Restricted sleep has been linked to obesity but the underlying mechanisms are not clear. This study aimed to assess whether restricted sleep (4.5hrs for 4 consecutive nights) alters the appetite-regulating hormones ghrelin, leptin and pancreatic polypeptide in the following 24hrs in 19 healthy, lean men (BMI 19-24.9). This randomised crossover study assessed whether those hormonal changes predicted the food intake during ad libitum feeding. The study found that Ghrelin levels were increased after sleep restriction but did not alter leptin or pancreatic polypeptide profiles. Sleep restriction was associated with an increase in calorie consumption from snacks, primarily from carbohydrates. They concluded that restricted sleep significantly increases ghrelin levels. Elevated ghrelin is associated with an increased calorie consumption which may lead to the development of obesity.