Bumps in the Night: What Causes Nightmares?

scary Halloween PumpkinIt’s that time again: Halloween, when bumps in the night often translate into spooky dreams. This is especially true for children. Young people often have repeated, terrifying nightmares, sometimes even night terrors—a less common parasomnia issue that causes intense feelings of panic or dread that can manifest in an unconscious scream or thrashing of the limbs. But children aren’t the only ones subject to monsters, ghosts, and criminals stalking their sleep.

Most adults can recall having at least a few nightmares in the past year. Carl Jung, widely considered one of the most influential psychologists of all time, was interested in dream analysis, and his work continues to be cited by websites and experts exploring what we experience in our minds when we sleep. Jung argued that the contents of our dreams represented universal unconscious archetypes, and that the meaning of these archetypes could be analyzed using the proper framework.

More recent research, however, indicates that nightmares are not nearly so esoteric in their meaning and that the meaning of dream content varies from one person to another. For one person, a dragon might represent fear, while for another it might represent a corporate logo. But what causes moments of nighttime fright? A few common causes:

Stress and trauma
People under stress are much more likely to experience nightmares, and trauma victims frequently have nightmares reenacting traumatic events. Some psychologists believe that dreams are the unconscious mind’s way of working out the day’s events, so it stands to reason that people under stress would be more likely to experience stressful dreams.

Both prescription and illegal drugs can cause nightmares. Some prescription drugs, such as sleeping medication and psychoactive drugs, alter the way the mind processes information and can greatly increase a person’s likelihood of having bad dreams. Similarly, intoxication can interfere with the brain’s normal processing mechanisms and cause nightmares.

Pre-bedtime thoughts
The things you think about immediately before going to bed can affect the content of your dreams. This is why late-night scary movies can wreck your slumber. Talking about frightening topics and late-night stress can also put a damper on your sleep, so if you’re prone to nightmares, leave the scary movies and stressful thoughts for midday.

For reasons that remain unclear, some people tend to have nightmares when they’re sick. Nightmares are especially likely when you have a fever, so consider taking a fever reducer before going to bed if you want to boost your chances of peaceful sleep.

Sleep problems
Sleep disorders such as sleep apnea may alter your dreams and cause nightmares. Sleep deprivation also can contribute to nightmares, though mental health experts are unsure why.

Snacking before bed, particularly on caffeine and sugary foods, is believed to cause nightmares in some people. It may be that these foods alter your normal bedtime alertness levels, making it more likely that you fall asleep worrying or deep in thought. Nighttime snacks may also interfere with normal sleeping patterns, which in turn might cause nightmares.

Sleep position
Some people find that they have nightmares when sleeping in a certain position, such as on their backs. There’s no failsafe sleep position, but if you always wake up in the same position after a nightmare, odds are decent that this sleep position is a contributing factor. It may be that some sleep positions subtly alter breathing or alertness levels, contributing to the development of nightmares. Alternatively, some sleep positions might make you feel more vulnerable than others, increasing the likelihood of nightmares.


  1. Nightmares in adults. (2012, July 30). WebMD. Retrieved from http://www.webmd.com/sleep-disorders/guide/nightmares-in-adults?page=2
  2. Mayo Clinic Staff. (2011, August 12). Nightmares. Mayo Clinic. Retrieved from http://www.mayoclinic.com/health/nightmares/DS01010/DSECTION=causes
  3. Nightmares. (n.d.). The New York Times. Retrieved from http://health.nytimes.com/health/guides/symptoms/nightmares/overview.html


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  • Janis

    October 31st, 2012 at 2:21 PM

    Worrying definitely is the number one trigger for me.Its not easy to fall asleep when worried.And when the sleep does come after so much tossing and turning I’m jumping out of bed a little later because I had a nightmare.Its almost a certainty that I will have a nightmare if I’m overtly worried about something.

  • Beattie

    October 31st, 2012 at 2:28 PM

    There are some nights that I will literally wake up in a cold sweat and I know that I was dreaming something terrible but I can’t for the life of me remember what it is sometimes even moments after waking. My heart will racing and I will have this recollection that something scared me so bad that it woke me up but I have no idea what it was about. And so if I can’t remember what it was about how do I make sure that I never have a dream like that again and what I can do to prevent it or even just analyze it?

  • ruby

    October 31st, 2012 at 3:35 PM

    Sure wish I knew because my son keeps me up every night trying to battle through his!

  • Conrad

    October 31st, 2012 at 11:59 PM

    Afraid of nightmares? Just do what I do. I keep looking at my hands and asking myself if I’m dreaming throughout the day. That way my mind gets tuned to asking that question. So when I’m having a nightmare I do the same and then realize its just a dream.

    From there it’s an easy lucid dream where I’m destroying zombies and monsters by the dozen with any weapon imaginable :D lucid dreams are awesome!

  • Nalia

    November 1st, 2012 at 4:02 AM

    I did not know that there could be physical elements to life like being sick that could contribute to having more nightmares. I have honestly never heard of that.

  • christopher

    November 2nd, 2012 at 4:18 AM

    Funny, I guess I always just thought it was fear.

  • Lane

    November 5th, 2012 at 4:52 AM

    When I took some very brief forays into the drug world, man, I had some dreams that would totally freak me out!

    Drugs and I were definitely not a good mix, and I am glad that I figured that out before I got too much trouble with them.

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