Researchers in Germany have developed a way of enabling sleepers to control their dreams by applying electric current to the brain which prompts lucid dreams, involving a state of heightened awareness.
This allows the sleeper to recognise they are dreaming and influence what happens next. A similar concept was explored in the hit movie Inception, starring Leonardo DiCaprio.
However, unlike the film where DiCaprio's character infiltrates the dreams of others, the study only involved sleepers controlling their own dreams. In ordinary dreams, which occur during rapid-eye movement (REM) phase of sleep, the dreamer's conscious state usually has no access to past memories or anticipated events in the future, the researchers said.
In lucid dreaming, extra cognitive functions are involved such as self-awareness and free will.
This combination of brain activity may enable the dreamer to voluntarily control the dream plot.
While previous research has associated lucid dreaming with increased gamma activity in the frontal and temporal regions of the brain, it has not been clear if the lucid dream triggers extra gamma activity or if the gamma activity is the source of the enhanced dreaming.
People who have lucid dreams talk of "waking up" within a dream and being able, for instance, to fly at will or manipulate the imaginary world around them.
In the new study, researchers tested 27 participants with no previous experience of lucid dreaming over several nights. After three minutes of uninterrupted REM sleep a weak alternating electric current was applied to their scalps.
The scientists targeted the frontal and temporal brain regions where high-frequency "gamma" brainwaves had previously been associated with lucid dreaming.
Scientists targeted the frontal and temporal brain regions. Photo / Thinkstock
A few seconds after the brain stimulation the volunteers were awakened and reported having lucid dreams.
Stimulation at a frequency of 40 hertz both raised gamma activity and induced lucid dreaming.
It also correlated with specific aspects of lucid dreams, such as insight - realising you are dreaming - control over the dream plot, and dreaming in the third person.
Writing in the journal Nature Neuroscience, the team led by Dr Ursula Voss, from the JW Goethe-University in Frankfurt, Germany, speculated on the use of lucid dreams to help victims of post-traumatic stress disorder who are plagued by nightmares.
Lucid dreams could be induced using this technique and the dreamer could then be coached to alter the recurring dream into a less traumatic experience.
"Promoting gamma oscillations during REM sleep in post-traumatic stress disorder with re-emerging nightmares might trigger lucid dreaming and eventually enable active changes in dream content," she wrote.