What causes nightmares?
Whatever happens to you before bed or earlier in the day is more likely to show up in your dreams than something that happened weeks before. Stressful events like an exam, natural disaster, or death of a loved one can cause an uptick in “garden variety” nightmares.
What shows up in your dream may not be the source of your stress and anxiety, but could create the same feelings: a terrifying loss of control, paralyzing depression, or crushing anxiety about the future.
Even things that aren’t real can spike nightmares. If a horror film reminds you of something that happened during childhood or it has a particularly terrifying moment like Psycho’s shower scene or The Shining’s, “Here’s Johnny…” it’s more likely to stick with you and appear in a nightmare.
“How vivid and striking the imagery or event is, or how much it happens to map on to something that’s important to you individually can cause nightmares,” Barrett tells Inverse.
By adulthood, most people know themselves and their propensity for nightmares, Barrett advises. Trusting your gut can help you decide whether to join your friends on a spooky adventure, or stay home.
“If you’re someone who has had nightmares about movies or scary scenes that you’ve seen in the past and you’re being pressured by your peers, don’t go! The odds are that it will potentially find its way into your dreams and stir up your anxieties,” the dream expert says. “But if you’re the kind of person that’s really excited by that gets an adrenaline rush and doesn’t much mind if it shows up in your nightmares, go for it.”
Some people’s nightmares might not seem scary to others, but they are terrifying to them personally.
“Some nightmare content is not about stuff that would seem that scary to anyone else. Some nightmares have this just horrible, sense of impending doom. While the actual content looks kind of boring to the average eye, it’s absolutely terrifying to that individual,” Barrett says.
Nightmares, like dreams, are universal: About a fifth of the general population reports experiencing nightmares every week. The two things have the strongest correlation with nightmares are general anxiety and something Barrett calls, the “dream intensity factor.” This factor hinges on how often people recall their dreams and how emotionally intense those dreams are, Barrett explains.
“It may seem counterintuitive, but to some extent, it’s the same people who are having these wonderful euphoric peak experience dreams that are likelier to have nightmares,” she says.
Young adults, in their late teens and early twenties dream the most, while nightmares peak in children. Anxious and depressed people, as well as those with psychological disorders like PTSD, borderline personality disorder, and schizophrenia have more nightmares than the general population. Certain medications and drugs have also been associated with nightmares. Antidepressants have been linked to less REM sleep and more bad dreams. A lack of sleep seems to exacerbate nightmares too.