What Is Sleep Deprivation and How Does It Affect You?

Quick Answer: Sleep deprivation happens when you get less sleep than your body needs. It may leave you sleepy, groggy, irritable, or struggling to concentrate after just one short night. When sleep loss continues, it can affect memory, judgment, reaction time, mood, metabolism, immune function, and cardiovascular health.

Have you ever woken up feeling like you barely slept at all? Your head feels heavy, you may have a headache, and even small things seem to get on your nerves more than usual. By the afternoon, keeping your eyes open or concentrating on something simple can take more effort than it should.

Missing sleep once in a while happens to almost everyone. But sleep can also get cut short night after night because of work, family responsibilities, stress, health problems, or simply staying up later than you planned. When you regularly get less sleep than your body needs, you are dealing with sleep deprivation.

How you feel afterward can depend on how much sleep you missed, how long it has been happening, and what is keeping you from sleeping in the first place.

What counts as sleep deprivation?

You do not have to stay awake all night to be sleep-deprived. Sleep deprivation happens when you do not get enough sleep for your body's needs. It may last for a night or two or continue over a much longer period. 

Sleep deprivation can be partial or total:

• Partial sleep deprivation means you still sleep, but you get less than you need.

• Total sleep deprivation means you stay awake continuously without sleeping.

Partial sleep deprivation is much more common in everyday life. Someone who needs about eight hours but regularly gets only five or six hours can still experience the effects of sleep loss, even though they sleep every night. (1)

Also Read: Why Sleep is Important for Your Health

How much sleep do you need?

Most healthy adults need at least seven hours of sleep each night, though the exact amount varies from person to person. Many adults do best with seven to nine hours, and more sleep may be appropriate when recovering from illness or after several nights of missed sleep.

Your daytime functioning can also give you clues about whether you are getting enough sleep. If you regularly struggle to stay awake, have difficulty concentrating, or sleep much longer on days off, your usual sleep schedule may not be meeting your needs. 

Getting enough hours matters, but so does the quality of those hours. Repeated awakenings, sleep apnea, pain, or another health condition that disrupts your sleep can leave you feeling tired even if you spend enough time in bed.

How can you tell if you are sleep-deprived?

Feeling sleepy is usually the easiest sign to notice, but it is not the only one.

You may experience:

• Daytime sleepiness

• Feeling tired or groggy after waking (brain fog)

• Headaches

• Irritability or stronger emotional reactions

• Difficulty concentrating

• Forgetfulness

• Trouble solving problems or making decisions

• Slower reaction time

• More mistakes than usual

Sleep loss can make everyday tasks noticeably harder. You may find yourself rereading the same paragraph several times, forgetting what someone just told you, losing track of a conversation, or taking longer to finish something that is normally part of your routine. 

When sleepiness becomes strong enough, microsleeps can occur. These are brief, involuntary episodes of sleep that can happen without you realizing you have fallen asleep. Even a few seconds of lost attention can be dangerous when you are driving, operating machinery, or doing anything that requires you to stay focused. 

Also Read: Biphasic Sleep: Is Sleeping Twice a Day Healthy?

Why aren't you getting enough sleep?

There are plenty of reasons sleep gets pushed aside. Work runs late. A baby wakes you throughout the night. You stay up watching another episode or scrolling longer than you meant to, then find yourself hitting snooze a few times the next morning because you still don’t feel ready to get up. 

In other cases, you already make enough time for sleep, but something keeps interrupting it.

Common causes include:

• Work or school schedules. Long hours, early starts, studying, commuting, or working more than one job can leave too little time for sleep.

• Shift work. Overnight and rotating schedules can make sleeping difficult because your work hours may conflict with your usual sleep-wake cycle.

• Family responsibilities. Caring for children, older parents, or another family member can shorten sleep or interrupt it repeatedly.

• Stress and mental health. Stress, anxiety, depression, and PTSD may interfere with falling asleep or staying asleep.

