Sleep Deprivation: What Happens When You Don’t Sleep?

photo of a tired woman suffering from sleep deprivation

How often do you feel you get enough good quality sleep at night – sometimes, almost never? And if consecutive days of sleep deprivation stack up, do your mood and ability to do straightforward tasks start to waver?

As an insomniac myself, I’m well aware of the obvious short-term effects of sleep deprivation. After just one or two bad night’s sleep, I’m accused of being grumpy, life’s little worries gain a louder voice, and training hard in the gym feels more like a punishment than a passion.

But what else is going on behind the scenes when I don’t sleep well? Are obesity, diabetes or heart problems waiting for me later in life?

Will the flow of this article be a tsunami of thoughts rather than the gentle stream of carefully crafted words that I’d like it to be? Perhaps you can be the judge of that as I explore what sleep researchers have to say about sleep deprivation in this article.

photo of a man sleeping

A growing problem

The Centers for Disease Control and Prevention (CDC) have found in their surveys that a third of American adults usually get less than the recommended amount of sleep (7 to 9 hours). And this is presumably an issue that many other nations also face.

Modern life makes it a challenge to even have enough time left for a long sleep at the end of an action-packed day. We’ve become expert jugglers of responsibilities and pastimes – work, study, childcare, activities, social events, the latest binge-worthy series or funny cat videos on social media.

Of course, not everyone intentionally sleeps less than they’d like to; from sleep disorders to ill-health to unavoidable responsibilities, the list of explanations for missing out on sleep is long.

But whatever the cause, people are at a higher risk than ever of developing symptoms and disorders related to sleep deprivation – of which there are many. So even if you feel like less sleep is unavoidable, it’s a good idea to reassess that thought from time to time.

Getting enough sleep is not a luxury—it is something people need for good health.


What is sleep deprivation?

According to the American Academy of Sleep Medicine (AASM), the definition is quite straight-forward: “Sleep deprivation occurs when an individual fails to get enough sleep”.

So it’s usually not seen as a disease or illness, rather a result of other illnesses or life circumstances. But the resulting sleep deprivation then causes other symptoms or health problems.

What causes sleep deprivation?

The specific causes of sleep deprivation are virtually endless! Some common examples include:

  • Personal obligations and responsibilities, such as caring for a child or adult.
  • Work hours – working long hours, shift work, going abroad for work, long daily commutes.
  • Choosing to spend time on other activities instead of going to bed at a reasonable hour, such as working, studying, socializing, watching TV, playing games or being online.
  • Medical problems: sleep disorders, physical or mental health conditions. Anxiety, stress, depression, pain, paranoia, for example.
  • Medication or drug usage.
  • Problems with the sleep environment, such as noise, temperature or an uncomfortable bed.

Sleep deprivation symptoms

There are some symptoms of sleep deprivation that are perhaps easier to observe in yourself or those you know well. Learning to recognize these symptoms might serve as an early-warning alarm system that you need to catch up on your sleep:

  • Feeling excessively sleepy during the day. Do you fall asleep if sitting in a quiet place, or the same place for a long time, such as at work, school or in a car?
  • Constantly yawning.
  • Sleeping through alarms.
  • Bags/darkness under the eyes.
  • Mood changes.
  • Impaired physical performance, such as coordination and athleticism.
  • Impaired cognitive performance, such as memory and decision making.

Effects of sleep deprivation

The consequences of sleep deprivation can range from mild to very serious. Below, I’ll take a closer look at some specific research studies that have shown these effects.

To start with, here’s an overview of the known effects listed by both the CDC and AASM:

Sleep deprivation effects


  • Irritability
  • Lack of motivation
  • Anxiety
  • Symptoms of depression


  • Less concentration
  • Attention deficits
  • Reduced vigilance
  • Slower reaction times
  • Distractibility
  • Lack of energy
  • Fatigue
  • Restlessness
  • Worse coordination
  • Poor decision making
  • More errors
  • Forgetfulness


  • High blood pressure
  • Heart attack
  • Obesity
  • Diabetes

Research into the effects of sleep deprivation

Let’s take a look at some interesting research studies that have unearthed what happens to us when we’re sleep deprived, either on a short-term or long-term basis.

1. Increased anxiety

Researchers at the University of California studied the effect of sleep deprivation on the anxiety levels of 18 volunteers. They were tested after a normal night’s sleep, and again after staying awake after 24 hours.

After 24 hours with no sleep, people experienced a 30% increase in anxiety levels. Interestingly, the researchers also found that those who had longer periods of non-REM deep sleep showed the lowest anxiety and emotional reactivity levels.

This led the author to describe deep sleep as a “nocturnal soothing balm, taking the sharp edges off our lives”.

photo of an anxious woman biting her nails

2. Increased anger and bad mood

Researchers at Iowa State University enrolled the help of 142 people to see how sleep might affect their anger levels.

They found that after two days of restricted sleep, the participants reported feeling more anger and worse mood due to factors such as noise while completing tasks.

