Effects of Vitamin B12 on the Body's Internal Clock

This study has been completed.
Information provided by:
Brigham and Women's Hospital
ClinicalTrials.gov Identifier:
First received: July 13, 2005
Last updated: January 12, 2010
Last verified: January 2010

July 13, 2005
January 12, 2010
April 2005
December 2007   (final data collection date for primary outcome measure)
Change in circadian period [ Time Frame: first 2 weeks vs. final 2 weeks of period assessments ] [ Designated as safety issue: No ]
Change in circadian period
Complete list of historical versions of study NCT00120484 on ClinicalTrials.gov Archive Site
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Effects of Vitamin B12 on the Body's Internal Clock
Effect of Vitamin B12 on the Human Circadian Pacemaker

Circadian rhythms are 24-hour cycles that influence natural functions in the body such as heart rate, blood pressure, and body temperature. Circadian rhythms provide the body with an internal clock and affect sleep patterns. The purpose of this study is to determine the effects of vitamin B12 supplements on circadian rhythms and sleep-wake regulation.

Individuals with circadian rhythm sleep disorder suffer from recurrent patterns of disrupted sleep that can significantly affect their daily functioning. Evidence suggests that vitamin B12 supplements may have a beneficial effect on sleep patterns. However, research on the effects of vitamin B12 supplements on sleep is limited. This study will determine the effects of vitamin B12 supplements on circadian rhythms and sleep-wake regulation.

This study will last 47 days. Participants will undergo a 3-week medical and psychological screening prior to study entry. Eligible participants will be admitted to the General Clinical Research Center where they will live in a private study room for the duration of the study. The room will be a time-free environment with no windows, clocks, television, or radio. Participants will not be able to make or receive telephone calls, and their bedtimes, wake times, and mealtimes will be determined by study researchers. Participants will be randomly assigned to receive three capsules of either vitamin B12 or placebo daily. Blood and saliva collection will occur daily to determine core body temperature and hormone levels. Performance tests to determine participants' cognitive abilities will be administered at regular intervals throughout each day. Participants' sleep will be recorded every night with polysomnography, which will monitor brain and muscle activity and breathing patterns during sleep.

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Allocation: Randomized
Endpoint Classification: Bio-equivalence Study
Intervention Model: Parallel Assignment
Masking: Double Blind (Subject, Caregiver, Investigator)
Primary Purpose: Treatment
Sleep Disorders, Circadian Rhythm
Drug: Vitamin B12
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*   Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline.
January 2008
December 2007   (final data collection date for primary outcome measure)

Inclusion Criteria:

  • Diagnosis of delayed sleep phase syndrome OR self-described as a "night owl"

Exclusion Criteria:

  • History of medical illness
  • History of psychiatric illness in participant or his or her family members
  • Current medication or vitamin use
  • Follow a vegan diet
  • Significant visual problem
  • Recent travel across time zones
  • History of rotating shiftwork
18 Years to 30 Years
Contact information is only displayed when the study is recruiting subjects
United States
R21 AT002571, R21AT002571
Jeanne F. Duffy, Brigham and Women's Hospital
Brigham and Women's Hospital
National Center for Complementary and Integrative Health (NCCIH)
Principal Investigator: Jeanne F. Duffy, PhD Brigham and Women's Hospital, Harvard Medical School
Brigham and Women's Hospital
January 2010

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP