It can be a symptom of brain lesions, haemorrhage, motion sickness and encephalitis. On the other hand, it has been reported that psychotics rarely yawn, except those suffering from brain damage. Interestingly, some clinicians claim that those with acute physical illness don't yawn until they are on road to recovery. But what is currently known about yawning is essentially anecdotal, mostly because the yawn has not got the respect it deserves.