Lack of sufficient sleep combined with free access to food increases calorie consumption and consequently fat accumulation, especially unhealthy fat inside the belly, shows the latest research from Mayo Clinic. Findings from a randomised controlled crossover study led by Dr Naima Covassin, a cardiovascular medicine researcher at Mayo Clinic, show that lack of sufficient sleep led to a 9 percent increase in total abdominal fat area and an 11 percent increase in abdominal visceral fat, compared to control sleep. Visceral fat is deposited deep inside the abdomen around internal organs and is strongly linked to cardiac and metabolic diseases. The findings are published in the Journal of the American College of Cardiology, and the study was funded by the National Heart, Lung and Blood Institute.