It can be hormonal imbalance. This is very common specially in cases when your body is submerge in a lot of stress recently. This causes the normal function of your body to take the wrong course. Thus, you end up having weird feeling that something is wrong with your body. Yes, lack of sleep can cause you to become very hungry. Lot of people who work on night shifts easily gets hungry compared to those who have all the sleep they could have during bed times. Maybe you should stop stressing, relax and get more sleep then probably your normal body function will go back on track.