Shift Work Health Risk Calculator

No — it's a heuristic scoring model that combines the general direction and relative weight of findings from shift-work epidemiology research into a single number for comparing schedules against each other. It is not a calibrated clinical instrument or a substitute for individual medical evaluation, and shouldn't be read as a validated risk percentage.

Each night shift worked per week adds a fixed, independent amount to the composite risk score in this model, reflecting research linking night work to circadian disruption, so with every other factor held fixed, working more nights per week always increases the calculated score, up to the overall 100-point cap.

Chronobiology research generally finds the human circadian clock adjusts more easily to a schedule that delays sleep onset (day to evening to night, a "forward" rotation) than one that advances it (a "backward" rotation), because the body's natural internal clock cycle runs slightly longer than 24 hours, making delays easier to absorb than advances.

Years of shift-work exposure adds to the score as a nondecreasing function that caps once cumulative exposure reaches a threshold, reflecting the idea that health-relevant cumulative exposure eventually plateaus in this simplified model rather than growing without limit for someone who has worked shifts for decades.

Treat it as a prompt to advocate for schedule changes — favoring forward rotation, limiting consecutive night shifts, and building in adequate recovery days between shift blocks — and to discuss shift-work history with a healthcare provider during routine screening, rather than as a diagnosis of any specific health condition.