What Is Sleep Debt?

Medically reviewed by Kashif J. Piracha, MD

Sleep debt, also known as sleep deficit, is the difference between the amount of sleep your body requires and how much sleep you're actually getting. For example, if you are an adult who should get the recommended seven hours of sleep but only sleep for five hours, you have a sleep debt of two hours.

If you regularly don’t get the recommended hours of sleep each night, sleep debt can add up—potentially impacting your physical and mental health. Making a few improvements to your sleep routine can help you cut down on sleep debt when you notice the deficit affecting your health.

Symptoms of Sleep Debt

In addition to feeling fatigued from a lack of sleep, you might also notice any of the following symptoms if you have sleep debt:

• Decreased alertness

• Inability to focus 

• Problems learning

• Slower reaction times

• Difficulty with problem-solving

• Memory issues

• Mood swings

• Decreased productivity

Symptoms of sleep debt can affect your relationships, work performance, and safety. For instance, data show that when you're sleep deprived, you’re more prone to have a car accident. It's possible to experience the behavioral changes after just one night of sleep debt. The more sleep debt you have, the more severe symptoms can be.

What Causes Sleep Debt?

Your work, home, and social schedules are common reasons you’d experience sleep debt. Many people might find it challenging to block out enough time to sleep. For instance, if you work late into the evening, you may have to go to bed later.

Poor nighttime routines can play a role in sleep debt as well. For instance, keeping phones or other devices in your bedroom can prevent you from getting the proper amount of sleep. One reason for this is because the blue light many electronics emit can interrupt your brain’s production of the hormone melatonin. Melatonin cues your body to feel sleepy. With interrupted melatonin production, you might not fall asleep at a proper time.

Poor sleep habits can also cause sleep debt.  For example, attempting to sleep in an area that makes sleeping more difficult, such as a place that is too noisy, bright, or too cold or too warm can impact your ability to get the hours of sleep you need.

Mental health conditions like anxiety and depression or a sleep disorder like insomnia, sleep apnea, or restless legs syndrome, can also contribute to sleep debt. While it's not an official sleep disorder, sleep anxiety—a cycle of being anxious about not being able to fall or stay asleep—can lead to sleep debt, too.

How To Calculate Your Sleep Debt

Sleep debt is the difference between how much sleep you need and how much sleep you get. To calculate your sleep dept, you first need to know how much sleep you should be getting.

Everyone needs a slightly different amount of sleep to feel fully rested, but here are the recommended amount of sleep per night for different age groups:

Once you know how much sleep you should be getting, you then need to do some subtraction to figure out how short you fell from the recommended hours. For example, if you require eight hours of sleep per night but you've only gotten six hours, your sleep debt for the night is two hours. If you repeatedly miss your recommended eight hours of sleep by two hours each night for a whole week, it adds up to an accumulated sleep debt of 14 hours for the week.

How To Reduce Sleep Debt

Sleep debt can keep building if you don't take steps to reduce it.

To cut down on sleep deficit, it's important to consistently get the amount of quality sleep your body needs to feel fully rested. Some tips on how to get quality sleep include:

• Get ready for bed earlier in the evening.

• Go to bed and wake up at the same time every day as much as possible.

• Keep naps to a maximum of 20 minutes.

• Avoid caffeine, alcohol, and large or heavy meals close to bedtime.

• Keep your sleeping area dark, quiet, and at a comfortable temperature.

• Implement a regular exercise routine during the day.

• Limit electronic device use in the evening, especially right before bed.

Consistency is key when it comes to sleep debt. Make sure that when making up for sleep debt, you make getting the same recommended hours of sleep a regular part of your routine to see improvement rather than oversleeping on random days.

Can You Catch Up on Sleep?

Experts are mixed on whether catch-up sleep, such as oversleeping on the weekend to make up for a lack of sleep during the week, is the most effective way to reduce sleep debt.

Some research suggests that making up for lost sleep on the weekends may contribute to a lower mortality risk, help protect against conditions like non-alcoholic fatty liver disease, and potentially lower your risk of depression.

But other data show that the make-up sleep strategy might have some consequences. In one study, people who resolved their sleep debt by catching up on sleep over the weekend ended up experiencing some negative effects, including higher calorie intake after dinner, increased weight gain, and changes in how the body processes insulin and blood sugar levels. Another study found that recovery sleep was linked to a higher risk of heart disease in older women.

Either way, it's safer to focus on getting the sleep you need in the first place rather than relying on catching up. It's estimated to take around four days for your body and brain to recover from just one hour of sleep debt.

Risks of Long-Term Sleep Debt

Sleep is essential for mental and physical health, so not getting enough of it regularly comes with some potential health risks.

Research shows that having long-term sleep debt may increase your risk of obesity, type 2 diabetes, high blood pressure (hypertension), heart disease, stroke, mental health conditions, and infections like pneumonia. Long-term sleep debt could also potentially decrease life span.

And while it's possible to "get by" with a sleep deficit, research has found that the deficit impacts your quality of life and safety.

When To See a Healthcare Provider

Sleep debt itself isn't a health condition. However, it could be a sign of one. Having sleep debt could be an indication of serious health conditions like narcolepsy, sleep apnea, and insomnia.

Regardless of whether you have a health condition causing your sleep debt, it's important to seek help if you feel you're not getting as much sleep as you should.

Check with a healthcare provider if you consistently feel tired during the day or if sleepiness is interfering with your ability to perform daily tasks. Difficulty getting up in the morning, an inability to focus during the day, or frequent dozing off during the daytime are also signs that you should see a healthcare provider.

If you do fix your sleep debt and get the recommended amount of sleep but still feel tired, that is also a sign to see a healthcare provider. Sleeping more than eight hours per night and still not feeling rested can also be a sign of a sleeping disorder.

A Quick Review

Sleep debt is the time difference between the amount of sleep you should get and the amount of sleep you actually get. Another term for sleep debt is sleep deficit. Busy schedules, poor sleep hygiene, and sleep disorders can cause sleep debt. Over time, sleep debt can add up, potentially taking a toll on your physical and mental health. Rather than solely relying on weekend catch-up sleep, experts recommend improving your current sleep routine to avoid sleep debt altogether.

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