I am yawning excessively. what can this be?

Need better sleep: Yawning, first of all, is suggestible, so it sometimes can come from thinking about it or seeing other people's yawning. More commonly, though, spontaneously, it is the result of drowsiness, fatigue. Perhaps you are not getting adequate sleep or adequately restful sleep. Here's a good article http://www.Localhealth.Com/article/yawning-excessively.