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Does dusk keep us stupid?


Permanent dim light affects the brain of rats

Light can have a massive impact on health and mood. "It's good to talk in the dark," the saying goes, but in a recent study, scientists suggest that permanent twilight can damage the brain. The researchers are investigating the influence that too little light has on the brain and brain power in diurnal rats. The rodents were exposed to dim light for weeks, which reduced their ability to learn and remember. The scientists now suspect that this can also be the case for people who spend too much time in poorly lit rooms and offices.

The researchers examined the brains of Nile grass rats, which like humans are active during the day and sleep at night. The rodents were exposed to weak light for four weeks. During this period, the rats lost approximately 30 percent of their capacity in the hippocampus. This brain region is responsible for learning and memory. The rats showed a significantly poorer performance when solving an already trained spatial task than before the influence of the twilight. The research team led by Joel Soler from Michigan State University in East Lansing recently published their study results in the journal "Hippocampus".

A light cure negated the changes

A control group of rats was exposed to bright light. This group achieved significantly higher performances on the same task. The animals, which were previously exposed to the bad light, also recovered completely from their reduced brain capacity through a four-week light cure and brought full performance to the task again.

Why people can no longer find their cars

This is the first study of its kind to show that changes in ambient light can lead to structural changes in the brain. If these findings are confirmed in humans, this could have massive consequences. On average, Americans spend 90 percent of their time indoors, according to the Environmental Protection Agency. The psychology professor and researcher in the study Antonio Nunez compares the results in the rats with behavior in humans: "It is similar to the fact that after a stay of several hours in a shopping center or a cinema in a busy parking lot, people cannot find their way back to their cars."

Dim light creates stupidity

Joel Soler, doctor of psychology and lead author of the study, explains that the weak light leads to a decrease in a peptide in the brain, which helps to maintain healthy connections and neurons in the hippocampus. “Because fewer connections are made, this leads to reduced learning and memory performance, which depends on the hippocampus,” Soler explains in a press release from the university on the study results. "In other words, dim light creates stupidity," says Soler.

The results enable new approaches

The researchers discovered a possible location in the rodents' brains that produce a peptide called orexin, which is known to affect a variety of brain functions. In further studies, the scientists want to clarify whether orexin administration in rats exposed to poor light leads to their brains recovering.

New therapies for neurological diseases?

The project could also affect the elderly and people with glaucoma, retinal degeneration or cognitive impairment. Further investigations will determine whether orexin administrations are suitable for improving cognitive functions in the aging population and for reversing neurological diseases or preventing progression. (vb)

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