"Nightmares are often referred to as a parasomnia," says psychotherapist Lee Phillips, LCSW, EdD. (Parasomnia is an umbrella term for sleep-disturbance disorders including nightmares, sleepwalking, and sleep paralysis.) "Nightmares can occur while the person is falling asleep, during sleep, or when waking up," he says. That said, most people report having nightmares during rapid eye movement (REM) sleep, a stage of sleep characterized by increased brain activity, heart rate, and breathing rate, and which happens in lengthier periods toward the end of sleep—which is why you might have more nightmares further into the night.
"Research shows nightmares may be caused by trauma, lack of sleep, medications, substance use, the viewing of horror films, reading scary books, and other disorders." —Lee Phillips, LCSW, EdD, psychotherapist
What causes nightmares is a bit of a mystery (as is the reason why some people get full moon dreams or nightmares), but dream research is slowly beginning to reveal more. "Research shows nightmares may be caused by trauma, lack of sleep, medications, substance use, the viewing of horror films, reading scary books, and other disorders," says Dr. Phillips.
Dr. Phillips notes that his own clients have experienced nightmares in conjunction with stress, anxiety, and depression. Alcohol and nightmares also have a correlation, given the fact that alcohol can shorten the amount of REM sleep you get; this leads the body to compromise with additional REM sleep (called REM "rebound") on the next night, creating room for more (and more vivid) dreams.
When those dreams show up as nightmares, they can take a few different forms. Below, Dr. Phillips breaks down the three types of nightmares and why you may be experiencing them, and offers a few strategies for keeping your sleep full of good dreams, instead. (Just remember: If your nightmares are regularly inhibiting you from a good night's sleep, it's a good idea to talk to your doctor to find out what personalized changes you can make to keep your time in bed more peaceful.)
3 types of nightmares and their effects on sleep quality
1. Idiopathic nightmares
Idiopathic nightmares are any imaginative dream sequences that are not the result of trauma. (They're the most common type of disturbed dreaming.) A person often starts having this type of dream in childhood, and they can follow you into your adult years.
"Idiopathic nightmares typically occur when a person is highly stressed," says Dr. Phillips. "They may also have these types of nightmares due to other mental health concerns such as anxiety, depression, bipolar disorder, and psychotic disorders."
Dr. Phillips says that idiopathic nightmares can lead to emotional irritability during the day. "Because of the high levels of stress, the person can experience emotional instability, which also leads to both initial and middle insomnia," he says, referring to the kind of insomnia that keeps you from falling asleep and the kind that causes you to wake up in the middle of the night, respectively.
2. Recurrent nightmares
As the name implies, recurrent nightmares are nightmares that repeat on a semi-frequent basis. Any kind of recurring dreams may be common in times of unmanaged stress and may reflect ongoing conflicts you can't or won't resolve. Classic examples include a dream where you show up to school naked (meaning you might feel unprepared for what the day has in store) and a dream involving snakes (meaning there might be some danger or conflict lurking in a part of your life that you aren't addressing).
"Recurrent nightmares can also cause irritability due to lack of sleep," says Dr. Phillips. "Often, people also get annoyed because it is the same dream repeatedly, or experience anxiety and worry because they fear the nightmares will never end."
3. Post-traumatic nightmares
Post-traumatic nightmares essentially re-enact a traumatic moment in vivid detail, and are common in people who have post-traumatic stress disorder (PTSD).
"Post-traumatic nightmares can cause severe symptoms of anxiety and panic," says Dr. Phillips, adding that they typically cause a person to have trouble both falling and staying asleep. Fortunately, researchers are beginning to develop treatment options for folks whose past is showing up in their dreams. If this sounds like you, it's a good idea to seek care from a mental health practitioner.
What do the most common nightmares mean?
"It is important to note that any dream can have multiple meanings, and at times, no meaning at all," says neuropsychologist Aldrich Chan, PsyD. "The way to know whether an interpretation is 'accurate' is to feel out how it impacts you. In other words, the accuracy of an interpretation relies on its productivity for you." With that caveat in mind, he shares three common themes that can occur in nightmares and what they typically mean:
A very common nightmare is falling off a building or cliff from a great height. "This may reflect a feeling of loss of control or insecurity in waking life, or even freedom, if it is accompanied with feelings of peace," says Dr. Chan. In order to properly interpret the meaning of a falling dream for you, it's helpful to think about the emotions you felt during the act of falling.
Another common nightmare theme is being chased, threatened, or pursued by something or someone. "This often represents feelings of anxiety, pressure, or avoidance," says Dr. Chan.
