Maybe you’re inside your house, or walking through the park down the street. The scene around you is vividly real, yet altered in ways that are making you feel uneasy. Family and friends appear, but conversations produce a sense of anxiety or even dread. Disturbing emotions begin to build into fear, and then terror. You’re being chased. You’re trapped. You’re falling. Your life is in grave danger—then you’re suddenly jolted awake.
Emerging from nightmares, sweaty and with a pounding heart, provides at least a momentary sense of relief. It wasn’t real.
But the lasting effects of regular nightmares are very real. Nightmare disorder, a condition in which disturbing dreams are frequent and significantly impact life by producing fatigue or lasting feelings of unease and anxiety, is a surprisingly common ailment. In the United States, around 4 percent of adults—more than 10 million people—are affected. For those with nightmare disorder, lying down for a good night’s sleep can be an ordeal. They know that after they close their eyes, their brains will likely be flooded with negative emotions, and they’ll revisit a dreamworld they’d much rather avoid.
Now, a study published this week in Current Biology suggests an intriguing method that might help sleepers take more control of their dreams. Sounds played during sleep may reduce the frequency of nightmares and promote positive emotions that can help lead to a better slumber.
Existing therapies coach sleepers to imagine and rehearse alternate happy endings to their nightmares before bed, a practice known to significantly reduce bad dreams. Now, Swiss scientists aim to supercharge this idea by associating those happy endings with an audio cue that will trigger them during sleep. When nightmare disorder sufferers listened to a piano chord while they practiced imagining a good dream, then heard that same chord while they were in REM sleep, bad dreams were frequently kept at bay.
“We observed a spectacular clinical improvement, with a fast decrease of nightmares, together with dreams becoming emotionally more positive,” says Sophie Schwartz, a neuroscientist at the University of Geneva and co-author of the study. The decrease in nightmare frequency also showed staying power, lasting for at least three months after the audio experiment ended.
Schwartz and colleagues based their approach on imagery rehearsal therapy (IRT) a cognitive-behavioral technique in which patients work to remember what happens in their nightmares, then turn those negative scenarios around by creating a happier ending. By practicing for five or ten minutes each day at bedtime, rehearsing a new positive version of the dreams, they gradually reduce not only the number of nightmares they have but also their severity. “IRT is very well established and effective,” says Deirdre Barrett, a psychologist at Harvard Medical School who has written several books on dream research. “Lots of studies clearly show the benefits this kind of intervention where you coach people through designing alternate outcomes to their nightmare,” adds Barrett, who wasn’t involved in the new study.
But IRT doesn’t always work; 20 to 30 percent of patients don’t seem to benefit from it much at all. That’s why Schwartz and colleagues tried to supercharge its impact by pairing it with another technique that’s been employed to help boost memory during sleep.
With targeted memory reactivation (TMR), patients learn to associate a cue, like a noise or smell, with a learning procedure. Then, when they sleep, that cue is delivered to them again—a process that appears to prompt the sleeping brain to replay the procedure and strengthen memories of it.
In one TMR study on strengthening memory, for example, subjects were asked to memorize where objects were located on a computer screen. Each object had an associated sound, like a meow paired with a cat or a whistle with a teakettle. The group was then played some of those sound cues while they slept. When they awakened, the sleepers were considerably better at remembering where the objects associated with overnight audio cues were located than they were at finding those not associated with any sounds heard during sleep.
Schwartz and colleagues designed a test to see if such nighttime audio cues could also reactivate the specific memories associated with each patient’s IRT exercises, prompting them to avoid nightmares or turn them into more positive experiences. “By adding the audio cues, we are in a way ‘forcing’ the brain to reactivate the associated positive memory, which would thus be more likely to win the competition with the original nightmare,” she explains.
The scientists gathered a group of 36 patients who suffered from nightmare disorder and began using IRT to help manage the condition. Half of the patients pursued standard IRT, imagining and practicing positive alternative scenarios for their nightmares. While the other 18 patients did the same, they also heard a major piano chord every ten seconds, so they associated the sound with their positive dream revisions. Then, while this group slept at home in their own beds, they wore an EEG headband that measured brain activity to determine when they entered REM sleep, the time nightmares most typically occur. During REM sleep, the headband replayed the piano chord every ten seconds to test the hypothesis that associating the sound with good dreams could help trigger those memories while patients slept.
Patients recorded the types of dreams and emotions they experienced in daily dream reports, and they met with scientists to discuss dreams in clinical evaluations immediately after the study and again three months later. They reported that the overnight audio didn’t disturb their sleep, but they did notice other welcome changes. Those who heard the audio cues every night for two weeks found they had fewer nightmares than those who used IRT without the audio cues, and they also had more positive dreams. They reported feeling positive emotions like joy more often, and fear or anger less often. And the results lasted after use of audio cues had ended. Three months after the experiment, that group still reported fewer nightmares.
“It’s really an interesting study and a very cool thing to try,” says Barrett. “I don’t know whether this will turn out to be a significant improvement on nightmare intervention, but it seems possible based on this really small sample.”
The study is one of many that have attempted to use cues like sounds, light and even scent to prompt the sleeping brain into recalling things it experienced during wakefulness. The results aren’t always definitive, but they are intriguing. Another recent example used the sweet smell of roses, which wafted over students as they studied vocabulary words, then again during sleep, to significantly boost learning success and memory.
Schwartz and colleagues purposefully avoided including sufferers of post-traumatic stress disorder (PTSD) in the study. PTSD is characterized by other symptoms like anxiety and depression, and the scientists wanted to focus on the technique’s effectiveness at alleviating nightmares specifically without any confounding factors. But after the promising results, she notes, the next step will be seeing if the idea could help those still suffering the effects of past traumas even as they lie down to sleep. “For us, these findings are extremely promising both for the study of emotional processing during sleep, and for the development of new therapies, for instance for insomnia or for symptoms of post-traumatic stress, such as flashbacks and anxiety.”
For frequent sufferers, any sound that might trigger sweet dreams will definitely be music to their ears.