• Sleep disorders. Insomnia, sleep apnea, restless legs syndrome, and circadian rhythm disorders can all disrupt sleep.

• Pain and other health problems. Acid reflux, breathing problems, frequent nighttime urination, pain, and illness may repeatedly wake you up.

• Medications. Some prescription and OTC medications have side effects that can make it harder to fall asleep or to stay asleep.

• Caffeine, nicotine, and alcohol. Caffeine and nicotine can keep you awake, while alcohol may make sleep lighter and more fragmented later in the night.

• Your sleep environment. Noise, light, temperature, or frequent disturbances can reduce the amount of uninterrupted sleep you get. 

Going to bed earlier may help when bedtime keeps getting pushed back. It will not fix repeated breathing interruptions from sleep apnea or pain that wakes you several times a night. That is why the cause matters when deciding what to do next.

Also Read: What Is Short Sleeper Syndrome and How Do You Know If You Have It?

What are the stages of sleep deprivation?

The stages of sleep deprivation usually refer to total sleep deprivation, when someone stays awake continuously. They are different from the effects of sleeping an hour or two less than usual.

People may experience these effects at different times, but symptoms generally become more severe the longer someone goes without sleep. 

These changes do not happen at exactly the same time for everyone, but research shows a similar pattern. After about 24 to 48 hours without sleep, people may become more anxious, irritable, confused, or notice changes in what they see or hear. As sleep loss continues, hallucinations and more serious problems with thinking can occur, while delusions become more likely after around three days. (2)

What can long-term sleep deprivation do to your health?

Headaches, irritability, and grogginess can happen after just one poor night, but the long-term health risks of sleep deprivation are linked to regularly getting too little sleep.

Mood and mental health

Persistent sleep deficiency has been linked to depression and changes in emotional regulation. Poor sleep can also make it harder to cope with stress or regulate emotions, especially when sleep loss persists over time. 

Heart and blood pressure

Regularly sleeping too little is associated with a higher risk of high blood pressure, heart disease, and stroke. These associations are seen with ongoing insufficient sleep rather than an occasional short night. 

Appetite, blood sugar, and weight

Sleep affects hormones that regulate hunger and fullness, as well as how the body responds to insulin.

When sleep is consistently too short, changes in appetite and glucose regulation may make weight loss more difficult. Regularly not getting enough sleep is also associated with obesity and type 2 diabetes. 

Immune function

Not getting enough sleep can also affect the body's ability to respond to germs and illness. Regularly sleeping less than recommended has been associated with an impaired immune system. 

How sleep deprivation differs from sleep deficiency, insomnia, and sleep debt

Sleep deprivation is often confused with sleep deficiency, insomnia, and sleep debt. The difference comes down to whether you are not getting enough sleep, cannot sleep despite having the opportunity, or have been accumulating missed sleep over several nights.

Imagine two people who both slept only five hours.

One stayed up until 2 AM finishing work before getting up at 7 AM. There simply was not enough time available for sleep. The other went to bed at 10 PM but remained awake for hours despite trying to sleep.

Both may be sleep-deprived the next day, but the second person may also be experiencing insomnia. 

Sleep debt develops when those short nights keep adding up. If your body needs eight hours and you repeatedly sleep six, the difference accumulates over time. 

Can you get used to sleeping less?

You can get used to feeling tired, but that does not mean you have adapted to getting less sleep.

In a 2021 study, adults who were limited to five hours in bed for several nights showed worsening attention. Some still felt relatively alert even when their performance had declined. (3)

Over time, sleeping less can start to feel normal even while it is still affecting how well you function during the day.

How long does it take to recover from sleep deprivation?

Recovery depends on how much sleep you lost and how long you have been sleeping too little.

After one short night, getting enough sleep again may help you feel much better. But if you have been getting too little sleep for several nights, recovery can take longer, and some effects may improve faster than others.

