During sleep, certain neurons work on removing unnecessary information from the brain. In their study published in the Science journal, researchers from Japan and the US said that while sleeping, the human brain processes the information and events that took place during the day.
Researchers led by Shuntaro Izawa from Japan's Nagoya University, said the brain store or remove the information based on its level of importance, reported the German News Agency.
According to scientists, forgetting is an active process in the brain. The researchers said they know nothing about the neural processes behind forgetting or remembering, or about the sleep stage during which the information sorting and removal takes place.
Humans go through two sleep stages: the rapid eye movement sleep (REM) and the non-rapid eye movement (NREM); the first starts about 90 minutes after drowsiness, and features excessive eye movement, muscles relaxation, and increased heart rate.
The rapid eye movement sleep (REM) is also known as the dreaming stage, during which the sleeper dreams actively. In previous studies, scientists suggested that the human brain removes some memories during the rapid eye movement sleep stage (REM).
In the new study, the researchers examined the role of the so-called MCH cells in the hippocampus, a peanut-size region found in the bottom of the brain. These findings may explain why people forget their dreams quickly, "since the dreams mostly take place in the REM stage, during which the MCH cells are highly active."
They also suggested that this high activity may be inhibiting the storage of dreams in the hippocampus, which makes people forget their dreams swiftly," said Neuroscientist Thomas Kilduff.
