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One reason you can't stop snacking late at night

Brains are less stimulated by food at night, a Brigham Young University study shows. And that, ironically, is exactly what leads to those midnight food cravings.

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Basking in the glow...of the refrigerator. Brigham Young University

Ever find yourself standing in front of an open fridge at 3 in the morning with an unmistakable urge to cram cold chicken, layer cake and what you hope is leftover meatloaf in your face until your mouth can't hold another morsel?

Many human beings with a working stomach know the familiar urge for midnight feasting, but may not understand why that late-night nibble is so likely to become a feeding frenzy. According to new research, your brain activity (and by extension the rest of you) is less easily stimulated by food at night than earlier in the day. And, well, you eat to compensate.

Researchers at Brigham Young University in Utah found that brain activity is lower in response to images of food later in the day, and the drive we have to snack at night may be our attempt to increase those diminishing "food high" brain spikes. The results of the study were published in the medical journal Brain Imaging and Behavior in March, but the university officially released information on the research Tuesday.

Researchers examined the brain activity of 15 healthy women through magnetic resonance imaging, or MRI, as participants looked at 360 pictures of different types of food during two separate sessions, one in the morning and the other in the evening. The subjects were shown pictures of healthier foods like fruits and vegetables and then higher-calorie fast foods. Naturally, their brains responded more to the foods they knew they probably shouldn't eat because, well, you don't need to be a scientist to know that ice cream always beats kale.

The results, however, showed that participants' brains responded differently to those foods depending on the time of day. Those who examined the pictures during morning hours generated more "spikes in brain activity," while those who examined them during evening hours generated significantly fewer spikes, regardless of what the images showed. However, the people in the study showed signs that they were subjectively more preoccupied with food in the latter stages of the day, according to the study.

These responses may explain why we tend to munch late at night. Travis Masterson, who led the study as his thesis for a master's degree in exercise science, said in a statement that people might be eating more at night "because food is not as rewarding, at least visually, at that time of day. It may not be as satisfying to eat at night so you eat more to try to get satisfied."

The research involved a small sample, and the results still need further study, but if the results are correct, your brain isn't necessarily telling you to eat more at night. You are trying to tell your brain to give you that satisfying feeling when you overeat after midnight. It's a classic case of the tail wagging the dog except the dog is your brain and the tail is your need to eat Nutella straight out of the jar.