Why Do We Have Nightmares and How Common Are They?

A woman sitting up in bed awoken by a nightmare.

Written by: Gabrielle Talan

Gabrielle, a former insomniac turned sleep writer, brings over a decade of content expertise to her work. For the past 3 years, she's focused exclusively on sleep topics – a happy choice that helps give her the deep and restful sleep she craves.

Have you ever woken up from a nightmare so scary or disturbing that it leaves you unsettled for a good-sized chunk of your day? You're not alone, because nightmares are a common occurrence for most people. However, in some cases, they're more than just bad dreams and can hint at an underlying health issue.


If you're concerned about the bad dreams you're experiencing, the first step is to gain a better understanding of nightmares. Read this article to learn what they are, why they occur, how to prevent them from happening, plus the most common nightmares and their symbolic meanings.

Key Takeaways

  • Nightmares are common, affecting both adults and children. The probable causes of nightmares include stress, anxiety, post-traumatic stress disorder (PTSD), certain medications, sleep disorders, sleep deprivation, caffeine, alcohol and certain foods.

  • Frequent nightmares, especially when they have developed into a nightmare disorder, can significantly harm sleep and your day-to-day life. Frequent and highly distressing nightmares can indicate an underlying health issue.

  • Ways to reduce nightmares include practicing good sleep hygiene, managing stress through relaxation techniques, imagery rehearsal therapy, and seeking professional help when nightmares persist.

Table of Contents

What Are Nightmares?

Nightmares are vivid or intense dreams that cause the dreamer to wake up feeling scared, sad or anxious. They typically occur during rapid eye movement (REM) sleep, the sleep stage in which most vivid dreams occur.


You shouldn't confuse nightmares with night terrors, which occur during the first few hours after falling asleep. They involve intense behavior, such as screaming, kicking or thrashing during sleep. People who experience night terrors have no memory of them when they wake up.

How Common Are Nightmares?

Nightmares are very common, with up to 70% of the general population experiencing them occasionally and 2% to 5% of the adult population having them frequently, according to a study published in the Journal of Clinical Sleep Medicine.(1)


Nightmares are more common in children. According to Harvard Medical School, nightmares especially affect children aged 3 to 6.(2) Kids that fall in this age range are particularly susceptible to nightmares because their brains are still developing and their imaginations are highly active. However, they typically grow out of them, and nightmares decrease in frequency as they age.

Why Do We Have Nightmares?

Nightmares happen due to several factors, including stress and anxiety, post-traumatic stress disorder (PTSD), some medications, other sleep disorders, sleep deprivation, caffeine, alcohol and certain foods.


Let's explore each cause in more detail.

Stress and Anxiety

Stress and anxiety can cause nightmares because they affect how the brain processes emotions during sleep. As we mentioned earlier, dreams typically occur during REM sleep. This sleep stage is when the brain is very active, and the most vivid dreams take place. Also, the brain is more focused on emotions and memories than on rational thought. When a person is extremely stressed or anxious, it can affect their dream content, potentially making dreams scarier or more disturbing and turning them into nightmares.


People suffering from stress or anxiety usually experience racing thoughts or ruminate before bedtime. Sometimes, these negative thoughts and emotions carry over into sleep as the brain attempts to process them, causing nightmares.


Another way stress and anxiety can cause nightmares is that they can disrupt sleep, interfering with your sleep cycle. This fragments sleep and affects the brain's ability to process and regulate emotions, leading to nightmares.

PTSD

Post-traumatic stress disorder is a mental health disorder that can lead to nightmares as a result of the brain trying to process traumatic events.


The emotions and memories associated with traumatic events can become ingrained in a person's psyche. The brain processes these emotions and memories during REM sleep, typically resulting in vivid, disturbing nightmares. These types of nightmares can be a replay of the traumatic event; they can even present themselves as recurring nightmares, but not always.


PTSD is associated with hyperarousal and anxiety, which can worsen nightmares, becoming a vicious cycle. PTSD in itself requires treatment and therapy. Getting professional help can reduce how often and intensely PTSD-related nightmares occur.

Certain Drugs and Medications

Certain types of drugs can cause nightmares as a side effect. Let's take a look at the most common ones:


  • Antidepressants, such as selective serotonin reuptake inhibitors (SSRIs), can increase serotonin levels, which can affect sleep and dreams.

  • Medicine that treats high blood pressure and heart problems, like beta-blockers and antihypertensives, can disrupt sleep and cause nightmares.

  • Statins, which are used to treat high cholesterol, have been reported to cause nightmares in some individuals.

  • Ironically, certain sedatives used to treat sleeplessness, like benzodiazepines, can cause nightmares, most especially when use is suddenly discontinued.

