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What causes nightmares: bad dream

The question “why do we have nightmares” is more common than can you imagine. At some point in our lives, we’ve all experienced this unpleasant phenomenon. However, while some of you are having nightmares only from time to time, others suffer from this experience every night. 

In this guide, I’ll answer the question “what causes nightmares”, provide you with the symptoms, and the ways to stop bad dreams. Thus, if you want to find out what causes bad dreams, continue reading. 

Sue Peacock

Consultant Health Psychologist

Can nightmares be dangerous to the human's mind/health?

Nightmares become much more than bad dreams when they have a significant effect on your health and well-being. Among people who experience nightmares, those who are anxious or depressed are more likely to be distressed about the experience and suffer even more psychological ill effects.

Causes Nightmares: Introduction

Nightmares are also called bad dreams that can cause strong emotional feelings, such as anxiety, fear, despair or sadness. Psychologists often highlight that bad dreams are not the same as nightmares.

The main difference is that nightmares tend to wake you up from sleep, however, during bad dreams individuals usually stay asleep. What is more, nightmares tend to be more vivid than bad dreams, and you can usually remember all the details when you wake up. 

Nightmares, just like any other dream, tend to appear during the REM stage of sleep, usually, in the second half of the night. Before moving further, let me shortly explain to you how our sleep cycle works to make all the further aspects of what causes nightmares clear. 

The sleep cycle can be explained as a fluctuation between NREM and REM stages of sleep. During stage 1, you experience the transition between being awake and light sleep. Stage 2 leads to more sleep and it gets more difficult to wake you up. 

What causes nightmares: bad dream

Stage 3 is also known as a deep sleep stage. It’s crucially important to all mental and physical processes as then our body restores itself. During stage 3 the growth hormone is released, that’s why it’s also vital for children and teenagers. 

Needless to say, after these 3 stages, you get into REM sleep, when you experience the most vivid and memorable dreams. It starts after about 90 minutes after you fall asleep. The sleep cycle tends to last from 90 to 120 minutes. The first cycle is usually the shortest and others tend to get longer. 

Moving further, very little is known about why we dream, however, a few theories exist. One of them[1] claims that dreaming improves our cognitive capacities, in other words, it enhances our imagination.

What is more, the theory by Revonsuo proposes that dreams allow us to reverse and prepare for real-life threats, which is an evolutionary advantage. Moreover, many studies[2] believe that dreaming is beneficial for our memory processes. 

Therefore, while the knowledge gap about why we’re dreaming exists, there are many theories that can explain it logically.


Even though it seems quite obvious when you’re having a bad dream, many people do not know the difference between nightmares and night terrors. 

What causes nightmares: nightmare

Nightmares might appear not once but multiple times during the session of sleep at any age. Night terrors, on the other hand, are more common in children and tend to disappear when they age. 

Here are the main symptoms of nightmares: 

  • You can remember your dreams clearly when you wake up.
  • In the nightmare, you often feel a threat to your life.
  • Everything is so vivid that you can easily mistake it for reality. 
  • After waking up from a nightmare, you might find it difficult to fall back asleep. 
  • You wake up feeling anxious, scared and sad. 
  • Sweating and pounding heart after waking up from the dream.

Even though the majority of us experience nightmares from time to time, it can be called a nightmare disorder[3] only if this phenomenon occurs frequently and negatively affect your work, ability to concentrate, lead to problems with memory, daytime drowsiness and even fear of going to sleep. 

Causes of Nightmares: What’s Behind Them?

It’s time to answer the question “what causes nightmares?” You’ll see that there so much more conceivable causes than you imagined. 

Anxiety and Stress 

Stress and anxiety are usually the most common causes of nightmares. Even though stress is often “invisible”, it can have a major impact on your sleep and dreams. Simple things such as new tasks at work, increased responsibilities, moving to the new place (even though it should cause happiness and exoticness), and many other daily activities can lead to higher levels of stress. 

You may have noticed that before huge events you’re experiencing nightly disruptions. So, even if you feel calm, the dreams can reveal whether or not you’re experiencing psychological issues, such as anxiety and stress. 

