Long-term Buddhist meditators with about 8,700 mean lifetime hours of practice show increased gamma power (25-40 Hz) in parietal-occipital regions during non-rapid eye movement sleep compared to meditation-naive individuals. This increase is specific to gamma frequencies, unrelated to spontaneous arousal levels during NREM sleep, and positively correlated with the length of lifetime daily meditation practice. The findings indicate that meditation practice produces measurable changes in spontaneous brain activity and suggest that EEG gamma activity during sleep may serve as a sensitive marker of long-lasting plastic effects of meditative training on brain function.
After two intensive days of mindfulness or compassion meditation, long-term meditators showed increased low-frequency brain activity (1-12 Hz, peaking around 7-8 Hz) over prefrontal and left parietal areas during non-rapid eye movement sleep. This increase was strongest early in the night and extended to higher frequencies (25-40 Hz) during the third sleep cycle. The changes depended on meditation experience and did not differ between the two meditation styles. No such changes occurred in meditation-naive individuals. The findings suggest that intensive meditation practice acutely alters brain activity in regions linked to top-down regulation, complementing chronic changes seen in posterior areas.