Working in Dim Light hurts our Ability to Remember and Learn.

Spending too much time in dimly lit rooms and offices may actually change the brain's structure and hurt one's ability to remember and learn.

In a recent study done by Michigan State University neuroscientists, researchers studied the brains of Nile grass rats [which like humans are diurnal and sleep at night] 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.

On the other hand, the rats exposed to bright light 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.

"When we exposed the rats to dim light, mimicking the cloudy days of Midwestern winters or typical indoor lighting, the animals showed impairments in spatial learning," said Antonio "Tony" Nunez, co-investigator of the study. 

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," said Joel Soler part of the research team. "In other words, dim lights are producing dimwits."

Interestingly, light does not directly affect the hippocampus, meaning it acts first other sites within the brain after passing through the eyes. 

Lily Yan, principal investigator on the project 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?

Original Source: MSUToday