TORONTO (Canadian Press) -- Cutting calories and increasing physical activity aren't the only factors when it comes to losing weight and keeping it off.

Scientific studies are increasingly pointing to the role sleep -- or the lack of it -- plays in maintaining a healthy body weight.

A new commentary in the Canadian Medical Association Journal suggests inadequate sleep influences body weight in at least a couple of ways.

The article notes that people who don't get enough sleep tend to eat more at night, which undermines efforts to control one's weight or to diet.

As well, fatigue affects levels of key hormones that help the body regulate hunger.

The authors suggest people should be mindful of their sleep patterns and their potential to influence efforts to lose weight or to maintain a healthy weight.

"We know that short sleepers in general feel more hungry. And when we restrict calories in the diet of short sleepers, we know that if we already feel more hungry and you cut calories, hunger plus hunger means very hungry," says Jean-Philippe Chaput, one of the authors of the commentary.

Chaput is a specialist in preventive medicine, working on obesity in children at the Children's Hospital of Eastern Ontario, in Ottawa.

"If they want to lose weight, of course at some point they will need to cut some calories," he says.

"But if they don't take into account their sleeping patterns, they might fail. They have more chances to fail over the long term."

Still, the situation isn't as simple as saying everyone with a weight problem ought to sleep more, Chaput says.

"We know that obesity is very complex. It isn't one-size-fits-all," he says.

"People gain weight for different reasons. It's not always an increase in food intake. It can be stress. It can be depression. Genes. Different factors."

(c) The Canadian Press, 2012