Each morning we wake up knowing our brains have been busy during the night.
Some people might recall a brief impression of a dream but won’t be able to recall specifics. Others won’t believe they have dreamed at all. Still others can recall their dreams in great detail. Why the differences?
A special edition of Popular Science called “The Science of Sleep” reports a 2013 study suggested differences in brain function for the differences in recall.
The Lyon Neuroscience Research Center in Lyon, France, asked 36 participants to spend a night in a sleep lab, hooked up to EEG sensors and wearing earphones that played different sounds at intervals, such as a male voice saying their first name as well as an unfamiliar first name.
The group was divided into low recallers (those who only remembered dreams once or twice a month) and high recallers (those who remembered their dreams almost every day).
The low recallers were more resistant to sounds interfering with their sleep, the article notes. High recallers were more reactive to the sounds, wakening more often.
“There is a strong hypothesis that awakening during sleep facilitates encoding a dream in memory,” says Perrine Ruby, the study’s lead author.
The groups also continued to show differences in brain waves when both groups were awake. High recallers had a greater spike in the brain’s electrical activity than low recallers when they heard their name.