The delivery of benign electrical currents to the frontal and temporal brain regions at a specific frequency may induce lucid dreaming, during which the dreamer is aware that he or she is dreaming, reports a study published online this week in Nature Neuroscience.
During dreams in the 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. In contrast, lucid dreaming entails additional cognitive functions such as self-awareness and free will that 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, the exact nature of this association has been unclear.
Ursula Voss and colleagues assessed neural activity and dream ratings from 27 participants with no experience in lucid dreaming across several nights. Following three minutes of uninterrupted REM sleep, the investigators delivered transcranial alternating current stimulation (tACS) at frontal and temporal scalp positions, which alters neural activity in the underlying brain regions. A few seconds after tACS, participants were awakened, gave dream reports and rated various aspects of lucid dreaming. Stimulation in the lower gamma frequency band at 40 Hz (and to a lesser extent, 25 Hz) not only increased the power of gamma activity and induced lucid dreaming, but these power increases correlated with aspects of lucid dreaming: insight that one is dreaming, control over the dream plot, and dissociation from the dream’s protagonist. These findings suggest that increased gamma-band activity in frontal and temporal brain regions may give rise to lucid dreaming.