The study proposes to investigate whether sleep deprivation will affect a variety of measures, including hormones, immune system functioning, and behaviors related to food intake and hunger. It is predicted that sleep deprivation will affect circulating neutrophil activity, and do so via affects on DNA methylation. It is also predicted that sleep deprivation will up-regulate ghrelin, and down-regulate circulating oxytocin. Finally, it is predicted that sleep deprivation will increase participants' tendencies to pick larger portions of food, and also increase their tendency to purchase foods that are more caloric in a mock supermarket scenario.