Vitamin B12 treatment for delayed sleep phase syndrome: a multi-center double-blind study

Psychiatry Clin Neurosci. 1997 Oct;51(5):275-9. doi: 10.1111/j.1440-1819.1997.tb03198.x.


The active form of vitamin B12 (methylcobalamin) has been reported to be effective on sleep-wake rhythm disorders. Previous studies, however, were performed under open trial, and the effect of vitamin B12 has not been properly evaluated. The aim of this double-blind study was to investigate the efficacy of methylcobalamin on delayed sleep phase syndrome (DSPS). Methylcobalamin (3 mg/day) or placebo was administered for 4 weeks. The subjects were 50 patients with DSPS aged 13-55 years (26.8 +/- 1.3), 27 of whom received the active drug while 23 received the placebo. No significant differences were observed between the 2 groups in subjective evaluations of mood or drowsiness during the daytime or in night sleep by sleep-log evaluation. These results indicate that 3 mg methylcobalamin administered over 4 weeks is not an effective treatment for DSPS.

Publication types

  • Clinical Trial
  • Multicenter Study
  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Double-Blind Method
  • Female
  • Humans
  • Male
  • Middle Aged
  • Sleep Wake Disorders / drug therapy*
  • Sleep Wake Disorders / psychology
  • Vitamin B 12 / blood
  • Vitamin B 12 / therapeutic use*


  • Vitamin B 12