The Two Sleep Deprivation Stages: Acute and Chronic

Keep reading to understand the ill effects of both acute and chronic sleep deprivation as well as how you can turn back the clock on acute sleep loss.

Coping, struggling, suffering, losing it. Though hardly a scientific classification of sleep deprivation stages, those words in that order paint a picture of what it can feel like as hours of sleep loss begin to add up over days or weeks. 

Taking into account the low energy, cognitive decline, and medical problems associated with sleep deprivation — the effects of mounting sleep loss are alarming. The good news? It is possible to catch up on sleep.

In this article, we’ll explore the differences between acute sleep deprivation and chronic sleep deprivation and explain how the RISE app can help you adopt better sleep hygiene habits to reduce your sleep debt and increase your daytime energy levels. 

Sleep Deprivation Can Feel Like Torture

From irritability to extreme exhaustion, being deprived of sleep brings its own kind of misery. Used as a form of torture as far back as 17th century England, sleep deprivation was one of the "enhanced interrogation techniques" used at Guantanamo Bay starting in 2003. Detainees would commonly experience cognitive impairment followed by slurred speech and sometimes hallucinations and paranoia.

But why does lack of sleep wreak such havoc and misery? It seems to be something akin to inadequate waste removal.  In 2013, Dr. Maiken Nedergaard and her team at the University of Rochester Medical Center discovered a system that drains waste products from the brain.They named it the glymphatic system. It’s a cleanup system that’s most active during sleep and uses cerebrospinal fluid to flush away toxic byproducts that accumulate between cells. 

The longer you go without sleep, the more these waste products pile up, and the lousier you feel. Perhaps that’s why sleep loss is sometimes considered to be a kind of low-level brain damage. A recent study from Ohio State found that sleep loss resembles symptoms of a concussion

Sleep Deprivation by the Hour

The longer you’re awake, the more intense and serious the negative impacts of sleep deprivation get. Here is a breakdown of the symptoms of sleep deprivation by the hour. (It’s worth noting that you don’t have to go long periods without sleep. Gradual sleep deprivation over multiple nights can cause similar impairment and damage. More on this later.)

After 16 Hours Without Sleep

In his book, Why We Sleep, Matthew Walker explains, ”the recycle rate" of the human brain is around 16 hours. Stay up past that, and your brain is no longer working optimally. It’s becoming an overflowing trash can. And after 18 hours without sleep, you’ll suffer the same level of cognitive impairment as a person with a blood alcohol level (BAC) of 0.05%. 

After 24 Hours Without Sleep

It’s almost impossible to feel and perform at your best the day after pulling an all-nighter. In fact, going 24 hours without sleep results in cognitive impairment equivalent to having a BAC of 0.10%, higher than the legal limit for driving in all 50 states.

After 36 Hours Without Sleep

A 1997 study found that 36 hours of wakefulness can reduce attention span, slow reaction time, and increase the occurrence of microsleeps — brief, involuntary episodes of unconsciousness.

After 48 Hours Without Sleep

Staying awake for two days straight not only makes you more prone to accidents, it also significantly weakens your immune system, as the body experiences a drop in natural killer cells that have antiviral and anti-tumor properties. 

After 72 Hours Without Sleep

If you don’t sleep for 72 hours, in addition to overwhelming sleepiness, you’ll likely experience heightened anxiety and possibly even delusions and hallucinations.

Acute and Chronic Sleep Debt: The Two Sleep Deprivation Stages

Effects of Sleep Deprivation

Because real life isn’t a timed series of extended sleep deprivation experiments, it’s helpful to use the concept of sleep debt as a way to measure and classify sleep loss. The only two stages of sleep deprivation that should really concern you are acute sleep debt and chronic sleep debt. 

Acute Sleep Debt 

Acute or short-term sleep debt is the running total of the hours of sleep you missed — as compared to the sleep your body needed — over the past 14 days. Because it’s the number that best predicts how you’ll feel and function on any given day, acute sleep debt is the focus of the RISE app. We recommend keeping your sleep debt under five hours in order to feel and function at or near your best.

