The effect was seen regardless of diet, health or socio-demographic group.Sleeping too much or too little can increase the likelihood of becoming obese, researchers have discovered.
The study found abnormal sleeping patterns increased the risk of being overweight for those genetically predisposed to obesity.
The effect was seen regardless of diet, health or socio-demographic group.
The University of Glasgow study also found no clear link between sleep duration and body weight in those with a low genetic risk of obesity.
Researchers looked at the effects of a short sleep of less than seven hours a night and a long sleep more than nine hours along with daytime napping and shift work.