When's the last time you felt like you had the energy to seize the day? If you, like many others, can't answer the question immediately, chances are you're struggling with a sleep deficit.
Having a sleep deficit feels a lot like being in debt the financial way; you're down in the dumps and stressed out. Arguably, a sleep deficit may be even more pernicious than racking up credit card bills. After all, sleep is as essential as air, food, and water.
But what exactly constitutes a sleep deficit? Is there a way to compute it without complicated numbers and formulas? Most importantly, if you're mired in sleep deprivation, is there any repayment plan for it? Keep reading for the answers to all your pressing questions.
Disclaimer: This post is meant for informational purposes only and should not replace medical advice from a healthcare professional. While the RISE app is designed to support natural sleep and boost sleep hygiene to address symptoms of sleep deprivation, it does not treat medical conditions such as sleep disorders.
Many of us are keenly aware of what a personal monetary deficit entails: your spending exceeds your income. In a similar line of thought, sleep deficit occurs when your sleep duration falls short of your sleep need. We call it sleep debt in the RISE app.
Before we go into the nitty-gritty of sleep debt, let's first talk about your sleep need, which is genetically determined just like your eye color or height. Rather than the generalized "eight hours of sleep per night" recommendation, your individual sleep need likely lies between 7.5 and 9 hours. And around 13% of the general population needs nine hours of sleep or longer each night to feel and function at their best during the daytime.
When you don't meet your sleep need, you aren't getting enough sleep and are racking up a sleep deficit, or sleep debt. This can be categorized into two stages:
If you identify as chronically sleep-deprived, it's almost a certainty that you're grappling with acute sleep debt, too.
The urge to fall back to sleep when your alarm clock rings in the morning is completely normal, and it’s a phenomenon scientists termed sleep inertia. The occasional yawn during your afternoon dip when your circadian rhythm (aka the internal body clock) hits an energy trough is also normal. The same goes for the few hours before bed as your body slows down in anticipation of sleep.
But outside of these natural and expected energy dips, if you feel even the tiniest bit sleepy during the day, that's a sign of a sleep deficit. As William Dement, one of the pioneers in the field of sleep medicine, constantly preached, "Drowsiness is red alert."
If you think you're sufficiently rested, chances are it's the exact opposite. We tend to underestimate our sleep need and overestimate our sleep duration. Most insidiously, we subjectively adapt to our sleep deficit, even though we objectively decline across all aspects of cognition, emotion, and physiology.
Even if you start to make an effort to get the amount of sleep your sleep-deprived body needs, you may continue to hamstring your daytime functioning. This is because you're simply doing the bare minimum of meeting your sleep need rather than recouping lost sleep. So while you might not be falling further into debt (which is a step in the right direction), you aren’t yet repaying the debt you’ve already accumulated (more on this later).
Anyone who's suffered from sleep loss before (read: almost everyone) is no stranger to how sleep debt holds you back from life. To understand how a sleep deficit is the proverbial “ball and chain” dragging your feet, you first need to learn about sleep homeostasis.
You can picture the sleep homeostat as a seesaw that wants to be balanced. During your waking moments, adenosine (aka sleep pressure) builds up in your brain. The burgeoning sleep pressure tilts the seesaw to one side, throwing it into disequilibrium. When you sleep, your brain purges the accumulated adenosine and rebalances the sleep homeostat.
What if you don't meet your sleep need? Insufficient sleep means your brain doesn't have enough time for the full adenosine purge. As a result, your system is still suffused with leftover adenosine when you wake up the next day. This vicious cycle continues — and compounds the problem — for as long as sleep restriction persists.
The repercussions of a short sleep duration are alarming, to say the least. Because the recycle rate of the human brain is roughly 16 hours, staying awake longer than that equates to low-level brain damage. In fact, a 2021 study from Ohio State highlighted that sleep loss mimics symptoms of a concussion.
More studies on a lack of sleep portray a similar, if not equally scary, narrative. Going 18 hours without sleep causes cognitive impairment on the same level as a blood alcohol concentration (BAC) of 0.05%. Skipping out on sleep for 24 hours straight worsens your cognitive impairment to the degree of someone with a BAC of 0.10%, higher than every state’s legal limit.
Shockingly, you don’t need to pull an all-nighter to experience these effects. Let's say you’ve only slept seven hours for 10 consecutive nights (read: one hour less than the eight that is just under the average need). Your brain is now as impaired as if you’ve pulled an all-nighter.
Accruing sleep debt in the short term handicaps everything you do right off the bat. Case in point: increased daytime sleepiness, impaired cognition, slower reaction times, a weakened immune system, and a poorer mood the next day.
