# Influence of photic perturbations on circadian rhythms

## TL;DR

This paper investigates how continuous light perturbations affect the circadian clock's dynamics using a minimal nonlinear model, revealing 12-hour harmonic responses and the role of trajectory irreversibility.

## Contribution

It introduces a stochastic modeling approach to analyze the impact of photic perturbations on circadian rhythms, emphasizing trajectory irreversibility and harmonic responses.

## Key findings

- Identification of 12-hour harmonic oscillations.
- Modeling of photic perturbations as stochastic processes.
- Highlighting the importance of trajectory irreversibility.

## Abstract

The circadian clock is the molecular mechanism responsible for the adaptation to daily rhythms in living organisms. Oscillations and fluctuations in environmental conditions regulate the circadian clock through signaling pathways. We study the response to continuous photic perturbations in a minimal molecular network model of the circadian clock, composed of 5 nonlinear delay differential equations with multiple feedbacks. We model the perturbation as a stationary stochastic process, and we consider the resulting irreversibility of trajectories as a key effect of the interaction. In particular we adopt a measure of mutual mapping irreversibility in the time series thermodynamics framework, and we find 12 hours harmonics.