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

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. 

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

Read on to discover:

• How to calculate your sleep debt — manual methods to try and how the RISE app tells you precisely how much sleep debt you have.
• How to repay your sleep debt — strategies to boost your energy levels, productivity, mood, and more.

How Much Sleep Debt Do You 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. 

Sleep debt builds up each night you don’t get enough rest. The more sleep debt you have, the worse you’ll typically feel and function. 

There are two types of sleep debt:

• Acute sleep debt: This is the short-term sleep debt you accumulate from not getting enough sleep last night, or missing out on sleep in the last few weeks. At RISE, we measure this over your last 14 nights. 
• Chronic sleep debt: This long-term debt builds up over months or years of regular sleep deprivation and is harder to measure directly. 

While chronic sleep debt can affect your long-term health, sleep scientists agree it’s acute sleep debt that has the biggest day-to-day impact on how you feel and perform. 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 acute sleep debt low (more on how to do that soon). 

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.

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

How RISE Calculates How Much Sleep Debt You Have

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. It then compares this against how much sleep you’ve been getting recently for a precise calculation of your sleep debt.

At RISE, we don’t just tally up the hours of sleep you’ve missed. We put more weight on last night’s sleep—15% to be exact—because it 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 weighted more heavily.

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

How much sleep do you 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.

We cover how to find out how much sleep you need here.

Other Ways to Find Out How Much Sleep Debt You Have

You can estimate your sleep debt without using an app by paying close attention to your body’s signals. Here are a handful of ways to assess:

1. Track Your Sleep Duration: Over a week, keep a simple log of how many hours you sleep each night. Compare this to how much sleep you need. For every night you fall short, that deficit adds to your sleep debt.
2. Pay Attention to Your Wake-Up: If you regularly wake up feeling groggy, disoriented, or hitting the snooze button, it’s a sign that you might have sleep debt.
3. Daytime Symptoms: Monitor your energy levels and focus throughout the day. If you find yourself needing caffeine or feeling unusually fatigued, it could suggest sleep debt. Other symptoms of acute sleep debt include brain fog, irritability, digestive issues, and falling asleep while driving or microsleeps at work.
4. Weekends vs. Weekdays: If you tend to sleep longer on weekends, this could indicate that you’re catching up on sleep debt accumulated during the week.

But it’s not always easy to tell how much sleep debt we have. It’s difficult to figure out our sleep duration exactly, many of us don’t know how much sleep we need in the first place, and we can adapt to sleep loss. 

One study found people who thought they got enough sleep slept for more than three hours longer than usual when they were given the chance to sleep for 12 hours. And another study found participants were largely unaware of their cognitive performance decreasing as they built up sleep debt. 

Research also suggests we all react differently to sleep deprivation, and acute and chronic sleep deprivation affect our bodies in very different ways.

To help you know once and for all, RISE works out your sleep need and whether you’re carrying any sleep debt. The app automatically keeps track of your sleep debt each night, so you can easily see if it starts creeping up or if you’re paying it back. 

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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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How to Lower Your 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. 

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 circumstances, 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. 

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.

How to Avoid Sleep Debt

The best way to keep your sleep debt low is to prevent it from accumulating in the first place! You can do this by getting the amount of sleep your body needs each night. This is possible through good sleep hygiene—daily behaviors that help you fall asleep, stay asleep, and enjoy 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.