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What Causes Nightmares & Bad Dreams?

Nightmares are defined as highly unpleasant dreams that often provoke an uncomfortable emotional response within the brain. Common emotional responses include feelings of: fear, terror, horror, and depression. Some nightmares can be so intense that a person wakes up in a pool of sweat or with a rapid, pounding heart. In other cases, a person may end up crying as a result of their “bad dream” long after they’ve been awake.

Experiencing nightmares every once in awhile is relatively common. Dreams are considered to be of highly-random nature, and aren’t generally able to be controlled. For a majority of the general population, nightmares are experienced on a relatively infrequent basis. However, individuals that are constantly plagued by nightmares may want to identify some of the potential causes and work towards decreasing the frequency, intensity, and/or their emotional response to the nightmares.

What causes nightmares and bad dreams?

In many cases it is difficult to pinpoint specific causes of nightmares. Many people believe that they are simply due to random nature of dreams, however there could be a variety of factors that influence whether someone has nightmares and/or bad dreams. It is important to understand that what may cause one individual to have nightmares may not be the same in another – we are all different.

  • Anxiety: People with high levels of anxiety may be more prone to nightmares than average. There tends to be a correlation between high stress levels and nightmares. Individuals who suffer from an anxiety disorder or those who are naturally anxious may be more likely to have bad dreams.
  • Brain activation: For some people, activation of certain parts of the brain may make them more prone to experiencing bad dreams. For example, someone who is highly stressed may exhibit significant activation in certain parts of the brain that they wouldn’t have had they been relaxed. Therefore, it can be thought that activation of certain regions may lead to nightmares.
  • Brain injury: People that have endured significant brain injuries may be at risk for a variety of conditions. Although everyone is affected differently based on the specific site of their injury as well as the damage, most injuries are associated with negative effects. One particular result may be that a person has poorer sleep and/or bad dreams.
  • Brain structure: A person’s individualized brain structure may be the culprit for causing nightmares. Differing brain structures in conjunction with neurotransmission and activity may play a role in influencing the frequency and/or likelihood of bad dreams. There may be structural differences between those more prone to nightmares and those who rarely have a bad dream.
  • Brain waves: There are many different brain waves that influence our consciousness and sleep. During sleep, we tend to shift into theta waves and delta waves depending on the stage. It is these brain waves and/or a combination of brain wave rhythms that could lead a person to experience nightmares.
  • Depression: Individuals with depression may be more inclined to experience nightmares due to the fact that they experience a significant amount of negative emotions during waking hours. Since the person with depression may have frequent intrusive or negative thoughts, it’s no stretch to hypothesize that these thoughts and areas of brain activation could trigger nightmares.
  • Drugs: People who use drugs, of any kind – particularly illicit drugs with psychotropic effects may experience nightmares. Many drugs alter both brain activity, nervous system arousal, and neurotransmitter levels – potentially leading to bad dreams.
  • Eating before bed: Some believe that eating food before going to bed can lead a person to experience nightmares and other dreams. The thought behind this theory is that when food is ingested, it triggers a metabolic response in the body, which is controlled by the brain. A person’s brain activity may then change as a result of the metabolic change, which leads to the nightmares.
  • Emotional state: What is your emotional state prior to going to bed? If you are emotionally disturbed and are experiencing sadness, depression, or fear – it may result in you having bad dreams. Keeping your emotions in check and mitigating the effects of negative emotions may help prevent and/or reduce the likelihood of bad dreams.
  • Fear: Is there anything in your life that you are particularly afraid of? Stimuli that provoke or promote fear may lead to bad dreams. Additionally, if we are afraid of something in our immediate environment such as a criminal or abusive partner, it may interfere with our quality of sleep – leading to nightmares.
  • Genetics: While it isn’t studied, it could be suggested that there may be a genetic component to experiencing nightmares. Some people are more prone to nightmares, specifically those with “nightmare disorder.” There could be specific genetics involved in sleep that influence brain activity, making some people more or less prone to bad dreams.
  • Medications: Are you taking any medications? Individuals taking medications, particularly those that elicit psychotropic effects are known to cause crazy dreams and nightmares. If you started experiencing nightmares after you began treatment with a specific medication, it’s pretty easy to figure out the culprit.
  • Movies: Movies within the “Horror” or “Crime” genres may make some people, especially children have nightmares. Certain characters within the movie may make individuals scared. Many horror and thriller movies prime the fear-center of the brain to make us scared. The effect can linger long after the movie has ended, inevitably causing some to experience nightmares.
  • Neurodegenerative disorders: People suffering from neurodegenerative disorders such as Alzheimer’s disease and dementia may be at increased risk for developing nightmares. These disorders are known for creating structural changes within the brain, functional changes, as well as altering neurotransmission. For a multitude of reasons, it is not uncommon for an individual with significant neurodegeneration to experience bad dreams.