Researchers back in 2012 also found that sleep deprivation increases anger, stress, and anxiety. In their study, they manipulated the stress levels of tasks the 53 volunteers had to do.

Interestingly, both the well-rested and sleep-deprived suffered during the high-stress condition. But only the sleep-deprived people became more angry, stressed and anxious in the low-stress condition.

3. More errors related to memory

Researchers in 2018 tested the ability of 234 volunteers to complete a task with regular interruptions. The idea being that they had to repeatedly remember where they were in the task and successfully carry on.

They then either had a good night’s sleep or were kept awake in the lab for 24 hours, before returning to the task.

They found that the sleep-deprived group made more errors, and that errors relating to memory failure increased the longer they spent on the task.

4. Increased risk of chronic disease

Researchers are still trying to fully understand the exact relationship between sleep and a number of health conditions. The CDC lists the current examples of high blood pressure, type 2 diabetes, cardiovascular disease and obesity.

A number of studies have been done which appear to indicate that sleep is important for maintaining good health where these conditions are concerned.

Researchers at the University of Chicago found that more and better sleep could be a key way to improve blood sugar control in people with type 2 diabetes.

photo of a woman testing for diabetes

Researchers at Tennessee State University state that obstructive sleep apnea is associated with coronary heart disease, heart failure, and cardiac arrhythmias.

And as researchers point out, there is plenty of evidence that sleep is related to obesity. And although the exact mechanism is still being explored, it’s suggested that sleep impacts metabolism and appetite.

As they summarize:

There is now enough evidence that sleep could have an effect on energy balance. The precise mechanisms for this are currently under investigation. Sleep is probably not the only answer to the obesity pandemic, but its effect should be taken seriously, as even small changes in energy balance are beneficial.

S Taheri

5. Higher risk of accidents, including when driving

There are many jobs that require a person to be as alert and focused as possible, such as surgeons, dentists, and pilots. But there are also times when we all need to be in good shape, such as when driving.

Perhaps unsurprisingly, research into road traffic accidents has shown that being sleep deprived increases the risk of having an accident when driving.

In a review of crashes involving 6845 culpable and non-culpable drivers, Brian C Tefft looked at their self-reported hours of sleep in the 24 hours before crashing.

He calculated that the odds of being found culpable increased as people got less than the recommended 7 to 9 hours sleep:

  • 1.3 times more likely to be culpable with 6 hours of sleep.
  • 1.9 times more likely with 5 hours.
  • 2.9 times more likely with 4 hours.
  • 15.1 times more likely with less than 4 hours.
photo of a tired man yawning while driving a car

6. Less likeable and sociable

In recent years, a number of fascinating studies have looked at how sleep deprivation influences both how lonely or sociable we feel, as well as how others perceive us. And the results so far don’t look good for the chronically sleep deprived!

It’s known that loneliness has a damaging effect on people – we are social creatures after all. So on a personal level, I find it worrying that researchers have found that we’re less likely to socialize when sleep deprived.

In their study, the researchers found that people pressed a button on a video to stop someone walking towards them sooner than when not sleep deprived. They had less activity in brain regions associated with socializing, and more in areas that are active when we feel our personal space is being invaded.

Moreover, they then showed videos of the participants to other people, who said they were less to socialize with the people who looked tired and lonely themselves.

As the study authors say:

…a lack of sleep—both total sleep deprivation and more modest, real-world reductions in sleep quality—leads to a behavioral profile of social withdrawal and loneliness. 

Simon & Walker
photo of people socializing at a party

7. Behavioral problems in children

If you’re a parent, you’ll probably know that children rarely behave at their best when they become too tired.

A team of researchers analyzed 86 studies involving a total of 35,936 children, in an attempt to summarize what a lack of sleep does to school-age children (5 to 12 years in their research).

And while they didn’t find that sleep loss affected their memory like it does adults, they did find it led to an increase in behavioral problems and worse performance in school.

Sleep deprivation treatment

The good news is that most of the effects of sleep deprivation can be reversed when you finally get more sleep. But it might take a concerted effort to keep sleep deprivation, and some of the hidden problems it brings, at bay in the long run.

For me personally, the best treatment for sleep deprivation has always been to make sure I allow plenty of time for sleep.

It might seem like a fantasy if you have an incredibly busy schedule or a condition that affects your sleep. But I think it’s a good starting point: make sleep a priority and don’t let other activities swallow your needed sleep time.

And regardless of individual circumstances, it’s important to practice good sleep hygiene to get the most out of the time spent in bed. Some good techniques are:

  • Stick to a regular sleep schedule.
  • Only use the bedroom for sleep.
  • Avoid caffeine, alcohol and sugary drinks in the afternoon and evening.
  • Avoid heavy meals in the 2-3 hours before bed.
  • Make your bedroom cool, dark and quiet, with a big enough bed and comfortable bedding.
  • Don’t use electronic devices in bed.
  • Do something relaxing before bed, such as stretching, reading, meditation, yoga.
  • Exercise regularly, but not intense exercise shortly before bed.

