Lighting regimes in broiler houses affect sleep, activity, circadian rhythms, and overall welfare. Evidence-based lighting standards are a key component of higher-welfare production.
Lighting is a powerful environmental variable in broiler welfare that is often underemphasised relative to stocking density and breed. Continuous or near-continuous lighting — motivated by the belief that feed intake and growth are maximised when birds are active — compromises sleep and circadian function, contributing to immune problems and welfare deficits. Adequate dark periods enable sleep that is essential for immune function and cognitive health. The light quality, intensity, and spectral composition all affect bird behaviour and welfare. Higher-welfare standards specify not just duration but also intensity and transition management to mimic natural light conditions more closely.