On top of that, you're now more susceptible to various health problems in the long run. Think heart disease, weight gain and obesity, Type 2 diabetes, high blood pressure, mental health disorders, and even cancer. Most worryingly, research based on fruit flies unearthed a direct relationship between sleep loss and early death.
Indeed, the short- and long-term effects of sleep deprivation are nothing to sneeze at.
The good news is, you can evade having a sleep deficit by tracking how much sleep you get. Note that we're talking about the quantity of sleep rather than the "quality of sleep" that so many sleep-tracking apps harp on.
That's because there is no such metric as "quality sleep" (at least for now). It's mind-blowing, we know. But the fact remains that sleep scientists have yet to agree on an objective definition for this subjective parameter of sleep.
Of paramount importance, not many people — or apps — take into account that the human brain already self-optimizes sleep. This is a good thing since you can't consciously manipulate the amount of time you spend in each stage of your sleep cycle, be it rapid eye movement (REM) sleep or non-REM sleep. (Although sleep-detracting activities like ill-timed caffeine consumption or alcoholic drinks certainly stymie your brain's naturalistic processes for healthy sleep.)
That's why sleep-tracking apps that overemphasize your sleep patterns last night are merely offering up superfluous information that has no bearing on your well-being and performance today.
So, which sleep score should you focus on to optimize your daytime functioning? You guessed right — sleep debt.
A tool like the RISE app helps you accurately — and effortlessly — track your sleep debt, so you can extricate yourself from a sleep deficit. Your sleep debt score on the Sleep screen of the app is easy to understand and immediately actionable to help you regain control of your sleep and life.
How RISE calculates your running sleep debt:
As you can see, the app is intuitively simple to use and an effective way to track your sleep times. You never have to struggle with hard-to-understand scientific jargon or feel at a loss on how your sleep data can help achieve better sleep for better days.
So, can you dig your way out of a sleep deficit? The answer, for the most part, is yes.
There are two levers to bring down sleep debt to less than five hours, the gold standard for feeling and functioning at your best during your waking moments. These two levers, as proposed by Alexander Borbély in his two-process model of sleep, are:
You can bring down your sky-high sleep debt via healthy sleep hygiene (see next section). But can you actually bounce back from acute sleep debt and chronic sleep deprivation?
The canonical sleep study on the topic of repaying back sleep debt from the University of Pennsylvania School of Medicine shows that recovering from acute sleep debt is indeed possible. To do so, you need to outsleep your sleep need, not just meet it. So, if your sleep need is 8.5 hours, you will need to get extra sleep for the next night (or more), depending on how much sleep debt you're saddled with.
The science on writing off a chronic sleep deficit is more ambiguous. Still, even if you're chronically sleep-deprived, making a dent in your acute sleep debt will be to your advantage. You can hit the sheets earlier each night, nap during your afternoon dip, or sleep in up to an hour as a last resort — as waking up more than an hour later than your usual rise time can throw your internal clock off-balance, inciting circadian misalignment.
Because you have a 14-day window to work with when it comes to paying down acute sleep debt, give yourself some leeway. Just like how one full night of sleep won't miraculously dissolve your debt, one bad night won't tank things either.
If your sleep deficit isn't egregiously high, you can choose to wait until the bad nights are no longer part of the 14-day count before restarting on a clean slate.
Have trouble keeping it all in your head? The RISE app makes it visually effortless to track your sleep debt over the next two weeks, as seen on your Progress screen.
Sleep hygiene is the upkeep of behaviors that influence the way you sleep. That is to say, it isn't merely about healthy sleep habits in the moments before bed. Good sleep hygiene should take place 24/7.
But optimal sleep hygiene only comes into existence when it's tied to your circadian rhythm, so you know when to carry out sleep-promoting actions, like daytime naps and caffeine cut-offs. Because everyone's internal clock is genetically unique, a tool like RISE takes the guesswork out of playing nice with your circadian rhythm. Your Energy Schedule in the app tells you the exact timing of your energy peaks and dips each day.
Now, we've made it even easier to work with your daily energy fluctuations to feel and function at your best with our newest feature — the RISE Calendar Integration. See your daily energy alongside your schedule to align your energy and activities. Visit your profile — in the latest version of the RISE app — to connect your calendar.
We are no strangers to sleep problems, especially since the Centers for Disease Control and Prevention (CDC) has declared insufficient sleep a “public health epidemic.” Needless to say, surviving on less sleep than you need is the fast track to sabotaging your life in all the ways that matter.
But the good news is, you can get back in the black with the RISE app. It focuses on the two things well within your control — paying down sleep debt and working with your circadian rhythm — to have you feeling your best as soon as you can. And we have the statistics to back up our claim: 80% of our users feel the benefits in as short as five days.
With RISE, the days of a good night's sleep are just around the corner to help you be at your best when you need to — physically, mentally, and emotionally.
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