LYONS, France, Feb. 17 (UPI) -- French scientists say brain activity is behind the difference between people who can clearly recall nighttime dreams the next morning and those who cannot.
Researchers at the Lyon Neuroscience Research Center studying the difference between "high dream recallers," who recall dreams regularly, and "low dream recallers," who recall dreams rarely, report increased brain reactivity in high recallers may promote awakenings during the night, and may thus facilitate memorization of dreams during brief periods of wakefulness.
"High dream recallers" have twice as many episodes of wakefulness during sleep as "low dream recallers" and their brains are more reactive to auditory stimuli during both sleep and wakefulness, they said.
The research team sought to identify which areas of the brain differentiate high and low dream recallers.
Experiments to measure the spontaneous brain activity of 41 volunteers found high dream recallers, both while awake and while asleep, showed stronger spontaneous brain activity in the medial prefrontal cortex and in the temporo-parietal junction, an area of the brain involved in attention orienting toward external stimuli.
"This may explain why high dream recallers are more reactive to environmental stimuli, awaken more during sleep, and thus better encode dreams in memory than low dream recallers," research leader Perrine Ruby said. "Indeed the sleeping brain is not capable of memorizing new information; it needs to awaken to be able to do that."