I’m a sleep expert, but that doesn’t mean I’m immune from nightmares. Like most people, I have the occasional bad dream or nightmare (we’ll look at the difference in just a minute), the kind of dream that wakes me up in a fright or leaves me feeling a little “off” the next morning. It does not happen often to me, but I have some patients for whom nightmares are more frequent.
What is a nightmare?
Nightmares are frightening dreams that wake people from sleep. How are nightmares different from bad dreams? Technically, if a disturbing dream doesn’t push you over the sleep/wake line—or even into that hazy middle ground between sleeping and waking—then it isn’t a nightmare. Bad dreams are essentially a less severe and less disruptive form of nightmare. Like nightmares, bad dreams can cause emotional upset and affect how you feel the next day, but the emotional distress tends to be less intense. Nightmares happen less frequently than bad dreams.
Nearly all of us experience nightmares at some point in our lives. For most people, nightmares are a pretty rare occurrence. Some people have nightmares more regularly, but not frequently. And a small percentage of the population—studies estimate around 5 percent—have nightmares as often as once a week.
Nightmares typically happen during REM sleep, during the middle and later portions of the night. Because of where nightmares tend to fall in the sleep cycle and the intensity of their imagery and emotions, nightmares result in some degree of awakening. You may bolt upright in bed and have trouble returning to sleep. Or you may become partially awake, enough to register fear and disorientation and perhaps some relief that your nightmare was “only a dream” before you fall back asleep.
What are the most common nightmares?
None of us enjoy thinking about our most upsetting dreams. But the truth is that we’re dreaming about a lot of similar things. Just as ordinary dreams cover many similar subjects and themes across generations and cultures, so do nightmares. A study that analyzed more than 10,000 dream reports found the most common themes in disturbing dreams included:
Not surprisingly, fear was found to be the most common emotion in nightmares. But fear isn’t always present in nightmares. Researchers found that one-third of nightmares did not contain fear, but instead focused on other emotions like sadness, grief, guilt and regret, and disgust.
Did you know that men and women tend to have different types of nightmares? The dream-report study showed that men are more likely to have nightmares focused on disasters and violence—think fire, flood, and war. Women are much more likely to have nightmares centered around interpersonal issues. Women also appear to have nightmares more frequently than men, according to the research.
Why do we have nightmares?
We don’t know for sure the purpose of dreams, and the underlying reason for nightmares isn’t clear, either. Nightmares have a place in the virtual reality and threat-simulation theories of dreaming. It is possible that nightmares are a way that the brain forces us to practice, prepare for, and even anticipate difficult or dangerous experiences in waking life. Nightmares may be a way that that the brain points us toward issues and emotions that need attention in our waking lives.
Of course, it’s possible that nightmares, like dreams in general, don’t have a primary function; that they’re a by-product of other activities in the body. But most sleep scientists think that dreams and nightmares exist for some purpose.
Conditions associated with nightmares
Nightmares aren’t just tough on your emotional well-being. They also cause sleep problems. Nightmares disrupt sound sleep and can leave you feeling tired and shaken the next day. Nightmares can be so disturbing that they make you feel afraid to fall back to sleep, depriving you of important hours of rest.
Certain sleep disorders may be accompanied by bad dreams and nightmares. Insomnia can heighten dream recall and lead to more stressful and disturbing dreams. In turn, nightmares can trigger insomnia. Obstructive sleep apnea, because of its ability to disrupt normal REM sleep, can cause disturbed dreaming with more bizarre and negative dream content. Narcolepsy (a disorder that involves extreme daytime tiredness and altered sleep-wake cycles) can also lead to more negative and bizarre dreams. Restless Leg Syndrome (RLS) (a neurological and sleep disorder) can also be accompanied by nightmares.
Poor sleep isn’t the only health issue linked to nightmares. Nightmares are associated with a number of mental and physical health problems. They can be a symptom of other health conditions and contribute to worsening health conditions.
Depression and anxiety often are accompanied by nightmares—and the presence of nightmares may be an indication of a more severe depression. People who are depressed or anxious are more likely to have stressful, disturbing, or frightening dreams, sometimes in the form of recurring dreams. There’s a complex relationship between nightmares and depression that runs in two directions: Depression may cause more frequent nightmares, and nightmares themselves may contribute to worsening depression.
