Light Timing Study

NCT04753190 | Recruiting

• 1 other identifier: R01HL151512
• Study Type: interventional
• Target: 113
• Locations: 1 country
• Sites: 1

Brief Summary

Chronic circadian misalignment and sleep restriction peak during late adolescence, and are associated with morning daytime sleepiness, poor academic performance, conduct problems, depressed mood, suicidal ideation, substance use, insulin resistance, and obesity. Bright light exposure from light boxes can shift rhythms earlier (phase advance) to facilitate earlier sleep onset and reduce morning circadian misalignment and the associated risks. To phase advance circadian rhythms, the investigators' PRCs showed that the ideal time to begin light exposure was slightly before wake-up time and light should be avoided around bedtime because this is when light produces maximum phase delay shifts. An unexpected finding from these results, however, was a second advancing region in the afternoon (\~6 to 9 h after habitual wake-up time) suggesting that afternoon light may have more circadian phase advancing ability than traditionally thought. The overall goal of this mechanistic study is to follow-up on the unexpected PRC findings and test whether individually-timed afternoon light alone and in combination with morning bright light can shift circadian rhythms earlier in older adolescents. Four groups will be compared in a randomized parallel group design: afternoon bright light, morning bright light, morning + afternoon bright light, and a dim room light control. Adolescents will complete a 2-week protocol. After a baseline week with a stable sleep schedule, adolescents will live in the laboratory for 7 days. Sleep/dark and the time of bright light exposure will gradually shift earlier. Bright light (\~5000 lux) will be timed individually based on his/her stable baseline sleep schedule. The first 3-h morning bright light exposure will begin 1 h before wake on the first morning. The first 3-h afternoon bright light exposure will begin 5 h after wake. The morning + afternoon exposures will begin at the same times, but each exposure will be 1.5 h so that a total of 3 h of bright light per day will be given to each group except the dim light control group. Phase shifts of the circadian clocks marked by the dim light melatonin onset (DLMO) is the main outcome. Investigators hypothesize that afternoon bright light will work synergistically with morning bright light to produce larger shifts than morning or afternoon bright light alone. These data could challenge the current understanding of how to use bright light to shift circadian rhythms earlier.

Conditions

Chronobiology; Light; Sleep; Circadian Rhythm; Adolescence

Keywords

Sleep; Circadian Rhythm; Adolescence

Outcome Measures

Primary Outcomes (1)

• Dim Light Melatonin Onset (DLMO) Phase Shift Change

  Saliva sampling for the baseline DLMO will begin 6 hours before baseline bedtime and end 2 hours after baseline bedtime to capture the rise of endogenous melatonin. Sampling for the final DLMO will begin 7 hours before baseline bedtime and end 2 hours after baseline bedtime. Participants remain awake and seated in comfortable recliners in dim light (\< 5 lux), except when they need to use the adjoining restroom (also \< 5 lux). Saliva samples are collected every 30 minutes using Salivettes, The samples are immediately centrifuged and frozen, and later shipped on dry ice to SolidPhase, Inc. (Portland, ME), where they are analyzed for melatonin using direct radioimmunoassay (RIA). We compute the DLMO using a 4 pg/mL threshold; the time at which melatonin values surpass this threshold is the DLMO. Baseline - Final DLMO will define the phase shift change of the central circadian clock.

  Change in DLMO phase from baseline (day 8) to final phase assessment (day 13)

Study Arms (4)

Dim Room Light Control

PLACEBO COMPARATOR

Participants in the dim room light control group will not receive any bright light exposure.

Behavioral: Baseline Sleep Satiation and Phase Stabilization; Behavioral: Gradually Shifted Sleep

Morning Bright Light Only (MBL)

EXPERIMENTAL

Participants in the morning bright light (MBL) group will receive a 3-h bright light exposure from 2 light boxes on 3 consecutive mornings in the laboratory. Bright light will be timed for each individual based on their baseline sleep schedule to shift the circadian timing system earlier ("phase advance").

Behavioral: Baseline Sleep Satiation and Phase Stabilization; Behavioral: Gradually Shifted Sleep

Afternoon Light Only (ABL)

EXPERIMENTAL

Participants in the afternoon bright light (ABL) group will receive a 3-h bright light exposure from 2 light boxes on 3 consecutive afternoons in the laboratory. Bright light will be timed for each individual based on their baseline sleep schedule to shift the circadian timing system earlier ("phase advance").

Behavioral: Baseline Sleep Satiation and Phase Stabilization; Behavioral: Gradually Shifted Sleep

Morning + Afternoon Light (MBL+ ABL)

EXPERIMENTAL

Participants in the morning bright light + afternoon bright light (MBL+ ABL) group will receive bright light from 2 light boxes on 3 consecutive days in the laboratory. The morning exposure will be 1.5 h and the afternoon exposure will be 1.5 h. Bright light exposures will be timed for each individual based on their baseline sleep schedule to shift the circadian timing system earlier ("phase advance").

Behavioral: Baseline Sleep Satiation and Phase Stabilization; Behavioral: Gradually Shifted Sleep

Interventions

Baseline Sleep Satiation and Phase Stabilization BEHAVIORAL

All participants will be assigned a 9-h sleep opportunity for the first week of the 2-week study. This will ensure that adolescents are not sleep restricted before living in the laboratory during the second week of the study. The 9-h sleep schedule will be individually timed from his/her averaged wake time (± 15 mins) before the study begins. Assigned bedtime will be 9 h before wake.

Afternoon Light Only (ABL); Dim Room Light Control; Morning + Afternoon Light (MBL+ ABL); Morning Bright Light Only (MBL)

Gradually Shifted Sleep BEHAVIORAL

For all participants, their assigned baseline sleep/wake schedule will gradually shift earlier over 3 days in the laboratory to facilitate the phase advance shift of the circadian system.

Afternoon Light Only (ABL); Dim Room Light Control; Morning + Afternoon Light (MBL+ ABL); Morning Bright Light Only (MBL)

Eligibility Criteria

• Age: 18 Years - 20 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• between 18-20 years old
• lives in or near Chicago, IL

Sponsors & Collaborators

• Rush University Medical Center: lead

Study Sites (1)

Rush University Medical Center

Chicago, Illinois, 60612, United States

RECRUITING

Central Study Contacts

Stephanie J Crowley, PhD

CONTACT

(312) 563-4783; Stephanie_J_Crowley@Rush.edu

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: FACTORIAL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: February 8, 2021
• First Posted: February 15, 2021
• Study Start: August 22, 2022
• Primary Completion (Estimated): June 30, 2026
• Study Completion (Estimated): June 30, 2026
• Last Updated: June 10, 2025

Record last verified: 2025-06

Locations

US (1)