According to the ”International
Classification of Sleep Disorders”, established by the American Academy of
Sleep Medicine, nightmares become pathological when they are recurrent and have
an impact during the day causing, for example, fatigue, anxiety, dysphoria or
intrusive nightmare imagery. This is known as ”nightmare disorder” and is an
increasingly common reason for medical consultation.

Nightmares are dreams with strong negative
emotions that occur during rapid eye movement (REM) sleep. Clinicians
distinguish them from simple ”bad dreams”. In contrast to nightmares, the
latter seem to have a useful function in promoting the regulation of emotions.
Scientists also make a distinction between traumatic nightmares – i.e. linked
to a state of post-traumatic stress – and nightmares without traumatic origin.

Treating nightmares

Imagery Rehearsal Therapy (IRT) is frequently
used to treat this disorder. This cognitive technique requires that the
patients imagine alternative and positive outcomes to their nightmare scenarios
every day for five to ten minutes. ”After two weeks of practice, it has been
shown that the frequency of nightmares decreases,” says Lampros Perogamvros, a
privat-docent in the Department of Basic Neurosciences at the UNIGE Faculty of
Medicine and a senior clinical fellow at the HUG’s Center for Sleep Medicine.

However, some patients are not receptive to
this method. To overcome this limitation and boost the treatment process, Dr
Lampros Perogamvros and his colleagues have coupled IRT with the Targeted
Memory Reactivation (TMR) method. By sending specific stimuli to the brain of
the sleeping person – often odours or sounds previously associated with recent
experiences – it is possible to reinforce the memory of this experience. In this
case, the aim was to reactivate memories related to the IRT exercises.

A piano chord played every ten seconds

The team from the UNIGE and the HUG gathered
36 patients suffering from the non-traumatic type of nightmares. Two groups
were formed: one to practice the coupled therapy, the other the classical
therapy with IRT only. ”We asked the patients to imagine positive alternative
scenarios to their nightmares. However, one of the two groups of patients did
this exercise while a sound – a major piano chord – was played every ten
seconds. The aim was for this sound to be associated with the imagined positive
scenario. In this way, when the sound was then played again but now during
sleep, it was more likely to reactivate a positive memory in dreams,” explains
Sophie Schwartz, a full professor in the Department of Basic Neurosciences at
the UNIGE Faculty of Medicine and the Swiss Center for Affective Sciences.

Each participant was then given a sleep
headband containing electrodes that measure brain activity. At home, thanks to
this device detecting the different stages of sleep, the piano chord was
replayed every ten seconds each time the patient reached REM sleep. The
exercise was repeated every night for two weeks.

More efficient and more lasting impact

At the end of the experiment, the frequency of
nightmares decreased in both groups, but significantly more in the group where
the positive scenario was associated with the sound. ”Moreover, this
association resulted in an increase in positive dreams,” says Alice Clerget, a
master’s student in the Department of Basic Neuroscience at the Faculty of
Medicine, who actively participated in the study. Finally, the benefits of the
coupled treatment were still perceptible three months after the experiment, with
patients in the TMR group still having fewer nightmares than those in the group
without TMR.

”While the results of the therapy coupling
will need to be replicated before this method can be widely applied, there is
every indication that it is a particularly effective new treatment for the
nightmare disorder. The next step for us will be to test this method on
nightmares linked to post-traumatic stress,” concludes Lampros Perogamvros.
These results also open up new perspectives for the treatment of other
disorders such as insomnia and other symptoms of post-traumatic stress, such as
flashbacks and anxiety.


Lampros Perogamvro et al, Enhancing imagery
rehearsal therapy for nightmares with targeted memory reactivation, Current
Biology, DOI


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