Freddy Krueger has a new problem to worry about. Researchers say they might have found an improved way to fend off frightful nightmares: a dose of sound played during sleep. The method could boost the effectiveness of an existing therapeutic treatment for people with chronic nightmares.
Just about everyone has had a nightmare, with about three-quarters of people thought to have experienced at least one by early childhood. But some people grapple with especially frequent nightmares that negatively impact their sleep or daily lives. Around 4% of the general adult population might suffer from frequent nightmares at any given time, and nightmares are even more common for people with certain mental health conditions, such as post-traumatic stress disorder.
There are some medications used to help treat PTSD-related nightmares, but the primary treatment for nightmare disorders is a cognitive-behavioural technique called image rehearsal therapy (IRT). IRT asks patients to think back on their nightmares and to then imagine a new, happier ending to them. It’s hoped that these mental exercises will bleed over into the dream world, leading to an easier night’s sleep.
While IRT can be effective in helping people manage their nightmares, as many as 30% of patients don’t respond to it, and even those who do benefit might continue to have nightmares. Researchers at the University of Geneva in Switzerland wanted to test out whether they could improve these odds of success by adapting an existing technique known as targeted memory reactivation (TMR).
Other research has shown that people can perceive sounds and even odours during sleep. Targeted memory reactivation is said to work by training people to associate a newly formed memory or newly learned skill with a specific sound cue, which is then played during sleep. And studies have found that trained people do seem to remember or better perform their new skill afterward than untrained people. This research has largely involved the use of targeted memory reactivation during non-REM sleep, though, so the researchers wanted to see if it would still work during REM sleep, the brief periods of our rest where the majority of dreams and nightmares occur.
They recruited 36 people with nightmare disorders to take part in their study. Every patient went through IRT, but half were randomised to associate their new dream ending with a sound cue (a piano chord). Over the next two weeks at home, all of the patients recorded their dreams in a diary and had their brain activity monitored with a headband they wore at night. But those who were given the added sound therapy also had their headbands play the sound cue every 10 seconds during REM sleep. The patients were then followed up right after the two-week period and three months later.
Overall, both groups reported fewer nightmares on average than they did before, but those in the sound group experienced even fewer nightmares. Three months later, for instance, people in the control group reported an average of 1.5 nightmares a week, while those in the sound group reported less than 0.5 nightmares a week. People given the sound cue also reported having more dreams where they simply felt joy.
“The present study establishes that associating TMR to IRT reduces nightmare frequency and fosters positive emotion in dreams,” the researchers wrote in their paper, published Thursday in Current Biology.
The study has a relatively small sample size, so the results shouldn’t be seen as definitive proof that sound cues can help people chase away bad dreams. But if these findings are validated by additional, larger studies, then the applications of targeted memory reactivation during sleep might extend well beyond nightmare therapy, the authors argue.
“We propose that TMR in REM sleep could be used as a new ‘sleep therapy’ in other psychiatric disorders,” they wrote, including PTSD in general, mood disorders, and insomnia.