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Traumas are widely connected with stress. One of the characteristic features of posttraumatic stress disorder is nightmares. According to Ali A El-Solh[4], the professor of medicine: “While the majority of individuals afflicted with PTSD experience sleep dysfunction, the prevalence of posttraumatic nightmares in patients with PTSD can be as high as 72%.”. 

Additionally, the University of Pittsburgh School of Medicine study found that about 80% of people who are suffering from PTSD are experiencing frequent nightmares. 

So, if you have recently experienced trauma, lost a loved one or someone you care about suffering from serious illnesses, PTSD might be what causes nightmares and interrupts your sleep. Based on the data, about 70-80% of people with PTSD experience this issue. 

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Individuals who suffer from depression are not only interested in what causes nightmares but also what could improve the quality of their sleep and how to fall asleep faster. 

What causes nightmares: depression

It’s known that depression is widely linked to sleep. Since depressed people tend to be pessimistic, they experience dreams with a negative mood and emotion. This can be the answer to the question “why do I keep having nightmares?”. 

Moreover, since depressed individuals often think about ending their lives, it’s natural that they experience more dreams related to death. 

BMC Psychiatry performed a study[5] to investigate if depression is linked to sleep disturbances and trauma-related nightmares. The results showed that about two-thirds (65%) of individuals who suffer from depression were experiencing sleep disturbances, and 88% of them were suffering from nightmares. 

Therefore even though there are many possible answers to the question “what causes nightmares?”, if you’ve been feeling depressed recently, then this might be the answer. In case you’re feeling this way, you should contact your doctor without hesitation. 

Sleep Deprivation

Sleep deprivation is strongly linked to nightmares, however, it’s usually not the cause but the result of bad dreams. People who suffer from severe nightmare disorder, tend to associate sleep with having bad dreams. As a result, they find it difficult to fall asleep because they’re constantly thinking about what awaits. 

This problem is quite difficult to overcome as “what causes nightmares” and sleep deprivation are strongly related. 


If you’re a fan of scary movies, then the answer to what causes nightmares can be pretty simple. Many studies suggest that people, especially children, who like watching scary movies tend to experience bad dreams. 

Even though each of our minds reacts differently to horror movies, the majority of people who watch such films before going to sleep should prepare for nightly disruptions. 

Your Environment

It’s important to make yourself comfortable when going to sleep. That includes not only the room temperature but also a mattress that you’re sleeping on. 

You should make sure that your room temperature is not too high and not too low, the best room temperature is considered 65° F since your body temperature decreases once you fall asleep. Also, my advice is to get some fresh air into your room. 

What causes nightmares: bedroom

There’s an interesting study that I would like to introduce you to. Boris Stuck that specializes in adult and pediatric otolaryngology wanted to see if the smell has an impact on people’s sleep. For that, he found 15 volunteers and used the smell of rotten eggs and roses. 

Once the volunteers fell asleep and reached the REM/dreaming stage, they released those smells. The results indicated that individuals who were smelling roses had more pleasant dreams, while those who were exposed to the rotten eggs smell, experienced more disturbing dreams and even nightmares. 

Talking about a mattress, it’s important to make the right choice and pick the alternative based on your personal needs. If you want a more conforming alternative, then memory foam mattress is a good option, however, if you prefer it to be more bouncy and supportive, then it’s recommended to pick either innerspring or latex bed. 

So, even though it seems that the answer to the question “what causes nightmares?” is only psychological, your room environment can also have a great impact. 

Drugs and Medication

Based on Psychology Today, drugs that are taken to enhance the function of serotonin (chemical and neurotransmitter) or norepinephrine (hormone and neurotransmitter) neurons, also, drugs that impair the function of acetylcholine (neurotransmitter) neurons, and medicine that relieves anxiety, and creates drowsiness are all what causes nightmares. 

What causes nightmares: medicine

What is more, alcohol consumption is also known to create disruptions in your dreams and lead to unpleasant bad dreams. 

All things considered, it seems that we all should be experiencing nightmares, even though it’s only one of the possible answers to the question “what causes nightmares?”

