Light management in poultry production has profound welfare implications through its effects on behavior, physiology, and sleep.
Poultry lighting management is a welfare domain where economic incentives directly conflict with basic physiological needs. Extended light periods increase feed intake and growth but deprive chickens of sleep that is as fundamental to welfare as food and water. Sleep deprivation in chickens causes similar physiological stress responses as in other vertebrates including immune suppression, elevated cortisol, and behavioral abnormalities. The shift to minimum 6-8 hour dark periods in progressive welfare schemes represents a meaningful welfare improvement with minimal production impact in practice. Providing appropriate spectrum lighting and managing light programs for circadian health should be standard welfare requirements rather than optional features.