How Much Sleep Debt Do I Have? This App Works It Out (2024)

No one likes debt, whether that’s money or sleep. But unlike your finances, it’s hard to figure out how much sleep debt you have.

Online calculators aren’t tailored to how much sleep you personally need, and working it out yourself is almost impossible — not to mention time-consuming.

Luckily, the RISE app works out your sleep debt for you.

Below, we’ll cover what sleep debt is exactly, how you can use the RISE app to find out how much of it you have, and how you can repay your sleep debt to boost your energy levels, productivity, and mood.

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How Much Sleep Debt Do I Have?

How much sleep debt you have will depend on how much sleep you need each night and how much you’ve gotten recently. If you’ve been missing out on sleep, you’ll have sleep debt.

But these things can be tricky to figure out accurately yourself, and online sleep calculators often give out generic — or downright incorrect — advice.

RISE uses a year’s worth of your phone use data and proprietary sleep-science-based models to work out how much sleep you need down to the minute. The app then compares this against how much sleep you’ve been getting recently to calculate how much sleep debt you have.

On a day-to-day basis, RISE automatically tracks your sleep times and recalculates your sleep debt each morning.

We looked at how much sleep debt our users have overall and found some interesting insights. Among our users, on average, women have more sleep debt than men in every age group from the age of 30 onwards.

When it comes to age alone, 18-to-23-year-olds have more sleep debt on average than any other age group. Those under 30 tend to have more sleep debt than those over 30. And the age group with the lowest average sleep debt is those aged 40 to 49.

RISE users on iOS 1.202 and above can click here to view their sleep debt.

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What is Sleep Debt?

Sleep debt is the amount of sleep you’ve missed out on recently. If you need eight hours of sleep, but you only get six, you’ll have sleep debt. And sleep debt keeps building up all the time you don’t get enough sleep.

There are two types of sleep debt:

• Acute sleep debt: This is the short-term sleep debt you get from not getting enough sleep last night, or missing out on sleep in the last two weeks or so.
• Chronic sleep debt: This is the long-term sleep debt you get from months or years of regularly not getting enough sleep.

Sleep scientists agree sleep debt is the most important sleep score out there affecting you’ll feel and perform each day. That’s good news! You don’t need to worry about deep sleep, REM sleep, or sleep quality scores you get from apps and wearables. For the highest energy levels and best health, mood, and productivity, focus on keeping your sleep debt low (more on how to do that soon).

We’ve covered more on what sleep debt is here.

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How is Sleep Debt Calculated?

Sleep debt is calculated by subtracting how much sleep you got recently from how much sleep you need each night. If you fall short, you’ll have sleep debt.

At RISE, we don’t just tally up the hours of sleep you’ve missed, though. We put more weight on last night’s sleep — 15% to be exact. That’s because last night has the biggest impact on how you’ll feel and function today.

The remaining 85% of your sleep debt comes from the 13 nights before this, with more recent nights having more weighting.

And we don’t just compare how much sleep you got to a generic sleep guideline like seven to nine hours of sleep. We work out how much sleep you need down to the minute for an accurate measure of your sleep debt.

According to 2022 research, artificial intelligence may one day be able to tell if you're sleep deprived based on your voice. But for now, the RISE app is a quick, easy, and accurate way of calculating your sleep debt.

How much sleep do I need? Your sleep need is how much sleep you need each night, and it’s highly individual. When we looked at the sleep needs of 1.95 million RISE users aged 24 and up, we found the median sleep need was eight hours. But sleep needs ranged from a tiny five hours to a staggering 11 hours 30 minutes.

RISE users on iOS 1.202 and above can click here to view their sleep need.

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How Much Sleep Debt Should You Aim For?

We recommend you aim for five hours of sleep debt or less. This will help to maximize your energy levels, productivity, and overall health and well-being.

Research shows your mental performance with five hours of sleep deficit may be very close to what it would be with zero.

