The Heart-Pounding Science of Nightmares

We asked Alex Dimitriu, MD, a double board certified physician in psychiatry and sleep medicine, to tell us everything we (never?) wanted to know about nightmares.

A nightmare is any dream that is “unpleasant, embarrassing, stressful, or otherwise bad,” he says.

There’s really no official dividing line between good and bad dreams, so what constitutes a nightmare varies from person to person. One person may consider an embarrassing or cringy dream a nightmare, and another may just view it as a weird dream.

But generally, if it’s a dream that gives you bad vibes — even if it’s not explicitly scary — you can consider it a nightmare.

Dimitriu says, “The brain is essentially awake during REM sleep, and the body is paralyzed (on purpose).”

During this time, he explains, the brain is processing and storing memories, while also rehearsing past events and playing through potential future scenarios. Because of this process, dreams can be “good and bad in some ways, because that is also the reality of daily life.”

Preach, Doctor.

OK, but why are they so weird sometimes?

“During REM sleep,” Dimitriu explains, “the brain tests out new connections.” This is what makes dreams, well, dreamy, and why they can be so bizarre and random sometimes.

The seeming randomness, he says, is what makes some dreams (and nightmares) so very strange — but it’s all because “the brain is free to play during our dreams.”

According to some research, most people report having occasional nightmares. But if you’re having them regularly, there could be an underlying cause. So, let’s talk nightmare fuel (literally) — what might these underlying causes be?

Dimitriu says stress can be a really common trigger. “Nightmares can be stress dreams,” he explains, “which can indicate an elevated level of daily stress.”

It’s also fairly common for people with PTSD to have nightmares reliving and rehashing their trauma. “This, too,” he says, “is the brain’s attempt at processing sometimes painful memories.”

Finally, and horrifyingly, he explains the connection between nightmares and sleep apnea. “People with sleep apnea, where the airway is obstructed during sleep, will sometimes dream of drowning, suffocating, or otherwise not being able to breathe.” (P.S. If you needed a sign to stop putting off that sleep study, here it is.)

Can they predict the future or tell you things you didn’t even know about yourself?

The latter — maybe.

Some nightmares may have common themes, but it’s not necessarily that they mean something or that they’re prophetic in any way.

They just represent some of the common fears and concerns that are part of the human experience. Here are a few well-known nightmare tropes, some common themes identified by researchers, and some we’ve even experienced ourselves:

• giving a speech in your underwear (a classic)
• phone stops working at an important moment
• trapped somewhere and can’t get out
• being chased
• being attacked
• being paralyzed
• being late to something important
• injury, death, or disfigurement (such as the teeth falling out dream)
• disappearance of a loved one
• involvement in an accident or natural disaster
• presence of evil (vampires, zombies, ghosts, etc.)

As Dimitriu explained, remember that during REM sleep the brain is processing your memories, playing through past events, and roleplaying potential future events. If there’s a worry that’s preoccupying your waking mind, it makes sense that it would show up in a nightmare in some way (after being passed through the bizarro-world filter).

Now let’s talk about some of the more insidious forms of nightmares: night terrors and sleep paralysis.

Night terrors happen when you wake up absolutely terrified. You may sit up in bed, scream, cry, or start panicking. They mostly happen to young children but can occur in adults as well. Interestingly, they’re considered a type of parasomnia (an unwanted behavior during sleep, like sleep-walking) — and they mostly happen when you’re transitioning between sleep stages.

Sleep paralysis is a terrifying but all-too-common experience during which you feel fully conscious, but you’re unable to move. You may feel like you’re being pinned down, or like something — or someone — is holding you down or sitting on your chest.

It happens when your body is transitioning between wakefulness and sleeping. Essentially, your entire body is asleep… except for your brain, which is in a hazy, half-awake state. According to some research, it may be linked with post-traumatic stress disorder and panic disorders.

Feeling the hairs on the back of your neck standing up yet? We won’t tell you that some people with sleep paralysis can also experience hallucinations during these episodes, then.

Occasional nightmares are typical and shouldn’t affect your day-to-day life too much, but frequent nightmares can be harmful to your health. In the most severe cases, they may cause:

Frequent nightmares may also deteriorate the mental wellness of people with preexisting mental disorders. For example, one study found that nightmares can worsen PTSD symptoms and accelerate the condition’s development.

But what’s the solution, barring some “Inception”-level sleep interventions?

Well, lucid dreaming — where you recognize that you’re dreaming and thus are able to control the dream — is one such “Inception”-y strategy that actually may really work once you learn how to do it. There’s a whoooole Subreddit about it if you’re interested in diving deep.

To get back to sleep after a particularly rough nightmare, though, it’s best to breathe deeply until you’ve calmed down, then roll back over and try to go back to sleep — rather than dwelling on the contents of your nightmare.

And here are some strategies Dimitriu recommends for helping to prevent nightmares off the flip:

It’s also a good idea to try to start managing your stress if it seems out of control, because that may be a major contributor. If you need help, you should definitely reach out to a therapist or a sleep specialist.

Dimitriu also leaves us with some wise words: “Because they mirror life, dreams too cannot always be perfect.”

According to Dr. Dimitriu, dreams are “possibly the best VR experience,” but they can go a little haywire and morph into unsettling, creepy, or straight-up disturbing nightmares sometimes. People with chronic stress or PTSD may have more nightmares than most people, but getting enough sleep, going to sleep and waking up at the same time each day, avoiding alcohol before bed, and de-stressing may help. And definitely don’t be afraid to reach out for professional help.

Sweet dreams!