Why we have nightmares: Scientists reveal higher activity in the lefthand side of the brain is the reason we have angry dreams
- Researchers took brain scans of participants who also described their dreams
- Angry dreams were found associated with an imbalance in frontal brain activity
- Anger in both sleep and wakefulness might be caused by the same mechanism
- Findings may pave the way to new treatments for nightmares in those with PTSD
The secret of why we have angry dreams may finally have been found by scientists studying our brains as we sleep.
Experts found an imbalance between two regions of the brain found on both the left and right sides is to blame for the unsettling nightmares.
A tell-tale sign is an effect called frontal alpha asymmetry, where a specific type of brain activity is higher in one side of the brain.
The findings come from studies of 17 healthy volunteers who had their brains scanned before, during and after sleep.
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After they had experienced a five-minute bout of REM sleep, the researchers awoke sleeping participants and asked them to describe the dreams they had been having and rate the emotions they had experienced within such. (Stock image)
Researchers from the UK, Finland and Sweden looked at how our brains regulate emotions like anger and curiosity when we are dreaming at night.
Study participants spent two nights in a sleep laboratory, where researchers took electroencephalographic (or EEG) recordings of their brain activity for short periods before, during and after slumber.
Among the volunteers were 7 men and 10 women, all of whom were healthy.
Experts found that participants who experienced less brain activity in their right frontal cortex rather than its left-hand counterpart while they were awake and during REM sleep experienced more anger in their dreams.
‘It has been shown that expressing anger is related to relatively greater left [frontal activity], whereas controlling anger is related to relatively greater right frontal activity,’ said lead author Pilleriin Sikka, a researcher at University of Turku in Finland.
‘Anger was experienced in 41 per cent of dreams, interest in 88 per cent of dreams.
‘Participants experienced more anger in dreams than during the evening wakefulness, whereas the evening and morning anger ratings did not differ.’
The tell-tale sign of bad dreams, researchers say, is a signature called frontal alpha asymmetry, researchers report. The findings come from studies of 17 healthy volunteers (stock photo)_
Experts looked out for signs of the participants reaching rapid eye movement (REM) sleep.
This cycle of our sleep patterns is characterised by rapid eye movements, a faster pulse, quicker breathing, bodily movement and more dreaming.
Researchers woke participants after they had experienced a five-minute bout of REM sleep.
They then asked the sleepers to describe the dreams they had been having and rate the emotions they had experienced within them.
From these dream reports, the experts labelled the emotional states of the participants dreams – such as ‘angry’, or ‘interest’.
The only other emotional dream state that had a significant correlation with frontal alpha asymmetry during REM sleep was one closely related to anger – distrust or suspicion.
The findings suggest that this pattern of brain activity is a good way of predicting how people control their emotions.
Previous studies have linked frontal alpha asymmetry with both anger and general self-regulation while awake.
The new findings may help researchers to understand and potentially mitigate the emotional content of nightmares.
These can be a distressing symptom of many many mental and sleep disorders, including post-traumatic stress disorder.
The full findings of the study were published in the journal JNeurosci.
WHAT IS AN EEG AND HOW DOES IT WORK?
An electroencephalogram (EEG) is a recording of brain activity which was originally developed for clinical use.
During the test, small sensors are attached to the scalp to pick up the electrical signals produced when brain cells send messages to each other.
In the medical field, EEGs are typically carried out by a highly trained specialist known as a clinical neurophysiologist.
These signals are recorded by a machine and are analysed by a medical professional to determine whether they’re unusual.
An EEG can be used to help diagnose and monitor a number of conditions that affect the brain.
It may help identify the cause of certain symptoms, such as seizures or memory problems.
More recently, technology companies have used the technique to create brain-computer interfaces, sometimes referred to as ‘mind-reading’ devices.
This has led to the creation and design of a number of futuristic sounding gadgets.
These have ranged from a machine that can decipher words from brainwaves without them being spoken to a headband design that would let computer users open apps using the power of thought.