NCT01119365

Brief Summary

Light is the primary means by which the internal circadian clock remains aligned ("entrained") with the external world. Misalignment of this internal clock can occur during situations such as shift work and jet travel across multiple time zones (jet lag). The purpose of this study is to examine how sequences of brief flashes of light can affect entrainment of the clock.

Trial Health

43
At Risk

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Trial has exceeded expected completion date
Enrollment
300

participants targeted

Target at P75+ for not_applicable healthy

Timeline
Completed

Started Jul 2011

Longer than P75 for not_applicable healthy

Geographic Reach
1 country

1 active site

Status
unknown

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

Click on a node to explore related trials.

Study Timeline

Key milestones and dates

First Submitted

Initial submission to the registry

May 5, 2010

Completed
2 days until next milestone

First Posted

Study publicly available on registry

May 7, 2010

Completed
1.2 years until next milestone

Study Start

First participant enrolled

July 1, 2011

Completed
11.9 years until next milestone

Primary Completion

Last participant's last visit for primary outcome

June 1, 2023

Completed
Same day until next milestone

Study Completion

Last participant's last visit for all outcomes

June 1, 2023

Completed
Last Updated

April 6, 2022

Status Verified

March 1, 2022

Enrollment Period

11.9 years

First QC Date

May 5, 2010

Last Update Submit

March 28, 2022

Conditions

Healthy

Keywords

Healthy controls

Outcome Measures

Primary Outcomes (1)

  • Circadian phase

    The timing of the onset of melatonin is compared before and after a light stimulus

    2 days

Secondary Outcomes (1)

  • Alertness

    1 hour

Study Arms (1)

Light

EXPERIMENTAL

Sequence of bright light flashes of varying durations, interflash intervals, flash lengths, flash brightness, and flash color.

Other: Bright light

Interventions

Bright lightOTHER

Light is administered through a custom designed mask with LED lights.

Light

Eligibility Criteria

Age18 Years - 35 Years
Sexall
Healthy VolunteersYes
Age GroupsAdult (18-64)

You may qualify if:

  • Good health
  • Normal hearing

You may not qualify if:

  • Sleep disorder
  • Extreme chronotype
  • Regular smoker
  • Depression
  • Alcohol abuse
  • Illegal drug use

Contact the study team to confirm eligibility.

Sponsors & Collaborators

Study Sites (1)

VA Palo Alto Health Care System

Palo Alto, California, 94304, United States

RECRUITING

Related Publications (7)

  • Zeitzer JM, Dijk DJ, Kronauer R, Brown E, Czeisler C. Sensitivity of the human circadian pacemaker to nocturnal light: melatonin phase resetting and suppression. J Physiol. 2000 Aug 1;526 Pt 3(Pt 3):695-702. doi: 10.1111/j.1469-7793.2000.00695.x.

    PMID: 10922269BACKGROUND

  • Cajochen C, Zeitzer JM, Czeisler CA, Dijk DJ. Dose-response relationship for light intensity and ocular and electroencephalographic correlates of human alertness. Behav Brain Res. 2000 Oct;115(1):75-83. doi: 10.1016/s0166-4328(00)00236-9.

    PMID: 10996410BACKGROUND

  • Zeitzer JM, Khalsa SB, Boivin DB, Duffy JF, Shanahan TL, Kronauer RE, Czeisler CA. Temporal dynamics of late-night photic stimulation of the human circadian timing system. Am J Physiol Regul Integr Comp Physiol. 2005 Sep;289(3):R839-44. doi: 10.1152/ajpregu.00232.2005. Epub 2005 May 12.

    PMID: 15890792BACKGROUND

  • Zeitzer JM, Ruby NF, Fisicaro RA, Heller HC. Response of the human circadian system to millisecond flashes of light. PLoS One. 2011;6(7):e22078. doi: 10.1371/journal.pone.0022078. Epub 2011 Jul 8.

    PMID: 21760955RESULT

  • Zeitzer JM, Fisicaro RA, Ruby NF, Heller HC. Millisecond flashes of light phase delay the human circadian clock during sleep. J Biol Rhythms. 2014 Oct;29(5):370-6. doi: 10.1177/0748730414546532. Epub 2014 Sep 16.

    PMID: 25227334RESULT

  • Najjar RP, Zeitzer JM. Temporal integration of light flashes by the human circadian system. J Clin Invest. 2016 Mar 1;126(3):938-47. doi: 10.1172/JCI82306. Epub 2016 Feb 8.

    PMID: 26854928RESULT

  • Joyce DS, Spitschan M, Zeitzer JM. Duration invariance and intensity dependence of the human circadian system phase shifting response to brief light flashes. Proc Biol Sci. 2022 Mar 9;289(1970):20211943. doi: 10.1098/rspb.2021.1943. Epub 2022 Mar 9.

    PMID: 35259981RESULT

Study Officials

  • Jamie M Zeitzer, PhD

    Stanford University/VAPAHCS

    PRINCIPAL INVESTIGATOR

Central Study Contacts

Marisol Duran

CONTACT

650-493-5000mreinoso@pavir.org

Study Design

Study Type
interventional
Phase
not applicable
Allocation
RANDOMIZED
Masking
DOUBLE
Who Masked
INVESTIGATOR, OUTCOMES ASSESSOR
Masking Details
The investigator is unaware of specific sequence of light that is given to the participant until all data are analyzed.
Purpose
BASIC SCIENCE
Intervention Model
SINGLE GROUP
Sponsor Type
FED
Responsible Party
PRINCIPAL INVESTIGATOR
PI Title
Associate Professor

Study Record Dates

First Submitted

May 5, 2010

First Posted

May 7, 2010

Study Start

July 1, 2011

Primary Completion

June 1, 2023

Study Completion

June 1, 2023

Last Updated

April 6, 2022

Record last verified: 2022-03

Locations

US(1)