If you're struggling to lose weight, scientists say you might want to assess your sleeping habits.
Researchers from the Eastern Ontario Research Institute and Laval University in Canada say a good night's sleep could be just as important as diet and exercise.
They say seven hours' shut-eye is the minimum adults should be getting if they want to improve their odds of losing weight on a diet.
Recent research found lack of sleep prompts hormones in our brains to increase our appetite and make us eat more.
Now the Canadian scientists are calling for medical practitioners to address people's sleep habits alongside their diet and exercise levels.
"The solution to weight loss is not as simple as 'eat less, move more, sleep more,'" Dr Jean-Phillippe Chaput and Dr Angelo Tremblay wrote in the Canadian Medical Association Journal.
"However, an accumulating body of evidence suggests that sleeping habits should not be overlooked when prescribing a weight-reduction program to a patient with obesity. Sleep should be included as part of the lifestyle package that traditionally has focused on diet and physical activity."
One experiment found people who changed their sleep habits from six hours to between seven and eight hours put on 2.4kg less after six years.
Another study got one group of people to sleep for five hours a night and another to sleep for eight-and-a-half hours a night for two weeks while consuming a low fat diet.
The researchers found those with less sleep burnt muscle and stored their fat, while those who clocked eight hours' sleep lost 55 percent more body fat and 60 percent more muscle over the fortnight.
Georgina Heath, a PhD student at the University of South Australia's Centre for Sleep Research, told ninemsn that a lack of sleep can influence eating behaviour.
"We have done a study here in the lab that suggested people who get short sleep tended to opt for sweet snacks and they snacked more than people who were getting more sleep than them," she said.
"Now we need to start looking at why people are doing that."
Heath says Australians should aim for between seven and nine hours sleep between the hours of 10pm and 7am.
"That's in line with the circadian rhythm," she said.
Professor Leslie Campbell, director of diabetes services at St Vincent's hospital in Sydney, told ninemsn that our bodies use light and dark to regulate our hunger hormones.
"Light-dark is the regulator of our sleep-wake cycles," she said
"We usually spend all night asleep and we don't get hungry but if you go 12 hours in the day without eating, you get hungry. There is an off switch at night and if you don't obey that, you muck it up."
As a result, Professor Campbell said a lot of people who don't sleep at night end up overeating, which can lead to obesity.
"One study found up to 25 percent of obese people eat at night – it's a big contributor," she said.