How Sleep Deprivation Affects the Human Body

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The effects of sleep deprivation have been well studied. Sleep deprivation happens when you do not get enough sleep, or good quality sleep, to meet your body's needs.

Not getting adequate sleep affects the whole body and is linked to many chronic health problems, including heart and kidney disease, high blood pressure, diabetes, stroke, obesity, and depression. Sleep deficiency is also linked to a higher chance of injury in adults, teens, and children.

Person in bed with pillow over their face
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How Sleep Deprivation Happens

Sleep deprivation occurs when you get less sleep than your body needs to function. You can be sleep-deprived in the short term, as in the day after you've slept poorly (acute), or in the long term (chronic) if you are consistently unable to get enough sleep.

Sleep deprivation can happen in one night or over weeks, months, or even years.

How Much Sleep Do I Need?

According to the Centers for Disease Control and Prevention, most adults need seven to nine hours of sleep per night to feel rested. Older adults (age 65 and up) may only need seven to eight hours of sleep per night.

Not getting the sleep you need negatively affects your physical and mental health in several ways. You'll feel some of these effects right away, but others may not show up for years.

What Is Sleep Debt?

Sleep debt is the amount of sleep lost from insufficient sleep, regardless of the cause. For example, if you need eight hours of sleep to feel fully rested but only clock six hours, you have a two-hour sleep deficit for that night. This may have important health consequences as the debt builds.

Brain and Nervous System

The effects of sleep deprivation on the brain can be similar to the effects of alcohol on the brain. Research has shown that driving when sleep-deprived can be as dangerous as driving while intoxicated.

If sleep-deprived, you may notice:

  • Daytime drowsiness
  • Inability to concentrate
  • Memory problems
  • Less physical strength
  • Less ability to fight off infections

Longer periods of sleep loss may increase the risk of:

  • Depression and mental illness
  • Stroke and asthma attack
  • Potentially life-threatening concerns (i.e., car accidents, sleep apnea, and narcolepsy)
  • Hallucinations
  • Severe mood swings

Abnormal Reflexes

Other neurological reflexes are also affected by sleep deprivation. You may not have any symptoms related to these changes, but if your healthcare provider were to test your reflexes, they would be abnormal.

For example, you may have:

  • Slow (sluggish) corneal reflexes
  • Oversensitive (hyperactive) gag reflex
  • Oversensitive (hyperactive) deep tendon reflexes

Seizures

One of the most serious consequences of not getting enough sleep is that it can make you more likely to have a seizure. In addition, people who have epilepsy are at a higher risk for seizures when they are sleep-deprived.

Pain

You might be more likely to feel pain when you're sleep-deprived. Research has shown that sensitivity to heat and pressure pain is higher in people who have not had enough sleep.

Other studies have found that sleep-deprived people can be more sensitive to pain in their esophagus. That might be one reason why people get heartburn or gastroesophageal reflux disease (GERD) at night.

Sometimes, people with ongoing pain that stems from sleep deprivation are diagnosed with fibromyalgia or other chronic pain conditions.

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Hormones

Sleep deprivation can change how hormones are released by the endocrine glands. Hormones that follow a circadian pattern are the most likely to be affected by sleep.

Growth in Childhood

The effects of sleep loss or disruption in children can be a very big deal. For example, kids who don't get enough sleep may have problems with their growth.

Growth hormone is secreted during slow-wave sleep. In children, this kind of sleep is common in the early part of the night.

However, if this period of sleep is disrupted—either because a child isn't getting enough sleep or they have a condition like sleep apnea—it affects how much growth hormone gets released.

As a result, children may not reach their full growth potential. They might be shorter than they would have been if they had gotten enough growth hormone.

Thyroid Function

Sleep deprivation can also change how the thyroid gland works. Staying awake for a long time increases your energy needs. In turn, your thyroid has to work harder to keep up.

Sleep problems can also be a symptom of thyroid disorders.

Skin

Sleep is a vital component for skin repair and refinement. Getting adequate sleep affects skin surface pH, transepidermal water loss, blood flow, and skin temperature. 

