What Is Slept Debt And How Do You Fix It?

Imagine that on Monday night, things are busy at home - the kids aren’t playing ball or you end up in a heated discussion with your partner. You get into bed late. On Tuesday night, you’re up after dark finishing some work. You go into bed late, again. On Wednesday night, you watch multiple episodes of your new favourite show to relax. You miss your bedtime for the third time in a row. On Thursday, you meet friends for dinner and end up home later than you expected. Fourth night late to bed - check. 

We could spend hours telling you about the importance of sleep, but with the pace and pressures of modern life, the reality is that not getting enough hours of shut-eye is a common occurrence for many of us. 

Whether it’s the constant demands of your family and personal life, a busy job (or multiple jobs or shift work), studies, travel, high stress, or simply staying up late, there are a number of factors that can negatively impact your sleep and take away precious hours of rest. So when that happens, and you’re in a state often referred to as ‘sleep debt’, how quickly can your body really repay it?

What is sleep debt?

According to the Sleep Foundation, sleep debt (aka a sleep deficit), results from getting less sleep than you need each night. For most people, the ideal amount of sleep i is around 7-9 hours. Slept debt can build progressively day by day and start to take its toll on your health in a myriad of ways, affecting the functioning of your brain and your body. 

For someone who needs eight hours of sleep each night to function at their best, getting seven hours of sleep and being in a one-hour deficit might not sound like a big deal. But if this continues for multiple days or weeks, it has a compounding effect on your health. After two weeks, you would already be in a 14-hour deficit!

Is sleep debt real? What does it do?

Because of its compounding effect, sleep debt is very real. If being in a sleep deficit is a regular thing for you, it’s not just a sense of tiredness or fatigue that is the problem. The Sleep Foundation says sleep debt can increase your risk of diabetes, stroke, heart disease and hypertension, as well as being linked to other health conditions such as reduced immunity, metabolic dysregulation, weight gain, and poor cognitive function. 

If you’re consistently getting less than 7-8 hours of sleep each night but don’t feel tired, make sure you’re paying attention to other signals your body is giving you. The Sleep Foundation says while you can adapt to fewer sleeping hours without feeling tired, declines often start to show in your physical and mental performance, and there are other metabolic signs we’ll get into shortly!

How to fix sleep debt

The occasional night of lost sleep can be repaid quite quickly by having an early night, a bit of a sleep-in, or even a nap. The Centres For Disease Control & Prevention adds that you often sleep more deeply when you’re sleep deprived, which is a helpful trick courtesy of Mother Nature herself.

But making up for multiple nights or weeks’ worth of sleep deprivation? Unfortunately, that recovery can be a lot harder, taking several nights (at least!). In this case, taking naps or sleeping in on the weekends won’t cut it either. It’s like plugging your phone charger in for 10 minutes at a time and never doing a full charge! The overall battery health will end up severely degraded.

Harvard Health has highlighted that our bodies aren’t very forgiving when it comes to changing our sleeping hours, with research showing that those who cut their sleep down by five hours during the week still pay a cost if they made up for that lost sleep over the weekend. 

We already know the serious health impacts sleep deprivation can have, but the ‘cost’ can also come in the form of increased weight, changes to how the body uses insulin, reduced energy expenditure and excess calorie consumption after dinner. And as 2019 research has shown, sleeping in on the weekend is not like hitting the ‘undo’ button to reverse those metabolic effects. 

2021 research further supported these ideas, examining the recovery process from a prolonged period of restricted sleep. When tested during the 10-day restriction period, participants displayed worse cognitive functioning. They could then sleep as often as they liked, but results showed that even a full week was not enough to restore their optimal brain function. According to additional research from 2016, one single hour of sleep debt takes four days for an individual to recover to their optimal level. Yikes.

Prevention is the best medicine

Just like vitamins aren’t a fix-it method for a poor diet, naps and weekend sleepins aren’t a bandaid for lost sleep during the week. Prevention is your best strategy if you want to reap all the health benefits of quality sleep and avoid the consequences of sleep debt.

The first step is to learn how much sleep your body needs to minimise sleep debt in the first place, says the Sleep Foundation, which the CDC refers to as the length of sleep you need to feel rested when you wake. 

If you don’t feel rested in the morning, try bringing your bedtime forward by 15-minute increments each night until you’ve found your ideal routine. If you’re in bed for 7-9 hours but not sleeping well, consider your daytime habits such as caffeine intake and timing, your exercise schedule, nap timing and stress. Harvard Health says keeping a sleep log can help to track your habits, sleep patterns and provide accountability. 

What if you’re sacrificing sleep to work out?

This is unique to you, how you’re feeling and the signs your body is giving you. As much as we applaud your commitment to your Sweat sessions, it’s best to prioritise your sleep if you’re feeling exhausted, are doing your workouts feeling sleep-deprived, or your training leaves you feeling more tired. You and your workouts will be better for it, whereas forcing yourself to exercise when you need rest will only set you back. There’s a reason we prioritise rest days in your Sweat programs and love to talk about quality sleep - it’s so important to your overall health and wellbeing!

Finally, don’t buy into the myth that sleep is for the weak or that resting is unproductive. Anyone with jetlag, a newborn baby or a looming deadline will know there are definitely seasons in life when sleep takes a backseat. But if you want to thrive in the long term and have high energy for whatever your days (and workouts) throw at you, sleep needs to be a top priority!