Being an early riser could increase the risk for having anorexia nervosa -- an eating disorder characterised by low weight, food restriction, body image disturbance, fear of gaining weight. The study found that having anorexia nervosa could lead to an earlier wake time. It also revealed a link between anorexia nervosa and insomnia risk.

Published in JAMA Network Open, the study showed anorexia nervosa is based on rising early, unlike many other disorders that tend to be evening-based such as depression, binge eating disorder and schizophrenia.