Skin needs hormonal support to rebuild and stay elastic. When hormones aren't working optimally coupled with poor circulation to your tissues, dullness and a sallow appearance can result. Under-eye bags, dark circles, and wrinkles may also appear more pronounced.

Other Hormones

Some hormones are not just affected by sleep deprivation but may contribute to it. Aside from thyroid and growth hormones, other hormones that are involved in sleep include:

Imbalances in hormones are most often linked to reproductive health problems, like changes to the menstrual cycle and infertility. However, you can also have symptoms related to other body systems that rely on hormones to function.

If your sleep is affecting your hormone levels, you may have symptoms throughout your body. Many of these symptoms are common in people who are going through menopause.

Hormone-related symptoms you might experience include:

  • Hair thinning and hair loss
  • Hot flashes, sweating, night sweats
  • Cold hands and feet
  • Feeling more or less hungry/thirsty than usual
  • Nausea, constipation, and/or diarrhea
  • Headaches
  • Brain fog, depression, and anxiety

Long-Term Health Risks

Sleep deprivation can negatively affect health in both the short and long term. It can even increase the risk of dying.

The Surprising Risks of Sleep Deprevation

Risks of certain health issues can increase remarkably in correlation to lack of sleep. Sleep deprivation can cause:

  • A 36% greater risk for colorectal cancer
  • A 33% greater dementia risk
  • A 48% greater risk of developing heart disease
  • Nearly a 3X greater risk of developing type 2 diabetes
  • A 50% higher risk of developing obesity
  • A 3X greater likelihood of catching a cold

Metabolism

Not getting enough sleep can affect metabolism, which can lead to glucose intolerance and weight gain. Being overtired also makes it less likely that you'll want to take part in regular physical exercise.

High blood sugar (hyperglycemia), a common complication of diabetes, can also occur due to lack of adequate sleep over time.

Sleep deprivation can lead to insulin resistance, which is a condition where the body's cells are less responsive to insulin. Insulin resistance can lead to prediabetes and eventually type 2 diabetes if not successfully treated.

A recent systematic review concluded that adequate sleep is necessary for maintaining proper metabolic health to prevent long-term complications such as type 2 diabetes. Inflammatory markers such as CRP and SAA have been implicated in the relationship between sleep loss and glucose intolerance. Other metabolic markers such as GLP-1 and NEFA metabolism may also play a part. 

At the same time, changes in the hormones that make you feel hungry and full can happen when you haven't gotten enough sleep. Eating more and moving less can also lead to weight gain over time. These factors all increase your risk for chronic health conditions like diabetes.

Cardiovascular System

The amount of sleep you get can affect your body’s ability to heal and repair your heart and blood vessels. Those who don't experience adequate rest have an increased risk of cardiovascular disease, heart attack, and stroke.

Cancer

Researchers have started to look at whether chronic sleep deprivation may contribute to the risk of cancer. However, more research is needed to prove that there is an important link.

Dementia

Not getting enough sleep affects your brain. Over time, you might be more likely to develop memory problems and conditions like dementia. Research has suggested that the risk for dementia is especially linked to not getting enough sleep in middle age.

Immunity

There is some evidence that sleep deprivation harms immune function. A lowered immune function makes illness more likely and frequent and lengthens recovery times.

Can You Die From Sleep Deprivation?

There have been cases of people who died from being completely deprived of sleep, but most of them had a rare condition that causes severe insomnia.

Not getting enough sleep is unlikely to cause death directly. However, it can increase your risk of dying from other causes.

Being sleep-deprived can make you more likely to be injured while working, exercising, or even just going about your daily routine.

Summary

Sleep deprivation can have serious consequences for both physical and mental health. It's important to figure out how many hours of sleep you need per night to feel rested and take steps to meet that goal.

Hormones and sleep deprivation are linked. The production of some hormones, like those made by the thyroid, can be impacted by inadequate sleep, while hormones like cortisol and progesterone can contribute to sleep deprivation.

Over time, not getting enough sleep can increase your risk of chronic health conditions and might even raise your risk of dying.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading
Brandon Peters, M.D.

By Brandon Peters, MD
Dr. Peters is a board-certified neurologist and sleep medicine specialist and is a fellow of the American Academy of Sleep Medicine.