Optimal schedules of light exposure for multiple individuals for Quick Circadian Alignment

The invention of quick transportation modes that allow trans-meridian travel has caused circadian misalignment to be a common problem amongst people today. This leads to lower cognitive alertness in the short term and increases the risks of other maladies in the long term. Light, when applied at correct levels and times, can shift and re-entrain the circadian clock to the local time zone, and minimize the negative impact of any circadian misalignment. In this paper, we developed a new method (algorithm) to calculate common optimal light schedules of light exposure and avoidance, to quickly re-entrain the circadian systems of a group of individuals who have different internal circadian parameters. We used an experimentally validated mathematical model to define a target circadian phase, from which, our optimization algorithm iteratively adjusts the switching times of a bang-bang light input (restricted to two light levels) to minimize the difference between the current phase of all individuals and the target phase, within a set time period. The proposed algorithm generated light schedules that successfully minimizes the re-entrainment time of all the individuals with phase shifts up to 12 hours of delay or advancement.