A new study has shown how spending too much time in dimly lit rooms and offices may have a negative impact on a person’s brain to the point that it may hurt their ability to remember and learn.
Researchers at Michigan State University studied the brains of Nile grass rats after exposing them to dim and bright light for four weeks. The rodents exposed to dim light lost about 30 per cent 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.
The rats exposed to bright light, on the other hand, showed significant improvement on the spatial task. Further, when the rodents that had been exposed to dim light were then exposed to bright light for four weeks (after a month-long break), their brain capacity – and performance on the task – recovered fully.
The study can be considered a first of its kind that shows that changes in environmental light, in a range normally experienced by humans, leads to structural changes in the brain. Americans, on average, spend about 90 percent of their time indoors, according to the Environmental Protection Agency.
Researchers said 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.
Interestingly, light does not directly affect the hippocampus, meaning it acts first other sites within the brain after passing through the eyes. Yan said the research team is investigating one potential site in the rodents’ brains – a group of neurons in the hypothalamus that produce a peptide called orexin that’s known to influence a variety of brain functions. One of their major research questions: If orexin is given to the rats that are exposed to dim light, will their brains recover without being re-exposed to bright light?
The project could have implications for the elderly and people with glaucoma, retinal degeneration or cognitive impairments.