Eating Before Sleep

If you’re used to eating right before going to sleep, then you shouldn’t be asking “why do I keep having nightmares?”. Since junk food is associated with nightmares, if you’re used to snacking before bed, make sure its a healthy snack, such as carrots, eggs, pumpkin seeds and so on. 

On the other hand, if you find it quite easy to break this habit, then you should try to avoid eating at least 3-4 hours before going to sleep not to cause any indigestion. 

How to Stop Nightmares

By now you know what causes bad dreams, however, there are always ways to solve this problem. 

Dealing with Stress

Even if you had a stressful day at work, you should know how to relax at the end of the day. The most popular and known to be working stress-relieving techniques are yoga, relaxing music, reading a book before going to sleep, a warm bath, especially with a few drops of essential oils such as lavender or valerian. 

Maintaining Good Sleep Environment

If you want to help yourself relax and fall asleep faster, you should turn out all the light sources at least 30 minutes before going to sleep. Also, make sure to allow some air into your room. 

Since sleeping too hot or too cold might also be the reason behind “why do I keep having nightmares?”, you should set your bedroom temperature at about 65° F - it’s known to be the perfect temperature for sleeping.

Also, make sure you’re sleeping comfortably. If you wake up with soreness in your neck, spine, and shoulders, then it might indicate it’s time to get a new mattress. If you want to find the best-evaluated options, you can check them out here. 

Write it Out

If your work is constant stress and you have no idea how to stop it, then you should either visit a doctor or write your emotions out. Many psychologists believe that writing down your nightmares or talking about them with a therapist can help you relax. 

What causes nightmares: bad dreams

If you wake up in the middle of the night, shaken by the experience, take a piece of paper and write down all you remember while also changing the course of your dreams. Even though this technique is not for everyone, it’s definitely worth giving a try.

Visit a Doctor

We often play doctors and once something happens “Google“ the problem to find out all the answers. In other words, we often diagnose ourselves. However, you should stop doing this and finally visit a doctor - he/she will find a problem and offer possible solutions to your issues. 

Needless to say, we tend to exaggerate the problem, even if the issue can be easily fixable. 


Therefore, even though the answer to the question “what causes nightmares” is individual for each of you, we can make certain assumptions based on the causes of bad dreams, including:

  • Anxiety and stress
  • Depression
  • Trauma
  • Sleep deprivation
  • Media (scary movies)
  • Environment
  • Drugs and medication
  • Sleeping before bed 

Even though it’s not so easy to stop nightmares, there are certain methods that can help. At first, deal with the stress practicing meditation, yoga, reading a book, listening to calm music. Then, make sure to maintain a good sleep environment, a comfortable mattress is not an exception. 

What is more, you should consult a specialist who will help you find the answer to the question “why do we have nightmares?” and how you can deal with them. Finally, try to write down all the details you remember from your dreams - some people say that this technique is working. 

Sue Peacock

Consultant Health Psychologist

Contributed By Sue Peacock, Consultant Health Psychologist

Dr. Sue Peacock is a leading Consultant Health Psychologist registered with the Health and Care Professions Council. She is an Associate Fellow of The British Psychological Society and a Registered...

Read Full Bio...

Scientific References

Contributed by Sue Peacock, Consultant Health Psychologist

1. Michael S. Franklin, Michael J. Zyphur: 'The Role of Dreams in the Evolution of the Human Mind '

2. Björn Rasch and Jan Born: 'About Sleep's Role in Memory'

3. Annika Gieselmann, Malik Ait Aoudia, et al.: 'Aetiology and treatment of nightmare disorder: State of the art and future perspectives'

4. Ali A El-Solh: 'Management of nightmares in patients with posttraumatic stress disorder: current perspectives'

5. Don Richardson J, King L, St Cyr K: 'Depression and the relationship between sleep disturbances, nightmares, and suicidal ideation in treatment-seeking Canadian Armed Forces members and veterans.'

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Recent User Reviews

sleep lamp

when I bought sleep lamp it fixed all my problems with the nightmares

Over thinking

I’m having insomnia, and then once i sleep i wake up 2 or 3 hours later because of a nightmare, i think it’s caused by my insomnia.

I’ll visit a doctor

It’s been three months now, since i’m having nightmares, three or four times per week, it’s a lot, i never had such issues before!