Likewise, being attacked in a nightmare is a theme that sleep doctors and psychologists see often. "Nightmares involving attacks, such as being chased, bitten, or physically harmed, can symbolize feelings of vulnerability, conflict, or powerlessness," says Dr. Chan.
Frequently Asked Questions About What Nightmares Mean
Who gets nightmares?
Nightmares, nighttime fears, and sleep disorders can affect anyone, from any background or upbringing, says Dr. Chan. However, he notes that certain medical conditions as well as stress, anxiety, and trauma can increase a person's likelihood of having nightmares.
As stated above, consuming mind-altering substances like alcohol can up your risk of having nightmares, and there's also a connection between taking melatonin and nightmares because of the way that melatonin fast-tracks the wake-to-sleep transition.
At the same time, plenty of people have no dreams at all, or more aptly, don't remember their dreams because they wake up in non-REM stages of sleep, and whatever happened during their dreams in REM sleep has long exited their recent memory.
What are nightmares trying to tell you?
"Nightmares are often trying to convey underlying emotions, fears, or unresolved issues," says Dr. Chan. "They serve as a means for the subconscious mind to process and confront these concerns, offering an opportunity for self-reflection and personal growth."
He stresses that by paying attention to recurring themes or symbols (it may help to write them down as soon as you wake up), you may be able to gain insight into an area of your life that may need some work or resolution.
Can nightmares be a warning?
Yes, nightmares can be a warning about a particular issue in your life. "If you are engaged in self-destructive behavior or activities that contradict your core values, a nightmare may show you where you are headed if you continue on the same path,” says psychologist Carder Stout, PhD.
Can nightmares predict the future?
"In the dream space, there is no linear time, so it may be possible to see certain elements of your future," says Dr. Stout. He says that there have been many times when his patients have dreamed about something that later has materialized in their waking lives.
That said, nightmares are more often a reflection of parts of your present life that you've been ignoring, fearing, or grappling with and need to address. As dream expert and psychotherapist Annie Armstrong Miyao previously told Well+Good: “Dreams are a way for us to process our experiences, express deep desires, sort out things that have been bothering or confusing us, or attempt to prepare for something that lies ahead or frightens us.”
What is the difference between a nightmare and a night terror?
Thought they sound similar, nightmares and night terrors are entirely different things. A nightmare is a scary or bad dream that startles you awake in a panic, sweating, or otherwise freaking out; by contrast, a night terror is a physical experience of screaming or thrashing about that happens entirely while you're asleep and of which you'll have no recollection afterward or the following morning.
Sometimes, you might wake yourself up in the midst of a night terror, much like you could wake up while sleepwalking—but just like with the sleepwalking, with a night terror, you'll have no idea why you were jolting around or yelling, or when you started. (In actuality, a night terror will likely be more terrifying to anyone who might witness someone having one than to the person who's actually having one.)
How do I stop having nightmares?
If you find yourself dreading bedtime because of frequent nightmares, Dr. Phillips recommends prioritizing self care above all else. "We may not be able to stop nightmares outright because they tend to take their own course of action, but we may be able to calm them by engaging in things like exercise, mindfulness, healthy eating habits, and psychotherapy," he says.
He also recommends refraining from drinking and making sure you leave at least a few hours between the time you take your last bite of dinner and the time you go to bed. Aligning your bedtime and wake-up time with your natural sleep type (aka your body's inclination to be sleepy or wakeful at different times throughout the day) can also help you find more restful sleep, as can meditating beneath the covers, listening to a sleep story, or doing something else that feels relaxing and safe for you.
Have trouble falling back to sleep after a terrible dream? Here's some guidance:
- Fleetham, John A, and Jonathan A E Fleming. “Parasomnias.” CMAJ : Canadian Medical Association journal = journal de l’Association medicale canadienne vol. 186,8 (2014): E273-80. doi:10.1503/cmaj.120808
- Rek, Stephanie et al. “Nightmares in the general population: identifying potential causal factors.” Social psychiatry and psychiatric epidemiology vol. 52,9 (2017): 1123-1133. doi:10.1007/s00127-017-1408-7
- Gieselmann, Annika et al. “Aetiology and treatment of nightmare disorder: State of the art and future perspectives.” Journal of sleep research vol. 28,4 (2019): e12820. doi:10.1111/jsr.12820
- Robert, Geneviève, and Antonio Zadra. “Thematic and content analysis of idiopathic nightmares and bad dreams.” Sleep vol. 37,2 409-17. 1 Feb. 2014, doi:10.5665/sleep.3426
- El-Solh, Ali A. “Management of nightmares in patients with posttraumatic stress disorder: current perspectives.” Nature and science of sleep vol. 10 409-420. 26 Nov. 2018, doi:10.2147/NSS.S166089
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