According to the researchers, spending too much time in dimly lit rooms might change the brain's structure and hurt one's ability to remember and learn.
‘When exposed to dim lights, the subjects lost about 30 percent of their hippocampus capacity (an area which controls memory and learning). They also performed poorly on a spatial task they had trained on previously.’
For the study, published in the journal Hippocampus, researchers studied the brains of Nile grass rats -- which, like humans, are diurnal and sleep at night -- after exposing them to dim and bright light for four weeks.
The rodents exposed to dim light lost about 30 percent of capacity in the hippocampus, a critical brain region for learning and memory and performed poorly on a spatial task they had trained on previously.
"When we exposed the rats to the dim light, mimicking the cloudy days of Midwestern winters or typical indoor lighting, the animals showed impairments in spatial learning," said Antonio "Tony" Nunez, Professor at Michigan State University in the US.
The study is the first to show that changes in environmental light, in a range normally experienced by humans, leads to structural changes in the brain, the researchers said.
The researchers mentioned that sustained exposure to dim light led to significant reductions in a substance called brain-derived neurotrophic factor -- a peptide that helps maintain healthy connections and neurons in the hippocampus -- and in dendritic spines or the connections that allow neurons to "talk" to one another.
"Since there are fewer connections being made, this results in diminished learning and memory performance that is dependent upon the hippocampus. In other words, dim lights are producing dimwits," said Joel Soler, lead author of the study.