How to prevent nightmares, according to a sleep psychologist

A 2010 study conducted in Hong Kong states that approximately one of every 20 individuals reported experiencing nightmares at least once a week.

However, Dr. Michael Nadorff, Associate Professor of Psychology at Mississippi State University and President-Elect of the Society of Behavioral Sleep Medicine, says it’s important to note that not all individuals who have nightmares remember them. Nadorff explains that the majority of dreams are actually negative, but most of them come and go without being remembered.

Here’s what Nadorff has to say about nightmares, as well as how to prevent them, or at least how to keep yourself from remembering them.

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What causes nightmares?

Nadorff, who specializes in nightmares, says everyone has negative dreams, but not everyone remembers them. “You don’t usually remember them unless you wake up during them,” he explains. According to Nadorff, waking up from REM sleep, when dreams occur, is the only way to remember a nightmare.

Waking up from REM sleep is not bad for you, according to Nadorff. In fact, people wake up more frequently than they may realize during the night. A full sleep cycle takes roughly 90 to 110 minutes, and REM is the last stage of sleep, after which people typically wake up. About these nighttime awakenings, Nadorff says, “We kind of look around, make sure the house isn’t on fire and then fall back asleep, and if that happens within about five minutes, you’ll never remember it happening.”

While nightmares can be scary, Nadorff explains that they can be a sign that your brain is adequately taking care of itself. Experiencing nightmares within a month of trauma is actually healthy, according to Nadorff, who says nightmares can act as exposure therapy. “If it’s in the first month after trauma, that’s actually normal and healthy,” he explains.

Recurring nightmares, especially those that wake you up in the middle of the night, can be frustrating to experience. Many details about dreaming are not known beyond a doubt, but Nadorff has a take on why people are awoken by recurring nightmares. “I think it’s actually an avoidance behavior,” he says. “Think of an awakening as an avoidance of a negative dream, but in doing so, you also remember that you had the dream.”

How to avoid nightmares

To avoid waking up from and remembering potentially troubling nightmares, Nadorff has a few recommendations.

The most important step is establishing a normal sleep routine. “Having a bedtime and a wake time that is roughly the same every day does wonders,” Nadorff says.

He also says temperature can play a factor in waking up from REM sleep, which could cause you to remember a nightmare. He explains, “REM sleep is one of the few times your body is unable to control its own body temperature, so your body temperature drops while you're in REM sleep.” He continues, “What used to feel warm and cozy now feels hot and sweaty because of your body temperature in relation to the room around you.” Potential solutions to this include sleeping with fewer blankets or setting your air conditioning to make your room a little colder at night.

Nadorff adds that drinking liquids too late in the night can also make it more likely for you to remember your nightmares. If you are in REM sleep when your body wakes you up, you are more likely to remember a negative dream you were having.

For those with persistent nightmares who have tried these basic recommendations to no avail, Nadorff recommends a treatment called image rehearsal therapy.

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What is image rehearsal therapy?

Image rehearsal therapy is actually quite simple. When patients are experiencing frequent nightmares, Nadorff says he recommends they rehearse a dream they would like to have. “We have them write a new dream out,” he explains, “and we have them practice that new dream, visualizing it as vividly as possible, about twice a day for five to ten minutes each time.”

Nadorff says visualizing an alternative dream in this way can trick the brain into thinking its content is significant. He says, “If you have something that’s very vivid that happens more than once in a day . . . the brain thinks, ‘This must have been pretty important. I’d better store this.’” Later on, when someone enters REM sleep, Nadorff explains their memory of the image rehearsal will be one of the memories that the brain will be likely to encode. “That’s why people will often report having that dream they’ve been practicing,” he concludes.

This article originally appeared on USA TODAY: Why do we have nightmares? And how to stop recurring bad dreams.