New York, May 6 (IANS): Do you find it hard to satiate your desire for food at night even after gobbling up most of what was left in the refrigerator?

This is because the same food images satisfy the brain less at night than during the day, says a new research.

Images of food, especially high-calorie food, can generate spikes in brain activity, but those neural responses are lower in the evening, the findings showed.

"You might over-consume at night because food is not as rewarding, at least visually, at that time of the day," said lead author Travis Masterson from Brigham Young University in the US.

"It may not be as satisfying to eat at night so you eat more to try to get satisfied," Masterson said.

The researchers used magnetic resonance imaging (MRI) to measure how people's brains respond to high and low calorie food images at different times of the day.

The participants viewed 360 images during two separate sessions held one week apart -- one during morning hours and one during evening hours.

They looked at images of both low-calorie foods (vegetables, fruits, fish, grains) and high-calorie foods (candy, baked goods, ice cream, fast food).

As expected, the researchers found greater neural responses to images of high-calorie foods. However, they were surprised to see lower reward-related brain reactivity to the food images in the evening.

The researchers also found that the participants were subjectively more preoccupied with food at night even though their hunger and "fullness" levels were similar to other times of the day.

The study appeared in the journal Brain Imaging and Behavior.