Quantifying light-dependent circadian disruption in humans and animal models

Area of Science:

• Chronobiology
• Animal Behavior
• Human Physiology

Background:

• Circadian disruption is recognized, but methods to quantify its extent in field or lab settings are lacking.
• Circadian rhythms, essential for physiological and behavioral processes, synchronize to environmental cues like the light-dark cycle.
• Phasor analysis offers a technique to quantify the synchronization of circadian rhythms.

Purpose of the Study:

• To develop and apply methods for quantifying circadian disruption and entrainment in organisms.
• To assess the utility of phasor analysis in measuring light-dependent circadian disruption across species.
• To establish a link between ecological studies of circadian entrainment and laboratory research on circadian disruption.

Main Methods:

• Utilized phasor analysis to quantify circadian rhythm synchronization to light-dark cycles.
• Developed species-specific light measurement and delivery technologies based on phototransduction mechanisms.
• Applied these methods to nocturnal rodents and diurnal humans subjected to light-dark shift schedules.

Main Results:

• Phasor analysis successfully quantified circadian disruption in both rodents and humans.
• Both species exhibited similar, monotonically increasing levels of light-dependent circadian disruption with increased light-dark shifts.
• Circadian disruption levels were quantitatively similar between rodents and humans under comparable shift conditions.

Conclusions:

• Phasor analysis provides a robust method for quantifying circadian disruption in diverse settings.
• This technique bridges ecological and laboratory studies, enabling comparative research on circadian entrainment.
• Rodents and humans display comparable light-dependent circadian disruption patterns, highlighting conserved responses to environmental changes.