And if you have an ongoing problem with your sleep, it’s a good idea to talk to your primary care doctor about it. They can assess if there’s an underlying cause and hopefully treat it. They can also refer you to a sleep specialist or therapist if they think it might be helpful.

Final thoughts

As I said at the start, I know that losing sleep doesn’t do me much good, to say the least. But research shows that there are perhaps more worrying consequences of poor sleep that build over time.

I can cope with being a bit absent-minded or grumpy for a day or two. But knowing that I’m more at risk of accidents or developing heart conditions definitely makes me want to put even more effort into my sleep than I already do.

I might write about sleep, but it doesn’t mean I’m the best sleeper! So I hope this article will do a little to inspire both you and I to give sleep the attention it deserves.

Your view

Do you get enough sleep, or is sleep deprivation an ever-present and frustrating part of your life? Feel free to share your story and thoughts about how it affects you in the comments below.

10 thoughts on “Sleep Deprivation: What Happens When You Don’t Sleep?”

  1. I spent everyday doing homework, working past midnight. I think it’s because of assignements when it comes to reading. I am a slow reader and this takes a lot of my time. What can I do? How do I get eneough sleep?

    1. Hi Ana
      Thanks for your comment. I would do two things – first, set yourself a limit for your study time to ensure you get enough sleep. If that means you can’t complete the assignments, then talk to your family, teacher or tutor to see if you can get some additional support with that. They may be able to find a way to help you improve your reading speed, if it is something that needs to improve.

  2. I haven’t slept well in 5 years. Nothing helps. I have thyroid disease, fibromyalgia and was misdiagnosed with the thyroid and forced on Abilify for 3 years. I gained over 40, became very physically ill. And now I can’t sleep.
    2 years off of the stuff and I think the Abilify is what did this to me. Any help??? Now I’m psychotic?

    1. Hi Laira
      Thanks for your comment. Goodness, that sounds very unfortunate…what does your doctor say about your current sleep problems? Do you talk to them about it, and ask if any of your medical conditions or treatment could be causing it?

  3. hey
    I’m a student of standard tenth. In order to study well with some entertainment, I am regularly unable to manage my time and my everyday sleep consistS of hardly 6 hours. Therefore I feel tired after a few hours work and get irritated easily. Day by day I am becoming aggressive. Is there a solution?

    1. Hi Ekta
      I think the only solution is to make more time for sleep. It’s an important part of having a good sleep routine that you decide in yourself that sleep is an important part of your day, and not something to be sacrificed.
      And if you think study is more important than getting a long night’s sleep, have a read of this article. It talks about research that shows students perform worse on less sleep, even if they stay up to study! So you might find less late night study and more sleep means better results.

  4. I once had an insomnia episode that lasted six weeks. I slept around 3/4 very very bad hours at night and some nights I didn’t sleep at all. On week 6 I got a prescription for bromazepan and that got me out of that state. I was completely altered and I couldn’t perform at work or exercise or even social interaction in the end. I really wasn’t myself, it was terrible. That was a year ago and I haven’t had anything close to that but I always have the pills just in case and I do take them ocasionally. I feel psychologically dependant to them since they got me out of that terrible state. I would love to be free of them someday. Thank you for this page, it feels really good to know there are people that go through the same!

    1. Hi Emma
      Thanks for your comment. I’m glad you found the article helpful and reassuring to know that you’re not alone. I think what you describe is quite common – people often find something helps them sleep, and so are reluctant to completely let that thing out of their sight as a back-up plan. I’ve done the same myself with herbal remedies – just knowing I have them if I need them somehow makes me relax a bit more and sleep better. I guess it depends how often you take them. Perhaps you can try to slowly wean yourself off by attempting other things first rather than taking them if you hit a difficult patch. Try out all the good sleep habits that help people generally, and in time you should be able to tackle your sleep naturally without needing the pills again, hopefully!

  5. Hello Ethan!

    I am a recovering insomniac (trying to be positive here. Besides, it comes and goes…mostly just comes). And I have suffered from the effects of sleep deprivation. One time when I was a freshman at the university, I went for 52 hours without sleep. It was hard to feel the effects after the first 40 hours because I was on a road-trip, the constant partying kinda got in the way of any negative effects. But later, my head was foggy, everything was in slow motion and it felt like my head was underwater… the sounds were so muffled. But after a total blackout of about 11 hours I was cool.
    I’ve also had hallucinations because of lack of sleep. This one actually scared me and that’s when I decided to take affirmative action against insomnia. I was almost talking to a face that appeared on my cardigan in class!
    Thank you so much for sharing this. I needed this as I’m currently only getting 4 hours of sleep every night. I might have to make some serious changes in lifestyle. Thanks again Ethan.

    1. Hi Joanne
      Thanks for your comment, and I’m glad you found the article helpful. 4 hours probably isn’t enough sleep on an on-going basis, so it sounds like some lifestyle changes might help. Sometimes the slow build up of sleep deprivation can go more unnoticed than in more extreme situations like your 52 hours. You’ll probably find that if you give yourself more time to sleep, life will be better!

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