Lighting programs in broiler houses affect sleep, activity, and welfare. Providing adequate dark periods for rest is a fundamental welfare requirement for farmed chickens.
Broiler chickens have been managed for decades under continuous or near-continuous lighting to maximize the time available for eating and growing. Research consistently shows the welfare cost of this approach: birds deprived of adequate dark periods develop leg problems, show immune compromise, and have measurably worse welfare outcomes than those given appropriate rest periods. The welfare of an animal bred to grow at an extraordinary rate depends partly on adequate rest for physiological recovery. Simple changes to lighting programs have meaningful, measurable welfare benefits.