My five year old daughter complains that she is unable to yawn. She was up most of the night a few weeks ago and only went to sleep after I gave her some Benadril, she is currently making the same complaint. I have allergies and asthma and I suspect, based on her common congestion, she might be developing the same issues. My first suspicion is that the lack of yawning might be related. That said, she s a bit intense and I would not rule out the possibility that it s an emotional response. I don t want to ignore this if it s a true medical issue.