Why Do We Have Nightmares?
27 Jul 201715:18 PM
Why Do We Have Nightmares?

Rosie Osmun

The Huffington Post
Teeth falling out? Lost in the wilderness alone? Being chased but can't scream? Most of us can remember at least one such dream for its vividness, resulting visceral fear and lingering discomfort.

What was your last bad dream about? Despite our unique lives and experiences, if you asked a group of people this question, you'd likely see a few common themes. In fact, research shows we tend to share quite a bit of subject matter in nightmares.

A 2014 University of Montreal study, analyzed 253 nightmares and 431 bad dreams. They found that physical aggression was the most prevalent theme in nightmares, along with death, health and threats.

Men's nightmares were more likely to involve themes of natural disasters and war, while women showed higher frequency of interpersonal conflicts. While fear was a common emotion evoked by nightmares, a significant portion caused sadness, confusion, fear or disgust as well.

Below are all the factors that influence your dream content:

- Your Experiences

For most people, dreams tend to incorporate aspects of our waking lives in both literal and abstract ways. For example, you dreams may include things like studying, test taking, a problem you're dealing with, working, family or a repetitive action you do during the day. Negative things like stress, fear, worry, arguments and other aspects of our days could also show up in nightmares.

The most common timeframes for dreams to incorporate episodic events and experiences is after one to two days or five to seven days. Dreams also commonly involve past autobiographical experiences, our personal experiences and long-term memories of the self. Research shows these memories are .typically experienced selectively and in a fragmented fashion

- Anxiety and Stress

Stress and anxiety can come in many forms, from temporary everyday things like moving to a new place, changing roles at school or work, or failing at a task, to more major things like divorce, losing a family member, trauma, or anxiety disorders. Being stressed and feeling anxiety is associated with poor sleep in general, and both may also trigger a nightmare.

Anxiety regarding performance is one a common theme you may have recognized in your own dreams. For example, about 15 percent of German athletes in one study reported distressing dreams before a big event, most often involving athletic failure. Many students also experience bad dreams related to impending tests or finals, sometimes even years after they've finished school.

- Media

The idea that scary movies, thrilling or suspenseful shows or even fear-inducing news broadcasts cause bad dreams is often expressed anecdotally. While difficult to study, many of us can recall a time where visual imagery and situations from media popped up in dream content. Scary movies can also cause stress and anxiety for some people (setting the stage for distressing dreams).

An older study of college students found that 90 percent could recall a frightening TV, movies or other media experience, and half said it had affected their sleep or eating habits in childhood or adolescence. More surprising is that about one-fourth of the students said they still experienced some residual anxiety. Blood, injury, disturbing sounds, and distorted images were the most prevalent types of phobia-inducing stimuli the researchers identified.

- Depression

Severe depression and a negative self attitude were associated with higher incidence of nightmares in a recent large Finnish study. Depression actually proved to be the strongest predictor in their research, with 28 percent of sufferers reporting frequent nightmares compared to the sample average of 4 percent.

- Personality

One study found adults with personality traits like distrustfulness, alienation, and emotional estrangement were more likely to experience chronic nightmares. Long-time dream researcher Ernest Hartmann proposes that people who have thinner personality boundaries and higher creativity may be more susceptible to nightmares.

Another interesting association is political ideology. A study of college students found that the conservative participants reported more nightmares and more fearful content than liberals, while the liberals recalled more dreams overall.

- Environment

Sleep research has documented that temperature and comfort can affect sleep quality, and environment may have some impact on dream content as well. Temperatures that are too cold or too hot can lead less restful sleep and more awakenings (meaning more remembered dreams), as can pain.

Scent may also play a role. A German study released the scent of rotten eggs or roses into the rooms of sleepers after they entered REM sleep. Upon being awakened, people smelling roses reported more positive dream content while those smelling rotten eggs reported more negative content.

- Traumatic Experiences

Recurring or more frequent nightmares have been linked with traumatic experiences, including events like relationship violence and surviving natural disasters, and it's a defining characteristic of posttraumatic stress disorder.

Those with PTSD experience nightmares much more frequently, with research estimating 52 percent to 96 perent experience them often, compared to around 3 percent of the general population. The National Center for PTSD says that nightmares following trauma tend to incorporate similar elements or themes as well as replays of the event.

- Medications and Drugs

Certain types of medications, particularly those that influence neurotransmitters may influence nightmare frequency. These include antidepressants, narcotics, and barbiturates, as well as withdraw from other drugs that affect REM sleep. If nightmares start after medication changes, bring it up with your physician.

According to the National Institutes of Health's Medline website, nightmares may also be associated with alcohol consumption and withdraw or recreational drug use and cessation.

- Eating Before Bed

Snacking too close to bed can cause indigestion, and it may also influence your metabolism and dreams. One study linked junk food with nightmares, while another found that a spicy meal close to bed disturbs sleep, as summarized in a Lifehacker article.

- Other Influential Factors

1. Sleep deprivation: Experiencing insomnia and fatigue also increase the chances of frequent nightmares, according to the previously mentioned Finnish study.

2. Sleep disorders: People with sleep apnea, restless leg syndrome and other sleep disorders are more likely to experience nightmares.

3. Migraines: Migraine headaches may be linked with more recurrent dreams and nightmares.

4. Pain: One study showed 39 percent of people suffering from burn pain experienced pain in their dreams, which was associated with more nightmares and more intense daytime pain.