Losing weight - especially from around your waist - may significantly improve your sleep quality, US scientists have found.
People who lose around 6 kg in weight - and reduced their waistline by around 15 per cent slept much better, according to researchers from Johns Hopkins University.
On the other hand, those who are overweight or obese will continue to have problems, the Daily Mail reported.
The study enrolled 77 people who had type 2 diabetes or pre-diabetes. The participants, all of whom were also overweight or obese, were randomly assigned to one of two groups.
One group went on a diet and had supervised exercise training, while the other group only had the diet intervention.
The participants filled out a sleep survey at the beginning and end of the study to identify sleep problems, including sleep apnoea, daytime fatigue, insomnia, restless sleep, excessive sleep or sleepiness and use of sedatives to aid sleep.
Their body mass index and amount of abdominal fat were also measured at the start and end of the study.
Both groups lost about 7 kg of weight, on average.
They also lost about the same amount of belly fat, which was assessed by magnetic resonance imaging.
Although a variety of sleep problems were reported by the participants, none stood out as being the most common, so the researchers analysed a composite score, which reflects overall sleep health.
They found that both groups improved their overall sleep score by about 20 per cent, with no differences between the groups.
"We found that improvement in sleep quality was significantly associated with overall weight loss, especially belly fat," said Kerry Stewart, professor of medicine at the Johns Hopkins University School of Medicine and director of clinical and research exercise physiology.
"This was true no matter the age or gender of the participants or whether the weight loss came from diet alone or diet plus exercise," said Stewart.