I have had this be for but it always seemed to happen when I was super fatigued, either from lack of sleep or else a side effect of my anxiety/panic attacks. when I was I wellbutrin I had it all the time. it was like I couldn't yawn all the way if that makes since.really annoying. I would definitely talk to your doctor about some kind of relaxation techniques. or maybe get a sleep study done, and that's causing fatigue? good luck. and hope you feel better