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Effects of Vitamin B12 on the Body's Internal Clock

This study has been completed.
National Center for Complementary and Integrative Health (NCCIH)
Information provided by:
Brigham and Women's Hospital Identifier:
First received: July 13, 2005
Last updated: January 12, 2010
Last verified: January 2010
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.

Condition Intervention
Sleep Disorders, Circadian Rhythm
Drug: Vitamin B12

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double Blind (Participant, Care Provider, Investigator)
Primary Purpose: Treatment
Official Title: Effect of Vitamin B12 on the Human Circadian Pacemaker

Resource links provided by NLM:

Further study details as provided by Brigham and Women's Hospital:

Primary Outcome Measures:
  • Change in circadian period [ Time Frame: first 2 weeks vs. final 2 weeks of period assessments ]

Enrollment: 10
Study Start Date: April 2005
Study Completion Date: January 2008
Primary Completion Date: December 2007 (Final data collection date for primary outcome measure)
Detailed Description:

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.


Ages Eligible for Study:   18 Years to 30 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

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
  Contacts and Locations
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Please refer to this study by its identifier: NCT00120484

United States, Massachusetts
Brigham and Women's Hospital, Harvard Medical School
Boston, Massachusetts, United States, 02115
Sponsors and Collaborators
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
  More Information

Responsible Party: Jeanne F. Duffy, Brigham and Women's Hospital Identifier: NCT00120484     History of Changes
Other Study ID Numbers: R21AT002571 ( US NIH Grant/Contract Award Number )
Study First Received: July 13, 2005
Last Updated: January 12, 2010

Keywords provided by Brigham and Women's Hospital:
Circadian Rhythm
Biological Clock
Complementary and Alternative Medicine

Additional relevant MeSH terms:
Sleep Disorders, Circadian Rhythm
Sleep Wake Disorders
Nervous System Diseases
Neurologic Manifestations
Signs and Symptoms
Mental Disorders
Chronobiology Disorders
Occupational Diseases
Vitamin B 12
Vitamin B Complex
Growth Substances
Physiological Effects of Drugs
Hematinics processed this record on May 25, 2017