You don’t have to pull an all-nighter to feel the effects of sleep deprivation. For example, if you miss meeting your sleep need by just one hour per night, after 10 days you’ll be just as impaired as you would be if you’d been awake for 24 consecutive hours.

Maybe you think it’s no big deal to stay up for a couple of hours past your bedtime to watch a new movie on Netflix, but when an hour or two of lost sleep here and there starts to pile up, you’ll suffer the consequences. Acute sleep debt comes with a host of implications across every aspect of health and performance.

The Effects of Acute Sleep Debt

  • Daytime sleepiness and fatigue
  • Decreased attention span, focus, and productivity
  • A weakened immune system
  • Increased moodiness, irritability, and impatience
  • Changes to your metabolism including increased appetite
  • Increased risk of accidents

Chronic Sleep Debt

Sleep deprivation is a widespread problem with serious adverse health and social consequences, and the Centers for Disease Control and Prevention (CDC) has declared insufficient sleep a “public health epidemic.” 

Studies show that chronic sleep debt — when you go for years or decades rarely meeting your sleep need, let alone paying any of the debt back  — can have deleterious health effects, including increased susceptibility to chronic disease and other medical conditions.

The Effects of Chronic Sleep Debt

  • Greater risk for weight gain, obesity, and Type 2 diabetes 
  • Increased risk of  high blood pressure, cardiovascular disease/heart disease, and heart attack
  • Higher risk of cancers, such as colorectal cancer and breast cancer
  • More susceptible to psychiatric disorders, fertility problems, and other health problems

So, is the end state of sleep deprivation death? It certainly looks that way. Considering the serious ailments that become far more inevitable or are otherwise exacerbated by chronic sleep deprivation, it’s not surprising that years of getting less sleep than your body needs can hasten your demise. Recent research with fruit flies suggests a direct link between sleep deprivation and death.

But you don't actually have to die from sleep deprivation for it to feel like you're dying from sleep deprivation. Taking into account the extreme discomfort and cognitive decline caused by acute sleep deprivation and the serious health problems associated with chronic sleep deprivation, you might be ready to make getting enough sleep a top priority. 

But how can you know for sure if you have high sleep debt?

How to Tell If Your Sleep Debt Is Too High

Sleep deprivation stages: RiseApp My sleep
The RISE app automatically calculates and keeps track of your sleep debt for you.

As humans, we’re not the best at judging whether or not we’re sleep deprived. That’s because we have a natural ability to adapt subjectively  to insufficient sleep. After just a few nights of sleep loss, you may think you’re doing fine, but all the while, you’re actually in decline across almost every measure that matters.  

So, how do you know if you’re suffering from acute sleep debt? The RISE app will tell you. Rather than getting into the gray area of trying to define or rate so-called “quality sleep,” or analyzing the different stages of sleep  — deep sleep vs. rapid eye movement or REM sleep, for example — the RISE app focuses on the amount of sleep you’re getting, which is to say, whether or not you’re meeting your genetically-determined sleep need. 

Using data from your phone, along with sleep-science-based models, the app learns your genetically driven sleep biology to calculate your sleep need in hours and minutes. From there, the app automatically calculates and keeps track of your 14-day sleep debt number for you. 

Because it’s not realistic to expect total sleep perfection all the time, we recommend keeping your sleep debt under five hours. At that level, you can still feel good and perform at or near your best. 

But what happens if your sleep debt number starts to creep up? Can you pay it down? 

It Is Possible to Pay Down Sleep Debt 

Acute sleep debt is reversible. In one study, participants who had their sleep restricted to 4.5 hours per night for a full week subsequently experienced a dramatic improvement in cognitive performance and mood after getting just two full nights of recovery sleep. 

Unfortunately, the research on recovering from chronic or long-term sleep debt is less conclusive. According to the National Institutes of Health, scientists and sleep experts have doubts about the body’s ability to recover completely from the serious health consequences associated with chronic sleep deprivation. 

But even if you can’t totally reverse the effects of chronic sleep deprivation, making a real effort to reduce your acute sleep debt is definitely worthwhile. It doesn’t take long to start feeling the benefits of lowering your sleep debt; most RISE users feel the benefits within five days..

