During sleep, the body slows its metabolism, meaning that many bodily functions, like the breakdown of food and use of calories, are not working as efficiently as they do while you are awake. Thus, it is possible to gain weight while you sleep. However, the weight you gain while sleeping is in the form of pure body fat. Additionally, to achieve any significant weight gain in this way, you must engage in behaviors that are not necessarily good for your health. It is always recommended that you consult your physician about the risks to your health before beginning any sort of weight-control regimen.
Sleep less. When you're not getting as much rest as you need, it puts stress on your body that causes it to store fat more efficiently. Thus, even when you are sleeping, your body is still trying to catch up and store more fat.
Eat dinner just before going to bed. Prepare something high in carbohydrates, as this increases your blood sugar rapidly and causes your pancreas to make more insulin, which helps your body to store fat. Adding foods high in fat or having juice or soda with your dinner will ensure that you have plenty of available fat.
Have a midnight snack. Wake yourself up in the middle of your sleeping schedule to have a high-calorie snack. Not only does this provide your body with extra calories that add to your weight, but it also deprives you of sleep.