(by Giovanni Calcerano) People who suffer from seasonal affective disorders are well aware that lighting can influence mood and emotions, for better or for worse. But what hasn't been clear so far is that enlightenment can also heavily affect cognition. In fact, according to research by neuroscientists at Michigan State University, spending too much time in dimly lit rooms or offices could change the structure of the brain and damage the ability to remember and learn. And, again for the same research, the opposite would also seem true: bright and marked lights can improve the ability to memorize information.
To arrive at these results, the researchers studied the brains of Nile grass rats (which, like humans, are diurnal and sleep at night) after exposing them to soft and bright light for four weeks. Rodents exposed to dim light have lost about 30% of the faculties of the hippocampus, that is to say that region of the brain essential for learning and memory, and have also obtained a marked deterioration in the performance of a spatial task for which they were previously trained. According to Professor Tony Nunez, one of the authors of the study, what they found is similar to what happens to people when they can't find their cars in the parking lot after spending a few hours in a shopping mall or cinema.
Rats exposed to intense light, on the contrary, showed significant improvement in the performance of the same spatial exercise. Moreover, when the rodents previously exposed to the dim light were, after a month's break, exposed to intense light for another four weeks, they completely regained their brain capacity and were again able to complete the task correctly.
This study, funded by the National Institutes of Health, is the first to concretely demonstrate that changes in ambient light lead to structural changes in the brain. According to Joel Soler, PhD student in psychology and co-author of the study, prolonged exposure to low-intensity light leads to significant reductions in a substance called "brain-derived neurotrophic factor," a peptide that helps maintain healthy connections and neurons in the brain. hippocampus, and also to the reduction of the dendritic spines, ie those connections that allow neurons to "talk" with each other.
"Since there are fewer active connections, this translates into a reduction in learning ability and memory performance," Soler said. "In other words, low lighting creates stupidity."
Interestingly, light does not affect the hippocampus directly as, after passing the eyes, it first passes through other sites in the brain. Based on this, then, the research team is focusing their attention on a particular site in the rodent brain, specifically a group of neurons in the hypothalamus that produces a peptide called orexin. This orexin is known to affect a wide variety of brain functions and therefore appears to be the cause of the improvement or worsening of cognitive performance. The hypothesis that will therefore have to be tested is whether the administration of orexin to rats exposed to weak light will allow their brains to recover without being exposed to bright light again.
If this is the case, it could have significant implications for the elderly and for people with glaucoma or retinal degeneration. In fact, it would be sufficient to directly manipulate the group of neurons in the brain, bypassing the eye, and therefore provide these people with the same benefits of exposure to bright light.
In any case, the research clearly suggests that the design of the spaces in which we live has a strong direct impact on our way of acting and thinking. Given that, on average, we spend 90% of our time indoors, it is therefore absolutely essential to design houses and offices in order to have a great deal of natural light.