  • Some antibiotics, like fluoroquinolones, have been linked to nightmares.

  • Steroids for reducing inflammation may also lead to vivid dreams and nightmares.


If you are experiencing nightmares on any of these medications, consult your healthcare provider for other options.

Other Sleep Disorders

Several sleep disorders have been linked to nightmares, including sleep apnea, narcolepsy, restless legs syndrome (RLS) and insomnia.


  • Sleep apnea is a sleep disorder characterized by pauses in breathing caused by blocked airways during sleep. It can increase the likelihood of nightmares by stressing your body and disrupting sleep.

  • Narcolepsy causes you to fall asleep uncontrollably during the day and disrupts your sleep at night. This can lead to more vivid dreams and sometimes nightmares.

  • RLS is a sleep disorder characterized by an uncontrollable urge to move your limbs during sleep. It can also cause discomfort. These symptoms can fragment sleep patterns that increase the likelihood of nightmares.

  • Insomnia is when you have difficulty falling and staying asleep. This can lead to stress and anxiety, which may trigger nightmares. It works the other way around, too, when stress and anxiety cause sleep deprivation, which can also increase your risk of nightmares.


Speaking of disorders, there is one that is tied explicitly to bad dreams.


Nightmare disorder is when someone experiences frequent nightmares that consistently disrupt sleep and cause a lot of distress. This disorder can affect your day-to-day. You might feel tired, anxious or scared of going to sleep, which is known as sleep anxiety.


People with nightmare disorder usually remember their dreams when they wake up, and may have difficulty falling back to sleep. This disorder warrants professional help because it can have a huge impact on your mental health and well-being.


Consult a healthcare provider if your nightmares persist or are affecting your daytime functioning.

Sleep Deprivation

We mentioned earlier that sleep deprivation can ramp up stress and anxiety levels, leading to nightmares. Another way it can cause nightmares is by interfering with the body's sleep architecture, especially affecting the REM sleep stage, where vivid dreams often occur.


When the body finally gets the sleep it needs, the brain enters what is called "REM rebound," which entails an unusually long and more intense period of REM sleep. Its duration and intensity can lead to more vivid dreams, including nightmares.

Caffeine and Alcohol

Caffeine is considered a stimulant, meaning it makes you feel more awake and alert. Consuming caffeine too close to bedtime can prevent you from falling asleep, which harms your sleep quality. It also disrupts REM and other deep sleep stages, where dreaming often takes place. This disruption fragments your sleep, increasing the chances of having nightmares.


Many people believe that consuming alcohol can lead to falling asleep faster. While this is often true, it also disrupts your sleep by causing multiple awakenings at night. As the sedative effect of alcohol wears off, it fragments your sleep and prevents you from entering the REM sleep stage in the first few hours of sleep. This results in an REM rebound, which you already know can lead to intense and vivid nightmares.

Eating Certain Foods Before Bed

Eating certain foods before bed has been associated with an increased risk of nightmares. These include spicy foods, sugary foods, fatty foods and caffeine. A study published in Frontiers in Psychology found that 31% of survey participants reported sweets and desserts as leading to nightmares, while 22% attributed nightmares to dairy products.(3)


Let's explore how each type of food can contribute to nightmares:


  • Spicy foods raise body temperature and can cause indigestion, disrupting sleep and increasing the likelihood of nightmares.

  • Sugary foods can cause the body's blood sugar levels to spike and crash, which can cause sleep to be restless, leading to nightmares.

  • Fatty foods take longer to digest and can cause indigestion or discomfort, disrupting your sleep cycle and making nightmares more likely.

  • Caffeine prevents you from falling asleep and also disrupts REM sleep, which can lead to nightmares.


Knowing what to eat and what not to eat before bedtime doesn't just prevent nightmares, but also ensures you get high-quality sleep, helping you function properly during the day.

What Are the Most Common Nightmares?

A woman having a nightmare that she’s falling.

While many nightmares are unique, certain dream themes are common. They are also often the subjects of recurring dreams. Here are some of the most common nightmare themes and their possible meanings.

Falling

Having a nightmare where you're falling is one of the most common themes. It represents losing control or fearing that you'll fail in your waking life. Usually, people wake up before they hit the ground.

Being Late

Dreaming of being late usually indicates stress and anxiety about deadlines or other responsibilities. It is also associated with a fear of failure.

Being Chased

When you dream that someone or something is chasing you, it means you are stressed, anxious, or threatened in real life. Whatever is chasing you, be it human, animal or something else, symbolizes what is threatening you.

Being Naked in Public

Experiencing a nightmare of being naked in public represents feeling vulnerable or a fear of being exposed in your waking life.