  • Negative thinking: Those who dwell on negative aspects of life and have a pessimistic outlook may be more vulnerable to nightmares. Negative thinking may be the byproduct of a mental illness or personality disorder, but could increase odds of experiencing a nightmare.
  • Neurotransmitters: Varying levels of specific neurotransmitters may cause nightmares. People who take psychotropic drugs (prescription and illicit) often report experiencing nightmares. Many of these drugs make significant alterations to levels of neurotransmitters and their functioning. A highly plausible cause of nightmares for some people is abnormal or drug-induced changes in neurotransmission.
  • Psychosis: Those that have been diagnosed with psychosis and/or are in psychotic states may experience nightmares. Generally dysfunction within dopamine systems, particularly an increase can lead a person to experience psychosis. A variety of other mental processes may be affected by psychosis, which could increase vulnerability of experiencing nightmares.
  • Random elements: The random nature of dreams can sometimes be triggered by random elements. In many cases the cause of them is unknown and can only be attributed to the highly random nature of dreams. For some people, there may not be a specific cause behind their nightmares.
  • Reading material: Certain books and/or news articles may influence a nightmare, particularly those that induce fear. Someone that reads horror fiction may be more likely than average to have scary dreams. Others may read a scary article in the news that triggers a fear-based response in their body – this could lead them to later experience a nightmare.
  • REM Sleep: This is a specific stage of sleep known as “rapid-eye movement” (REM). It is during this stage of sleep that we are known to have vivid dreams. Some believes that during this stage of sleep our brain sends random signals and deciphers some sort of story. Possibly by reducing the amount of rapid-eye movement sleep we could decrease nightmares.
  • Scary stories: People who recently heard a scary or fear-provoking story throughout the day and/or prior to falling asleep may be more likely to experience a scary dream. In many cases the information that we prime our brains with before bed resurfaces during sleep.
  • Schizophrenia: Individuals with schizophrenia often become disconnected with reality and prone to hallucinations and/or delusions. Due to the fact that this condition takes such an extreme toll on a person’s life and entire brain functioning, it is possible that these individuals would be more prone to experiencing nightmares.
  • Sickness: Individuals that are sick with viral infections can often experience bad dreams and nightmares. This is a result of the body under increased stress trying to fight off a sickness. The increased physical and mental stress as a result of being sick is thought to potentially trigger nightmares.
  • Sleeping position: Some people are thought to experience nightmares as a result of sleeping in an odd position. Someone who is uncomfortable prior to going to bed and/or is lying in an unnatural position may be at greater risk for nightmares.
  • Stress: Some scientific studies have shown that people with high levels of stress in their life are more likely to experience nightmares. A study conducted with children showed that a death in the family and/or family member with a chronic illness can significantly increase the likelihood of nightmare occurrences.
  • Subconscious: This is part of your brain that is beneath your conscious awareness hence being called “sub”-conscious. The subconscious may contain buried or repressed emotions, memories, and/or a collective of material that it is exposed to throughout the day. Individuals that expose themselves to significant violence, fear-based media coverage, and fear-inducing TV shows may be more likely to have nightmares as a result of subconscious expression.
  • Supplements: Any supplements that have an influence on brain functioning or neurotransmission could lead to changes in the sleep cycle. Since many people take supplements for a variety of conditions (including insomnia) it is important to consider that the supplement may be a direct cause of nightmares in certain people.
  • Traumatic experience: Those who have experienced some sort of trauma, specifically PTSD (post-traumatic stress disorder) are likely to have nightmares reflecting the trauma. During dreams it is common for highly-emotional material to surface and/or haunt us. People may have nightmarish flashbacks to the event in which they endured the trauma. Until a person learns to properly manage their trauma and properly cope, the nightmares may be recurrent.
  • Video games: Specifically video games that promote violence may be a culprit for causing nightmares. Games that involve any sort of shooting, killing, and/or fear-inducing situations may trigger that same emotional response in the brain. If a person plays a lot of violent games, it could lead to nightmares.
  • Withdrawal: A person withdrawing from a psychotropic medication and/or other illicit drugs may be more at-risk for experiencing nightmares. During withdrawal a person’s brain is undergoing many chemical changes and attempting to make adjustments. This may make an individual increasingly vulnerable to experience bad dreams.
  • TV Shows: There are a variety of shows on TV that may lead a person to experience nightmares, but not all are fictional. A person who watches a significant amount of news may start fearing for their safety based on what they see. The news these days mostly contains negative events, which essentially primes a fear-based response in your brain. Other shows like Dateline or those that are intended to scare like American Horror Story may also trigger nightmares.

