Treatment of recurrent hypersomnia with methylcobalamin (vitamin B12): a case report.

A 32 year old male patient suffered from recurrent hypersomnia for 12 years was successfully treated with vitamin B12. Episodes of hypersomnia lasting a few days occurred repeatedly a few times each year. Furthermore, the frequency of episodes had increased during the last 2 years. During the administration of vitamin B12, the patient had no episodes of hypersomnia for 6 months. In addition, he did not have any episodes during a follow-up observation period of 17 months after cessation of the treatment. Thus, this case suggests that vitamin B12 may be effective for preventing recurrent hypersomnia.