Dusk, moonlight, a cozy fireplace light — undoubtedly, all of these evoke a romantic mood, but according to a new study, there’s more to dim light than meets the eye. Turns out, there might be an additional reason why a dim-lit setting leads us to make (sometimes poor) romantic decisions.

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Dim light affects our judgment in mysterious ways…

We’ve all been there at some point: you’re on a date in a dimly lit, cozy little restaurant.

It’s going reasonably well, and the person you’re with is half decent. However, maybe they’re not as attractive as you’d like, or perhaps they’re kind of rude to the waiter, or maybe they make weird chewing noises. Either way, you decide they’re not the right person for you.

Buuut, as you’re there, you might as well relax and try to enjoy the evening. You have a glass of wine, maybe two, one thing leads to another and let’s just say…the evening ends wildly differently from what you initially intended.

The next morning, as you watch your…unforeseen and premature partner sleeping, you begin to wonder, “What on earth were you thinking? What led to this…poor romantic choice? Was it the wine? Was it the atmosphere? Could it have been…the light?!”

According to a new study, yes, it could very well have been the light (although in our little scenario, the wine probably didn’t help either). Sure, a dim and romantic light makes us all look a little more attractive than we do in the cruel light of day, but — the new research seems to suggest — when you chose to go home with that person, you may have been…cognitively impaired.

Researchers at Michigan State University in East Lansing tested the cognitive abilities of a type of rat that sleeps at night and is awake during the day — just like humans are.

The scientists exposed the rodents to dim light and bright light for a period of 4 weeks. Their new findings — published in the journal Hippocampus — may make you think twice before you light up that candle.

The rats that had been exposed to dim light performed poorly on spatial learning tasks and showed a 30 percent decrease in their hippocampi, which is a brain area that is key to learning and forming new memories.

Also, the same rodents showed decreased levels of a brain peptide that normally helps neurons to communicate with one another in the hippocampus. The peptide, which is called a brain-derived neurotrophic factor, contributes to keeping healthy connections between neurons.

“Since there are fewer connections being made,” explains lead study author Joel Soler, a doctoral graduate student in psychology, “this results in diminished learning and memory performance that is dependent upon the hippocampus.”

“In other words,” he adds, “dim lights are producing dimwits.”

Conversely, rodents that were exposed to very bright light seemed to be, well, brighter; these rodents performed much better on spatial orientation tasks.

Additionally, when the “dim” rats were returned to bright light for another 4 weeks and then tested again, their brain capacity and cognitive performance had returned to normal.

This marks the first time that a study has shown that environmental changes in the light could lead to structural changes in the brain.

“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,” says study co-author Antonio Núñez, a professor of psychology.

He continues, saying, “This is similar to when people can’t find their way back to their cars in a busy parking lot after spending a few hours in a shopping mall or movie theater.” Or…similar to when people can’t find their way to their own bed after spending a few hours on a dimly lit date.