Death of a Loved One

Dreaming of the death of a loved one (or even your own death) can represent a fear of losing something, change or the unknown.

Drowning

Having a nightmare about drowning can mean that you're feeling overwhelmed in your waking life. It may also indicate a loss of control. You might be anxious about things in your life, such as responsibilities, emotions or situations that are too much to handle.

Losing Your Teeth

Dreaming of losing your teeth can mean several things. One is that you might be experiencing miscommunication with someone in your life. Another is a fear of aging or concerns about how you look.

How to Stop Having Nightmares

There are several ways you can stop having bad dreams. Some of them involve lifestyle changes, others involve certain techniques and getting professional help, especially when the cause of your nightmares is linked to trauma.


  • Practice good sleep hygiene: This involves sticking to a consistent sleep schedule, establishing a relaxing bedtime routine, and creating a sleep environment that's cool, quiet and dark by using accessories like sleep masks. Establishing good sleep habits goes a long way if you want to alleviate nightmares and get better sleep.

  • Stress Management: You already know that stress and anxiety are major triggers for nightmares. Consider trying relaxation techniques, such as progressive muscle relaxation or breathing exercises. Engage in relaxing activities before bed, such as yoga, meditation or reading a book. You can also write down the stressful thoughts of the day by keeping a night journal.

  • Try imagery rehearsal therapy: This type of therapy involves changing the story of your nightmare to make it less frightening by writing it down when awake, then rehearsing it until you get fewer bad dreams.

  • Get professional help: Occasional nightmares are normal. However, if your distressing dreams persist and affect your daily life, they may indicate a deeper problem, so it's essential to consult an expert.

Conclusion

Occasional nightmares are common, and they affect both adults and children. They're often caused by factors like stress, anxiety, PTSD, certain medications, sleep disorders, sleep deprivation, caffeine, alcohol, and specific foods.


You can lessen the frequency of nightmares by practicing good sleep hygiene, managing stress, and trying techniques like image rehearsal therapy. An effective way to reduce your nightmares is to improve your sleep quality.


While occasional nightmares are normal, frequent or distressing ones can harm your overall health and well-being. If lifestyle changes and IRT don't work, then it's time to seek professional help.


Do you have any tips you'd like to share with other readers on managing nightmares? Leave a comment below.

Frequently Asked Questions About the Causes of Nightmares

Can Horror Movies or Games Cause Nightmares?

Yes, horror movies or games can cause nightmares by causing stress and anxiety, which can trigger bad dreams.

Why Do I Get Nightmares When I’m Sick or Have a Fever?

You get nightmares when you're sick or have a fever because your body temperature heightens, which can disrupt and fragment your sleep. This disruption may result in more vivid and intense dreams, including nightmares.

Can Stress or Anxiety Cause Nightmares?

Yes, stress and anxiety can cause nightmares. They can impair your brain's ability to process memories and experiences during sleep, especially during REM sleep, when vivid dreaming usually occurs. Being stressed or anxious can also spill over into your dreams, making them frightening or disturbing.


Stress and anxiety can also make it difficult to fall asleep and stay asleep, impacting your sleep quality and causing sleep disruptions, which increases the likelihood of having nightmares.

Why Do I Keep Having the Same Nightmare?

You keep having the same nightmare because your brain may be attempting to process anxiety, stress or trauma that hasn't been addressed in your waking life. You may continue having the same dream until the stressor is resolved. It's your brain's way of processing difficult emotions or experiences.

Why Do My Nightmares Feel So Real?

Your nightmares feel so real because they usually occur during the REM sleep stage, when your brain is highly active and more focused on emotions and feelings than logical thinking. This may make your nightmares vivid and emotionally charged, tricking you into thinking they're happening in real life.

Why Do I Keep Having the Same Nightmare Over and Over?

You keep having the same dream over and over because your brain is attempting to process unresolved stress, anxiety or trauma. If these remain unresolved in your waking life, you may experience recurring nightmares.

Sources:  

(1) "A Systematic Review of Cognitive-Behavioral Treatment for Nightmares: Toward a Well-Established Treatment.” Journal of Clinical Sleep Medicine, jcsm.aasm.org/doi/10.5664/jcsm.27285. Accessed 19 December 2025.

(2) “Nightmares and the Brain.” Harvard Medical School, hms.harvard.edu/news-events/publications-archive/brain/nightmares-brain. Accessed 19 December 2025.

(3) “More dreams of the rarebit fiend: food sensitivity and dietary correlates of sleep and dreaming.” Frontiers in Psychology, www.frontiersin.org/journals/psychology/articles/10.3389/fpsyg.2025.1544475/full. Accessed 22 December 2025.


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