One type of drug commonly used to treat depression may alter dreaming. SSRIs (selective serotonin uptake inhibitors) appear to affect dreaming in several ways. SSRIs may decrease dream recall. This type of drug may also intensify dreaming. SSRIs may lead to the presence of more positive emotions in dreams. Withdrawal from SSRIs, on the other hand, may lead to nightmares and may also intensify dreaming.
Drugs and alcohol also can affect dreaming. Alcohol disrupts the normal, healthy sleep cycle and leads to fragmented sleep. Consuming alcohol heavily and too close to bedtime may alter and diminish time spent in REM sleep. Studies show that alcohol dependency is linked to dreams with more negative emotional content. Marijuana also disrupts and reduces REM sleep. Withdrawal from marijuana and cocaine have been shown in studies to induce strange dreams.
Nightmares and disturbed dreaming are hallmark symptoms of post-traumatic stress disorder (PTSD), as is disrupted sleep. People who suffer PTSD often experience frequent and recurring nightmares, which may be accompanied by acting out during dreams. PTSD occurs in some people who’ve experienced trauma such as assault, disaster, war, and combat. Soldiers who’ve served in active combat often experience sleep problems and nightmares linked to trauma and PTSD.
After years of observing a particular group of symptoms among combat soldiers, sleep scientists have proposed we recognize a new sleep disorder: Trauma Associated Sleep Disorder, which has symptoms including nightmares, sleepwalking, and other disruptive nighttime behaviors.
Nightmares may accompany degenerative neurological conditions, including Parkinson’s disease and some forms of dementia. Violent and aggressive dreams, along with physically acting out during dreams, are frequent symptoms of neurological degeneration. These dream-related symptoms also have been identified as a strong predictor of future development of a degenerative neurological disease.
Nightmares vs. night terrors
Another scary dream-like experience is night terrors or sleep terrors. Night terrors are not the same thing as nightmares, though both are frightening and disruptive to sleep. Night terrors are very intense episodes of fright during dreams. When people experience night terrors, they often scream and yell, or thrash around in bed in a panic.
Night terrors occur during non-REM sleep dreaming, while nightmares tend to happen during REM sleep. Both adults and children can experience night terrors, but they are more common in children. Estimates suggest that as many as 6 percent of children experience night terrors, most often between the ages of 3 to 12. Night terrors sometimes run in families. There may be a genetic predisposition to night terrors, as well as to sleepwalking and other parasomnias. There is also evidence of a relationship among night terrors, sleep apnea, and enlarged tonsils and adenoids in children.
Getting relief from nightmares
If nightmares are a problem for you, there are steps you can take to reduce these frightening disruptions and improve your sleep. Nightmares have several possible root causes. Identifying the possible cause of your nightmares is an important first step. Talk to your doctor and ask for a referral to a sleep specialist to get help identifying the factors that may be contributing to your nightmares. Steps may involve:
Rewriting your nightmares
Image-rehearsal therapy is a technique that can help reduce nightmares and make sleep easier and less stressful. As part of this therapy, people "re-write" the stories of their nightmares, turning their scary scripts into happier, more peaceful ones. Image-rehearsal therapy can be especially effective for people who experience nightmares that are chronic or recurring.
Here’s how it works: You write down the all the details of your nightmare, telling its story from beginning to end. Then, you create a new version of the dream, one that turns a frightening story into a positive one. You visualize the new dream, playing it in your mind.
A nightmare that originates like this ...:
"I’m running along a dark and twisty path, I can’t see in front of me, and a giant creature is chasing me. I can’t run fast enough and the creature keeps getting closer and closer."
... might become something like this:
"I’m walking along a peaceful road in the woods. I’m alone, and I feel completely safe. I can take my time, feeling the breeze pass through the trees, smelling the woodsy scent of the forest, and enjoying presence of the birds and other small animals that are moving around their natural home."
Nightmares, bad dreams, and sleep terrors can be a difficult part of our sleeping lives. Fortunately, for most people, nightmares are a once-in-a-great-while sleep disruption. If you experience nightmares more frequently, and your nightmares are interfering with your sleep and your emotional well-being, don’t ignore them. Talk with your doctor or find a sleep specialist who can help you find relief.