Light intensity, spectrum, photoperiod, and uniformity in laying hen housing have profound welfare effects on behaviour, stress, health, and the ability to perform natural activities throughout the laying cycle.
Lighting is one of the most powerful and underutilised welfare management tools in laying hen production. Hens perceive light fundamentally differently from humans — they see UV wavelengths, detect flicker at higher frequencies, and are more sensitive to rapid light changes. Systems designed around human perception of adequate lighting may be stressful or inadequate for hens. The welfare benefits of appropriate lighting are multiple: better social recognition reduces misidentification-driven aggression, UV access improves behaviour, appropriate dark periods support rest and immune function, and gentle transition lighting prevents panic-driven injuries. These improvements are largely achievable through low-cost lighting system upgrades and are increasingly incorporated into advanced welfare certification standards. The interaction between lighting and other welfare factors — particularly stocking density and enrichment — means lighting improvements work best as part of a comprehensive welfare programme.