Lighting programs in broiler production significantly affect bird welfare, with evidence supporting provision of adequate dark periods for rest and natural circadian rhythm maintenance.
Broilers kept under near-continuous artificial lighting are unable to rest adequately, disrupting normal physiology and behavior. Sleep deprivation causes stress and is associated with increased fear, reduced immune function, and cardiovascular pathology. The motivation to provide continuous light is economic - maximizing eating time and growth rate - at direct cost to bird welfare. Providing a minimum of 6-8 hours of genuine darkness meets basic physiological needs without catastrophic production impacts. This is one of the simplest welfare improvements available to broiler producers and is required by higher welfare standards.