Note: It is important to realize that nightmares can be caused by a variety of factors on this list. For one person, pinpointing a specific causal factor may be easy, for others the cause may be more complex such as interplay between a variety of factors.

Have you had a nightmare? Do you have recurrent nightmares or bad dreams?

Nearly everyone has had a nightmare at some point in their lives. I know I’ve had nightmares and still do every once in awhile. While they are very uncomfortable, especially if you’re really caught up in the dream, the emotional response eventually drowns out when we become conscious and realize that it was just a dream.

Some individuals with recurrent nightmares and/or nightmare disorder may reduce their frequency and/or intensity of nightmares by making conscious changes. If you have experienced your fair share of nightmares or know certain factors that may cause them for you, feel free to share your thoughts in the comments section below.

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{ 6 comments… add one }
  • AJ December 3, 2014, 2:24 pm

    For sure Wellbutrin has caused me to have bizarre dreams and/or nightmares. At first they were absolutely awful, but after several months they’ve gotten far more tolerable.

  • emotional reck June 2, 2015, 1:04 pm

    I constantly have dreams that my husband of almost three years, also the father of my two children, is going to leave me for someone else. Even if I don’t think about it during the day I still find that it haunts me in my dreams. Then when I do think about it in the day I’ll have a dream about it and its like I can’t get out of my head no matter how hard I try.

  • Jesse Swengel August 2, 2015, 2:46 am

    I was in a car accident in April 2015. Since then I have been having nightmares very frequently almost every night without medications. The nightmares have know relation to the accident. I did hit my head pretty hard. For a while I wasn’t able to remember where I parked my car. I almost fell into depression. I shakes it off. The nightmares began somewhere between the accident and when I meet with a neurologist. I was given medication, nortriptyline. It doesn’t always work but it helps. I have looked for ways nightmares could be related to post concussion issues. Looking for help.

  • Kristina March 5, 2016, 5:22 pm

    I’ve been having frequent nightmares suddenly. They are so real it’s like I’m in a detailed movie and I went through it all very realistically. I almost feel like it happened like I felt all the emotions during it very very heavily. My mom died a few years ago suddenly, then my dad got together right away with an evil b word and she covertly abuses me and I absolutely hate her and my dad has taken her side.

    So that causes severe daily stress in my current environment. I constantly feel depressed about it and cry also for my dog that died as well as my grandma whom I was a caretaker for, also I lost contact with a very important little kid I used to tutor. I don’t have a job right now, and my sister is another word. I don’t have any friends, just a boyfriend, and maybe that plays a part in it.

    I also used to be on drugs. The dreams I have are like one time I was getting arrested and going to jail and it was the most horrible feeling in the world. I woke up like very relieved to know it wasn’t really happening, or that it even didn’t happen at all. Last night I had one where I got into an argument with some neighbors I never seen before and they tried killing me for talking to cops and the cops wouldn’t come back to save us at all, and there was hella violence in it and blood.

    I am a highly sensitive person so maybe that plays a part in it.

  • Sian May 4, 2016, 12:23 am

    I have been suffering with depression and anxiety since I was about 13 years old I am now 20 and I am in a lot happier place than I was back then. I have been on the same medication just the doses have got higher over the years so I don’t see that as an issue. Recently over the last few weeks I have had very sick violent nightmares where I even wake up crying shaking in a pool of sweat with a banging headache.

    One dream was where I was in a street where I seen my dad get attacked by a dog and I mean it was vicious and nasty! The dog was on his face and it was like I was behind a glass and couldn’t get closer to help him. I love my dad to bits I can’t even bring myself to tell him about this nightmare. :'( Another nightmare I was in a big house with loads of men and I got dragged to a room where they held me down and forced needles into me and beat me up leaving me for dead!

    These nightmares are so terrifying and detailed… as if it was a movie you could say. I am frightened to close my eyes at night. It is starting to make me more depressed as I can’t get them out of my head through the day. Please if anyone have ever experienced anything as sick and scary as this please reply to this comment as I need advice.

    I have a 2 year old son relying on me me day and night I would dread to think of this affecting him as my emotional state is very very low right now.

  • Jennifer May 18, 2016, 10:32 am

    Dear Sian, I have these emotional nightmares as well, along with the rest of you. Don’t feel alone! I’ve lost more than five close family members and now when I take a nap I enter into some realm that is not right. I wake and feel all the normal feelings but I’m left with the feelings, like I just was in their presence?!?

    And it’s so real. I can touch them, smell them, and almost love them in the same room and then it gets taken away from me somehow, someway. Anyways I was just trying to include myself in your conversation and let you know you’re not the only one. Sometimes that makes all the difference. God bless and we all have a purpose. 🙌

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