The more I think about sleep disturbances the more anxious I get. I appreciate the advice, writing down what bothers me seems like something I would do.

should use these tips

should use these tips



Great article

Very valuable information, i hope it will help people out there who have nightmares.

Need to sleep better

Love this website, I feel I'm getting all the inspiration I need. Since I don't sleep well, I have bad nightmares, sometimes I have to start my day at 4am, I have to do something about it.

Stress is definitely a cause

I’ve noticed that i’m always having more nightmared during my stressful exam periods, so yes, i think stress is a major cause.

scary movies

I never watch scary movies because I can't sleep after them.

So much things to improve

I’m used to eat before sleeping, and to never care about my room’s environment, i guess that why the quality of my sleep is so poor.

Want to stop them

Nights have become my least favorite thing, I fall asleep and have horrible dreams, it's all since covid started I feel very stressed, but maybe when this ends nightmares will go away as well

very good article

very good article

How to deal with stress

As a student i dont see how i’ll deal with stress, i’ve exams almost everyday and i dont have time to relax, so i dont know how.


I went straight to the psychological side of nightmares - for a while - honestly it was just a sign of me sleeping really bad, my mattress was hard and I woke up in pain every morning. After I solved this, nightmares and pain are gone.

Finding my cure

Been dreaming that someone is chasing me, I wake up in the middle of the night almost shouting which wouldn't be so bad if I didn't have a roomie! Reading all your tips. ?

Room environment

I’ve always said that to my children, i think it’s a must not only to avoid bad dreams, but to have a healthy sleeping in general.


Whenever I have a nightmare I think it's something absolutely random. Is it because something I smelled or ate? Time to find out!


I moved to my new apartment and want to say goodbye to the bad sleeping nights and nightmares. Got fancy sheets, comforter sets, I'm ready!

fat food

I know that I have lots of nighmares when I eat a lot of fat food before bedtime


What can cause bad dreams?

There are many factors that can cause bad dreams, including trauma, depression, sleep deprivation , stress and anxiety, drugs and alcohol, scary movies, unpleasant sleeping environment, and even junk food before sleep.

How do I stop having nightmares?

There are several ways to stop nightmares. You can try different relaxation techniques, such as meditation, yoga, listening to relaxing music or reading a book. What is more, make sure to settle a pleasant and comfortable sleeping environment - you can try essential oils for sleep. Also, stick to healthy eating habits and create a routine.

What is a memory foam mattress?

Memory foam mattresses are created mostly from polyurethane and have additional chemicals added that increase its viscosity and density. It’s also often called “viscoelastic polyurethane foam”. In order to create the air movement and let your body “breath” while you sleep, it has open foam bubbles. Memory foam mattresses are created in a way to adapt to your body curves and to also recover their original shape after you get up. Therefore, this kind of top mattresses offer you the feeling as if is created specifically for you.

Do top rated mattresses offer a money-back guarantee? Is there a catch?

All of the top mattress brands offer a money-back guarantee. The free trial usually starts from 90 to 100 nights, and if you don’t like the mattress, you can simply give it back. The majority of best mattress providers will not only give your money back but will also come to get it for free. If the mattress provider is reputable, there won’t be any catch - everyone understands that you have to try the mattress before knowing if it fits you.

What is off-gassing? Is it poisonous?

Off-gassing refers to the odor which comes from a new mattress. It’s the process that happens when volatile organic chemicals (VOCs) leak out of the mattress foam into the air. Those chemicals include both human-made and natural components, including formaldehyde, chlorofluorocarbons (CFCs), benzene, trichloroethane, and perfluorocarbons. Top rated mattresses will have zero or very minimal off-gassing. Many of them are sent to the customer already after the off-gassing. Is it dangerous, though? Even though the smell can be unpleasant, there’s usually only a very small amount of chemicals that can do no harm to your health.

How long do top rated mattresses serve?

The durability of a mattress depends on the provider and the quality of the materials used. Usually, you get a 10-year warranty, which will be valid in case of any defects. Normally, mattresses will serve you from 7 to 10 years, or even longer. Thus, when you buy the best mattress, you should take it as a long-term investment.