We updated the design of this site on December 18, 2017. Learn more.
ClinicalTrials.gov Menu
IMPORTANT: Due to the lapse in government funding, the information on this web site may not be up to date, transactions submitted via the web site may not be processed, and the agency may not be able to respond to inquiries until appropriations are enacted. Updates regarding government operating status and resumption of normal operations can be found at opm.gov.

Effects of Vitamin B12 on the Body's Internal Clock

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
ClinicalTrials.gov Identifier: NCT00120484
Recruitment Status : Completed
First Posted : July 18, 2005
Last Update Posted : January 14, 2010
Information provided by:

Study Description
Brief Summary:
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 or disease Intervention/treatment
Sleep Disorders, Circadian Rhythm Drug: Vitamin B12

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.

Study Design

Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 10 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple (Participant, Care Provider, Investigator)
Primary Purpose: Treatment
Official Title: Effect of Vitamin B12 on the Human Circadian Pacemaker
Study Start Date : April 2005
Primary Completion Date : December 2007
Study Completion Date : January 2008

Resource links provided by the National Library of Medicine

MedlinePlus related topics: B Vitamins
U.S. FDA Resources

Arms and Interventions

Outcome Measures

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

Eligibility Criteria

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

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

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): 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
ClinicalTrials.gov Identifier: NCT00120484     History of Changes
Other Study ID Numbers: R21AT002571 ( U.S. NIH Grant/Contract )
First Posted: July 18, 2005    Key Record Dates
Last Update Posted: January 14, 2010
Last Verified: January 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