressing other other health issues, consider talking to a healthcare provider.

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Craig Primack, MD, FACP, FAAP, FOMA

Dr. Craig Primack MD, FACP, FAAP, FOMA is a physician specializing in obesity medicine.

He completed his undergraduate studies at the University of Illinois and subsequently attended medical school at Loyola University — The Stritch School of Medicine. 

He completed a combined residency in Internal Medicine and in Pediatrics at Banner University- Phoenix, and Phoenix Children's Hospital. He received post-residency training in Obesity Medicine and is one of about 7,000 physicians in the U.S. certified by the American Board of Obesity Medicine.

In 2006, Dr. Primack co-founded Scottdale Weight Loss Center in Scottsdale, Arizona, where he began practicing full-time obesity medicine. Scottsdale Weight Loss Center has grown since then to six obesity medicine clinicians in four locations around the greater Phoenix Metropolitan area.

From 2019–2021, he served as president of the Obesity Medicine Association (OMA), a society of over 5,000 clinicians dedicated to clinical obesity medicine. He has been on the OMA board since 2010, currently serving as ex-officio trustee.

Dr. Primack routinely does media interviews regarding weight loss and regularly speaks around the country educating medical professionals about weight loss and obesity care. He is co-author of the book, “Chasing Diets.”

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