So, while having no sleep debt at all is great, it’s a goal you may not need to hit. It’s not only unrealistic, it can also stress you out as you’ll worry about every minute of lost sleep. And stress and anxiety can easily keep you up at night, contributing to poor sleep and sleep debt.

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What Are the Symptoms of Sleep Debt?

The symptoms of sleep debt include low energy, trouble concentrating, lowered athletic performance, and feeling irritable in the short term, and weight gain, diabetes, and depression in the long term. But the list doesn’t end there.

Short-term sleep debt can lead to:

• Daytime sleepiness
• Reduced attention span and focus
• Brain fog
• Irritability
• A weakened immune system (a 2023 study found there’s a 27% increased risk of infection in those who get less than six hours of sleep)
• Digestive issues
• Falling asleep while driving

Long-term sleep debt can lead to:

• Diabetes
• Weight gain and obesity
• Cardiovascular disease
• High blood pressure
• Anxiety
• Depression
• Having multiple serious health conditions (a 2022 study found sleeping for five hours or less a night at ages 50, 60, and 70 was associated with a high risk of having two or more chronic diseases like cancer and heart disease.
• Early death

These are the common symptoms, but research suggests we all react differently to sleep deprivation, and acute and chronic sleep deprivation affects our bodies in very different ways. More research is needed to fully understand the effects of sleep debt.

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How Do You Know if You Have Sleep Debt?

You can know if you have sleep debt by subtracting how much sleep you got recently from how much sleep you need. For example, if you need eight hours of sleep, but only get five hours of sleep, you’ll have three hours of sleep debt.

But it’s difficult to figure out our sleep duration exactly, and many of us don’t know how much sleep we need in the first place.

RISE works all this out for you. It calculates how much sleep you need, tracks your sleep times, and automatically works out how much sleep debt you have each morning.

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How Long Does it Take to Recover From Sleep Debt?

How long it takes to recover from sleep debt will depend on how much sleep debt you have. The more you have, the longer it can take to recover. Research suggests one hour of sleep loss takes four days to recover from.

For a personalized answer, RISE’s smart schedule feature tells you how many days it’ll take you to pay back your sleep debt if you follow the app’s recommended sleep and wake times.

A key study on the topic saw participants only get five hours of sleep for seven nights. They then got two nights of recovery sleep. Their energy levels, mood, and reaction times all got worse when they were sleep deprived, but bounced back after the two recovery nights.

Another study saw participants only get six hours of sleep for six nights, then 10 hours of sleep for three nights to recover. Their levels of sleepiness and IL-6 (an inflammatory compound) increased when they were only getting six hours of shut-eye. But they bounced back after the three nights of 10-hour recovery sleep.

Their cognitive performance took a hit and didn’t recover, however. But this may be because participants didn’t sleep enough to fully pay back their sleep debt.

More recent studies show it may be possible to recover from a lack of sleep in the week by getting extra sleep at the weekend. A 2023 sleep study found those who paid down sleep debt at the weekend had a lower risk of high cholesterol compared to those who didn’t catch up on sleep.

But it may take longer to recover if you have a large amount of sleep debt.

One of our sleep advisors at Rise Science is Dr. Jamie Zeitzer, the co-director of the Center for Sleep and Circadian Sciences at Stanford University. He did a study looking at how sleep debt affects work performance. The results showed two consecutive nights of less than six hours of sleep can decrease work performance for six days.

While it may be possible to pay back sleep debt, it’s also not clear what the long-term impacts are of building up sleep debt and paying it back on a regular basis.

Although it can take a while to recover from sleep debt, you can begin paying it back quickly. On average, RISE users who pay back sleep debt in their first two weeks of using the app manage to pay back more than four hours of sleep debt.

You can learn more about whether you can catch up on sleep here.

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How to Repay Sleep Debt?

You can repay your sleep debt by getting more sleep than you usually need. You can get this extra sleep by taking naps, going to sleep a little earlier, or sleeping in a little later.

