NCT05276739

Role of Photic and Non-photic Time Cues in Resetting Circadian Rhythms

Determining the Role of Photic and Non-photic Time Cues in Resetting Circadian Rhythms in Humans

• Status: Unknown
• Phase: N/A
• Study type: Interventional
• Enrollment: 48 (estimated)
• Sponsor: Brigham and Women's Hospital · Academic / Other
• Sex: All
• Age: 18 Years – 30 Years
• Healthy volunteers: Accepted

Summary

The aim of this study is to determine the principal time cue (light or meals) for resetting circadian rhythms in melatonin and metabolic outcomes.

Detailed description

The objective of this proposal is to construct and compare PRCs describing the relationship between the timing of light exposure and meals across the 24-hour day and the size and direction of shift in circadian rhythms of circulating lipids and melatonin in humans. Completion of the work will provide mechanistic insight on the role of photic and non-photic cues mediating entrainment of circadian rhythms in humans besides that of melatonin. In this proposal, we will use the same experimental paradigm that we have successfully used previously to characterize and compare PRCs for shifts in melatonin in response to light exposure of different durations and spectra, and as used in our pilot trials demonstrating a robust PRC of lipid circadian rhythms in response to combined photic and non-photic stimuli across the day. We will achieve our objective using a randomized controlled trial in young healthy adults (n=48, 18-30 years) that systematically manipulates the timing of 6.5-hour bright light exposure and 6.5-hour time restricted eating across the 24-hour circadian cycle to specifically: Aim 1: Determine if light is the primary time cue for resetting melatonin but not lipid circadian rhythms. Hypothesis: The resetting response of circadian rhythms in melatonin but not cholesterol and triglycerides is dependent upon the circadian phase at which a 6.5-hour bright light exposure occurs. Aim 2: Determine if meal timing is the primary time cue for resetting lipid but not melatonin circadian rhythms. Hypothesis: The resetting response of circadian rhythms in cholesterol and triglycerides but not melatonin is dependent upon the circadian phase at which a 6.5-hour time restricted eating occurs. Aim 3 (Exploratory): Evaluate the acute effects of eating across the 24-hour day on circulating lipid levels. Hypothesis: The acute effects of 6.5-hour time restricted eating on circulating cholesterol and triglycerides levels are dependent on the circadian phase at which meals are eaten.

Conditions

• Light Exposure
• Meal Timing

Interventions

Type	Name	Description
BEHAVIORAL	Bright Light	6.5-hour 10,000 lux light pulse (4100K fluorescent light) centered within the 16-hour wake episode (start 4.75 hour after wake and end 11.25 hour after wake).
BEHAVIORAL	Time-restricted eating	6.5-hour restricted meal window (4 meals at 4.75, 6.9, 9.1, 11.25 hours after waking) centered within the 16-hour wake episode.
BEHAVIORAL	Dim light	dim light (\<3 lux) throughout the 16-hour wake episode
BEHAVIORAL	12-h meal window	12-hour restricted meal window (4 meals at 2, 6, 10, and 14 hours after waking) centered within the 16-hour wake episode.

Timeline

• Start date: 2022-07-29
• Primary completion: 2025-03-30
• Completion: 2025-09-30
• First posted: 2022-03-11
• Last updated: 2023-06-07

Locations

1 site across 1 country: United States