Some people recall a dream every morning, whereas others rarely recall one, and now a team led by Perrine Ruby, an Inserm Research Fellow at the Lyon Neuroscience Research Center in France, has studied the brain activity of these two types of dreamers in order to understand the differences between them.
The research team sought to identify which areas of the brain differentiate high and low dream recallers.
In a study published in the journal Neuropsychopharmacology, the researchers show that the brain's temporo-parietal junction is more active in high dream recallers.
Increased activity in this brain region might facilitate attention orienting toward external stimuli and promote intra-sleep wakefulness, thereby facilitating the encoding of dreams in memory.
In the study, researchers used Positron Emission Tomography (PET) to measure the spontaneous brain activity of 41 volunteers during wakefulness and sleep.
The volunteers were classified into 2 groups: 21 'high dream recallers' who recalled dreams 5.2 mornings per week in average, and 20 'low dream recallers', who reported 2 dreams per month in average.
High dream recallers, both while awake and while asleep, showed stronger spontaneous brain activity in the medial prefrontal cortex (mPFC) and in the temporo-parietal junction (TPJ), 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," Ruby said.
"Indeed the sleeping brain is not capable of memorising new information; it needs to awaken to be able to do that," Ruby added.