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Here’s our best advice for each of those options:

• Taking naps: Sleep research shows a two-hour nap after an all-nighter can boost alertness and performance, and reverse increased levels of the stress hormone cortisol. But even a power nap can help chip away at sleep debt. Make sure you’re not napping for too long or too close to bedtime, though, as this can make it harder to fall asleep at night. Keep naps to about 90 minutes (unless in extreme circ*mstances, like after an all-nighter) and take afternoon naps (during your natural afternoon dip in energy), so you’re not sleeping too close to bedtime. Check RISE for the best time to nap each day.
• Going to bed a little earlier: An earlier bedtime can make up for lost sleep. But you want to get the timing right for this, too. If you head to bed too early, you may find yourself struggling to sleep. RISE can show you when your energy levels will be higher in the early evening (when it’ll be almost impossible to sleep) and when your body will start winding down for bed (when you could head to bed). We’ve got more advice on how to sleep early here.
• Sleeping in a little later: An extra hour in bed can make a difference to your sleep debt. Keep lay-ins to an hour or so (two maximum) to avoid messing up your circadian rhythm, or body clock, which can make it harder to fall asleep the next night. If you use RISE as your alarm, the app will tell you if your alarm time will contribute to your sleep debt or not. If it will, set a later alarm time when possible.

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How to Avoid Sleep Debt?

Avoid sleep debt by getting the sleep your body needs each night. You can make that happen with good sleep hygiene. These are the daily behaviors that help you fall asleep, stay asleep, and get quality sleep, night after night.

Here’s what good sleep hygiene looks like:

• Keep a consistent sleep schedule: Try to go to bed and wake up at roughly the same time each day, even on weekends. RISE users with consistent sleep patterns have less sleep debt than those with more inconsistent sleep patterns.
• Get bright light first thing: Aim to get out in sunlight first thing in the morning for at least 10 minutes. If it's overcast or you’re getting light through a window, make that 15 to 20 minutes. Morning light resets your circadian rhythm for the day, which will help you fall asleep that evening.
• Avoid light close to bedtime: Put on blue-light blocking glasses about 90 minutes before bed (we recommend these). Light suppresses the sleep hormone melatonin and so late-night light exposure from screens or artificial lighting can keep you up.
• Avoid caffeine, large meals, intense exercise, and alcohol too late in the day: You don’t have to give them up completely, you just have to get the timing right. RISE can tell you when to avoid each one to stop them messing with your sleep.
• ‍Do a calming bedtime routine: If stress keeps you up, you’re not alone. RISE users say stress and anxiety are their biggest challenges when it comes to getting a good night’s sleep. Try doing a relaxing bedtime routine about an hour before bed to wind down.
• ‍Keep your bedroom dark, cool, and quiet: Set your thermostat to 65 to 68 degrees Fahrenheit, use blackout curtains and an eye mask, and wear earplugs or listen to white noise.

Sleep hygiene is important both when you’re paying back sleep debt and when you’ve already got low sleep debt and want to keep it low. To help you remember it all, RISE tells you when to do 20+ healthy sleep habits each day at the time that makes them the most effective for you.

RISE users on iOS 1.202 and above can click here to set up their 20+ in-app habit notifications.

Get an Accurate Measure of Your Sleep Debt

It can be hard to figure out how much sleep debt you have. You need to know how much sleep you need and how much you’ve been getting recently. Working that out yourself is tricky, and online calculators aren’t much better as many are based on generic guidelines or incorrect calculations.

For an easy and reliable way of finding out how much sleep debt you have, turn to the RISE app. RISE uses algorithms and a year’s worth of your phone use data to tell you how much sleep you need and how much sleep debt you have.

RISE can also guide you through 20+ sleep hygiene habits to make it easier to get better sleep to lower your sleep debt and keep it low.

We’ve found 80% of RISE users get more sleep in five days, so you could start paying back your sleep debt fast.