There are 3 shifts of work schedule in our office for those assigned in the operation. We always notice that when an employee that was working in the graveyard shift would be assigned to the day shift, he gained weight. It is like a culture in our office that if you want to gain weight then you can ask to be assigned to graveyard because you gain weight when you lack sleep. Is that true? My take is that those in graveyard would steal some time to sleep while on duty and they again sleep at home.