Hi...., Yawning excessively may indicate a sleep disorder, such as sleep apnea, that results in a lack of restorative sleep. Yawning excessively may also be your body’s reaction to a change in daily habits or work hours, such as taking on a night-shift job or working longer hours... If you have hypothyroidism or electrolyte imbalances, you may also feel drowsy during waking hours, which could also trigger excessive yawning....Consult Physician....