How to Reduce Your Sleep Debt

To reverse acute sleep deprivation, you either have to outsleep your sleep need until you pay down your sleep debt or let the clock run out on the 14 days by meeting your sleep need every single night. 

Although keeping a consistent sleep schedule is an important part of a healthy sleep routine, if your sleep debt is high, making small adjustments here and there can help you get out of debt. You might go to bed a little bit earlier or squeeze in afternoon naps when you can. As a last resort, you can sleep in a little later than normal. Pushing your wake time is better than high sleep debt, but keep in mind that extreme shifts can disrupt your body’s circadian rhythm. 

Your circadian rhythm is an internal body clock that governs your natural sleep-wake cycle and other predictable energy fluctuations in roughly 24-hour periods. Maintaining circadian alignment with good sleep hygiene and healthy sleep habits can help you keep your sleep debt low. 

Good Sleep Hygiene — Your Secret Weapon 

Sleep deprivation stages: person running outdoors

Sleep hygiene is the upkeep of behaviors that affect the way you sleep. To optimize your daily habits for a good night’s sleep and better next-day energy levels, follow these guidelines. 

Time Your Light Just Right

Your circadian rhythm is heavily influenced by the sunrise-to-sunset cycle. Ideally, you want to expose yourself to light — preferably sunlight — first thing in the morning to signal your brain to stop producing melatonin, a sleep-inducing hormone. (Going for a walk or a run during your morning sun time is even better, as physical activity during the day can help you sleep better at night.) 

In the evening, you should avoid light — especially blue light and bright light — in the 90 minutes before bed to help support and maximize your body’s melatonin production. A pair of blue-light blocking glasses can help. 

Avoid Caffeine, Alcohol, and Large Meals Later in the Day/Night

Because they are known sleep disruptors, don’t consume caffeine in the 10 hours before bed, big meals in the three hours before bed, or alcoholic beverages in the 3-4 hours before bed. The RISE app will remind you of these cutoff times. 

Make Bedtime a Matter of Routine 

Your circadian rhythm thrives on consistency, so keep a regular bedtime and wake time that allows you to meet your sleep need. And make sure you set aside time to disconnect from the stress of the day before you go to sleep. Schedule a nightly wind-down period to do some light reading, take a warm bath or shower, meditate, or sip a cup of decaf tea.

Optimize Your Bedroom for Sleep

The perfect sleep environment is cool, dark, and quiet. Set your thermostat at 65-68 degrees, and try to keep your room completely dark. Light disrupts your body’s natural melatonin production, so use blackout curtains or blinds and an eye mask. And because ambient sounds can disturb your sleep and cause nocturnal awakenings, use a white noise machine and earplugs.

Seek Medical Help If Needed

If you practice stellar sleep hygiene but are still unable to get the sleep you need, talk to your doctor or a sleep specialist. A sleep study and other tests can help determine if an underlying medical condition, sleep apnea, or another sleep disorder could be part of the problem. 

Measuring Sleep Deprivation Stages With Sleep Debt

Although it may be interesting to look at the effects of sleep deprivation after 24, 48, and 72 hours of staying awake, breaking it down in terms of sleep debt is far more useful. When you know how much sleep debt you have, you know exactly how much sleep you need to get in order to keep or lower your sleep debt to less than five hours. 

With the RISE app, all of the calculations are automatic. There are no extra steps to take to keep up with your progress. Not having to worry about or even see the fancy algorithms and all the data gathering going on behind the screen lets you focus on what’s most important — getting the right amount of sleep at night so you can have the energy you need during the day.

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About Rise
Rise is the only app that unlocks the real-world benefits of better sleep.

Instead of just promising a better night, we use 100 years of sleep science to help you pay down sleep debt and take advantage of your circadian rhythm to be your best.

Over the past decade, we've helped professional athletes, startups, and Fortune 500s improve their sleep to measurably win more in the real-world scenarios that matter most.

Rise Science is backed by True Ventures, Freestyle Capital, and High Alpha; investors behind category winners Fitbit, Peloton, and Salesforce Marketing Cloud.
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