Hypnic Myoclonia is a sudden muscle contraction which occurs at the transition from sleep to awakening and is observed in about 60-70% of people of all age groups. A case of a male infant who had repetitive bleeding and ulceration of the tongue following tongue biting due to Hypnic Myoclonia is reported. He began to experience myoclonus with a bite wound of the tongue and severe screaming when he was 10 months old. For palliative care, we smoothed the cutting edge of the maxillary-mandibular primary incisors and made an impression to produce a removable resin appliance to be applied while sleeping. Symptomatic improvement did not take place, and we asked a pediatrician of the university hospital in Fukuoka to examine the patient. The Results of the medical examinations showed no abnormality, and also no abnormality on the-electroencephalogram of the head, and magnetic resonance imaging. Hypnic Myoclonia with physiological abnormality was diagnosed. Irrigation, gargling with AZ fine granules and laser-treatment for the bleeding and ulceration region were undertaken. After we instructed the patient to cover the affected area with a towel while sleeping,5 months later the symptoms improved with decreased frequency of tongue biting, and this mostly disappeared at the age of 1 year and 8 months.
We considered this phenomenon to be an age-dependent phenomenon related to the maturation of the brain and to the development of the oral functions because it disappeared spontaneously at age of 1 year and 8 months.