An international team of researchers has identified a pattern of brain activity that correlates with angry emotions experienced during dreaming. The study, published in the journal JNeurosci, sheds new light on the neural basis of the emotional content of nightmares, a symptom of various mental and sleep disorders.
Emotional experiences are central not only to our waking life but also to the dreams we have during rapid eye movement (REM) sleep. However, few studies have looked at the brain mechanisms underlying the emotional aspects of dreams.
Now, study author Pilleriin Sikka, from the Department of Psychology and Turku Brain and Mind Center at the University of Turku in Finland, and colleagues from the University of Skövde in Sweden and the University of Cambridge in the U.K. discovered a shared emotional mechanism between our waking and dreaming states.
A total of 17 participants (10 women) underwent electroencephalography (EEG) recordings during two separate nights in a sleep laboratory. After five-minute bouts of rapid eye movement (REM) sleep, the researchers woke the participants and asked them to describe their dream and to rate their emotional experiences during the dream.
The researchers also analyzed two-minute pre-awakening EEG segments, as well as 8-minute resting wakefulness segments during their evening pre-sleep and morning post-sleep.
The findings show that participants who displayed greater alpha-band brain activity in the right — as compared to the left — frontal cortex during evening wakefulness and during REM sleep experienced more anger in their dreams. This suggests that people with greater alpha power in the right frontal hemisphere may be less able to regulate, or inhibit, strong emotional states while dreaming.
This neural signature — called frontal alpha asymmetry (FAA) — has been linked to anger and self-regulation during wakefulness. Together, these results suggest FAA may reflect a universal indicator of emotion regulation.
An estimated 50 to 80 percent of adults report having the occasional nightmare, according to the American Academy of Sleep Medicine. Around 2 to 8 percent of people have nightmares that can affect their sleep quality.
Previous research has shown frequent nightmares to be tied to low income, insomnia, sleep-disordered breathing symptoms, neuroticism and being female. People who suffer from nightmares are also five times more likely to have a psychiatric disorder.
Source: Society for Neuroscience