Sleeping longer on your days off may reduce some of the sleepiness that builds up during the week, but one weekend does not necessarily make up for regularly missing sleep. Big differences between weekday and weekend schedules can also shift your circadian rhythm, or internal body clock.

Naps can improve alertness for a while, but they do not provide all the benefits of regular nighttime sleep. 

What can help if you aren't getting enough sleep?

Start by identifying what is taking sleep away from you. If bedtime keeps getting later, making more room for sleep may be enough. If you already spend plenty of time in bed but still struggle to fall asleep, wake repeatedly, or feel exhausted the next day, another problem may need attention.

Depending on what is interfering with your sleep, these changes may help:

• Protect enough time for sleep. Work backward from when you need to wake up instead of letting bedtime keep moving later.

• Keep your schedule reasonably consistent. Going to bed and waking up at the same time each day can make your sleep-wake cycle easier to maintain.

• Move caffeine earlier. Caffeine can continue affecting you for hours after you drink it.

• Pay attention to repeated awakenings. Snoring, gasping, pain, acid reflux, restless legs, or frequent bathroom trips may warrant discussion with a healthcare provider.

• Review medications that may affect sleep. Ask your healthcare provider or pharmacist if your sleep changed after starting a prescription or OTC  medicine rather than stopping it on your own.

• Make daytime sleep easier if you work nights. Keeping your room dark, quiet, and comfortable, and avoiding frequent changes in shift timing when possible, may help.

• Get persistent insomnia treated. Cognitive behavioral therapy for insomnia, or CBT-I, is commonly recommended as a first treatment for long-term insomnia. 

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When should you talk with a healthcare provider?

Consider talking with a healthcare provider if poor or insufficient sleep keeps happening despite making enough time for rest, especially when sleepiness begins affecting work, school, driving, or everyday activities.

It is also worth getting checked if you:

• Regularly have difficulty falling asleep or staying asleep

• Wake up tired despite spending enough time in bed

• Fall asleep unintentionally during the day

• Experience frequent microsleeps

• Snore loudly or wake up gasping for air

• Have persistent difficulty adapting to shift work

• Feel too sleepy to drive safely

Keeping a sleep diary for a couple of weeks can make an appointment more useful. Record when you go to bed and wake up, how often you wake during the night, any naps, and how sleepy or rested you feel during the day.

If you are struggling to stay awake behind the wheel, stop driving and find somewhere safe to rest. Microsleeps can occur before you realize you have fallen asleep, and a few seconds of lost attention can be enough to cause an accident. 

About the author

Dr. Ruchir P. Patel, MD, FACP, is the Medical Director of the Insomnia and Sleep Institute of Arizona and the founder of Sip2Sleep. He is triple board-certified in sleep medicine, obesity medicine, and internal medicine. Dr. Patel is a multi-year Phoenix Magazine Top Doctor and holds the Inspire Excellence designation.

Reference

1. Van Dongen, H. P., Maislin, G., Mullington, J. M., Dinges, D. F., & New Collective Author (2003). The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation. Sleep, 26(2), 117–126. https://doi.org/10.1093/sleep/26.2.117

2. Waters, F., Chiu, V., Atkinson, A., & Blom, J. D. (2018). Severe Sleep Deprivation Causes Hallucinations and a Gradual Progression Toward Psychosis With Increasing Time Awake. Frontiers in psychiatry, 9, 303. https://doi.org/10.3389/fpsyt.2018.00303

3. Mathew, G. M., Strayer, S. M., Bailey, D. S., Buzzell, K., Ness, K. M., Schade, M. M., Nahmod, N. G., Buxton, O. M., & Chang, A. M. (2021). Changes in Subjective Motivation and Effort During Sleep Restriction Moderate Interindividual Differences in Attentional Performance in Healthy Young Men. Nature and science of sleep, 13, 1117–1136. https://doi.org/10.2147/NSS.S294409

4. Amin F, Sankari A. Sleep Insufficiency. [Updated 2023 Jul 25]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK585109/