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Researchers Reduce Nightmare Frequency by Altering Dreamers’ Emotions

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An innovative study has shown that modulating dreamers’ emotions using therapy and audio cues could reduce the frequency of terrifying nightmares.

Researchers combined a well-established therapeutic approach for treating nightmares with an innovative and subliminal stimulus that enhanced the benefits of the therapy. The research, conducted by scientists at the University of Geneva, is published in Current Biology.

No more nightmares?

Nightmares are distressing experiences that virtually all of us have experienced. But for nearly 5% of the adult population, bad dreams become a much more serious issue. These people experience them more than once a week on average.

If such regular nightmares start interfering with one’s waking life, leading international classification texts for mental health disorders, such as the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V), start treating scary dreams as a recognized condition, called nightmare disorder.


Why do we have nightmares?

The reasons why nightmares occur remain unclear. The authors write that two main models exist – one suggesting that, like insomnia disorders and post-traumatic stress disorder, clinically significant nightmares are related to a state of hyper-arousal. Evidence suggests that the brains of individuals with frequent nightmares are more active during sleep.

Another theory relates to memory and fear extinction. This is a process by which the brain unlearns associations between scary events and fear if the association is no longer useful. For example, if we have a painful experience at the dentist, we might come to associate the type of music being played in the waiting room with fear. Under the fear extinction theory, a normal dreamer might hear that music, as the brain tries to reassociate it with a new scenario with a lower level of fear involved. Nightmares, however, are proposed to be a malfunction of this process, where the level of fear is not reduced, meaning the fear stimulus enters our sleeping mind.


Nightmares are so common that psychotherapists have developed a bespoke process for treating them, called imagery rehearsal therapy (IRT). First author of the study Dr. Sophie Schwartz explained how IRT works in an interview with Technology Networks. “IRT is a cognitive behavioral technique that encompasses the following steps: recalling the nightmare, changing the negative story line towards a more positive ending and rehearsing the rewritten dream scenario during the day.”

IRT practice takes just 5–10 minutes a day, said Schwartz. “A partial remission of nightmare frequency and severity has been observed after regular use of the technique for two to three weeks.”

But for around 30% of people with regular nightmares, IRT doesn’t help. To tackle this intractable issue, Schwartz and colleagues recruited 36 patients with nightmare disorder to explore an innovative combination approach.

The science of Inception

While 18 patients received IRT treatment as standard, the other half of the patient population were unknowingly subject to an additional intervention – the Inception-like targeted memory reactivation (TMR).

During these individuals’ IRT sessions, just when they were asked to imagine a happier version of their nightmare, a sound was played – a neutral piano chord. The researchers didn’t explain the purpose of the tone, but the TMR group were told to play the same sound while they practiced their IRT over the next two weeks. While they slept, all participants wore a headband device, the sleep tracker Dreem, enabling researchers to establish when the participants were in rapid eye movement (REM) dream sleep. Unbeknownst to the participants, the researchers had adapted the device to enable it to play the TMR-linked chord to all participants when they entered deep dream sleep.

The idea behind TMR is to help the brain associate cues together and boost learning. The researchers hoped that, without realizing it, the tone would help the sleeping participants recall the positive version of their nightmare scenario that they practiced during IRT, improving their sleep. One strength of this approach is that it largely eliminates “expectation effects”. These are confounding factors in experimental design that arise from patients expecting an intervention to make them feel better and getting a placebo effect boost from that expectation. With no knowledge that they were to be played the sound as they slept, the dreamers were free from such effects.

Dream a little deeper

While the participants who received IRT alone had fewer nightmares, those that also received the TMR tone were comparatively sound sleepers, said Schwartz. “The patients reported having fewer nightmares (disturbing bad dreams) over the two weeks of active treatment and still so after three months.”

At that three month-mark, TMR dreamers who had been plagued by almost three nightmares a week now had less than half a nightmare over the same period on average. Dreamers who were given just IRT had 1.5 nightmares per week on average, a significantly higher rate.

The researchers also surveyed the dreamers, through questionnaires and dream reports, on the emotional quality of their dream world, taking in nightmares and regular dreams. Those played the positively associated sound reported significantly higher levels of joy in their dreams compared to those who only had IRT.

The exact method by which this combination of techniques improves sleep quality remains to be deciphered. The participants in the trial didn’t directly recall the positive scenario that was rehearsed in the IRT sessions – a finding that was confirmed using a machine learning technique called latent semantic analysis to scan the dream diaries that participants produced.

While these unanswered riddles may keep the research team awake at night, what’s clear is that for those living with disruptive nightmares, this new technique has the potential to help them sleep more soundly.

Reference: Schwartz S, Clerget A and Perogamvros L. Enhancing imagery rehearsal therapy for nightmares with targeted memory reactivation. Curr. Biol. 2022; 32: 1–9. doi:10.1016/j.cub.2022.09.032