If you’re having trouble losing weight, it could be because you’re not sleeping enough.

Scientists have discovered that you can double your chances of achieving your weight loss goal if you get between six and eight hours of sleep a night.

Any more than that is too inactive and any less increases stress levels and increases cravings for unhealthy food, the study suggests.

People trying to lose at least 10 pounds were more likely to reach that goal if they had lower stress levels and slept moderately.

Nearly 500 adults took part in the study by Kaiser Permanente, in Portland, USA, with an average age of 55 and all of whom suffered from obesity.

Getting a healthy amount of sleep, avoiding stress and following a weight-loss plan (such as keeping a food diary) seem to boost the odds of success, according to a new study.

Those involved in the study were asked to attend counseling sessions, cut 500 calories a day and exercise at least three hours a week. They also had to keep a diary of their habits including sleep patterns and stress levels.

After six months, 60 per cent of the participants had lost at least 10 pounds.  The successful dieters were more likely to report that they slept between six and eight hours each night.

Almost three quarters of dieters who had both low stress levels and six to eight hours sleep a night were likely to achieve the 10 pound weight loss target.  They were also twice as likely to be successful as participants who reported the highest stress levels and got six or less hours sleep a night.

The study is published in the International Journal of Obesity.