Nightmares are common among the general population and psychiatric patients and
have been associated with signs of nocturnal arousal such as increased heart rate or
increased high-frequency electroencephalographic (EEG) activity. However, it is still
unclear, whether these characteristics are more of a trait occurring in people with frequent
nightmares or rather indicators of the nightmare state. We compared participants
with frequent nightmares (NM group; n = 30) and healthy controls (controls;
n = 27) who spent 4 nights in the sleep laboratory over the course of 8 weeks. The
NM group received six sessions of imagery rehearsal therapy (IRT), the ‘gold standard’
of cognitive-behavioural therapy for nightmares, between the second and the
third night. Sleep architecture and spectral power were compared between groups,
and between nights of nightmare occurrence and nights without nightmare occurrence
in the NM group. Additionally, changes before and after therapy were
recorded. The NM group showed increased beta (16.25–31 Hz) and low gamma
(31.25–35 Hz) power during the entire night compared to the controls, but not when
comparing nights of nightmare occurrence to those without. Moreover, low gamma
activity in rapid eye movement sleep was reduced after therapy in the NM group.
Our findings indicate, cortical hyperarousal is more of a trait in people with frequent
nightmares within a network of other symptoms, but also malleable by therapy. This
is not only a new finding for IRT but could also lead to improved treatment options in
the future that directly target high-frequency EEG activity.
Journal of Sleep Research Volume 33, Issue2 April 2024 https://doi.org/10.1111/jsr.14003