Poultry Lighting: Duration, Intensity, and Laying Hen Welfare

Lighting programmes in poultry houses profoundly affect laying hen welfare, influencing circadian rhythms, stress levels, fearfulness, and the incidence of aggressive behaviours.

Key Facts

Hens require a minimum 8-hour dark period to maintain normal circadian rhythms and immune function
Constant or near-constant lighting, once common, increases fearfulness, mortality, and productivity loss
Very low light intensity (below 5 lux) reduces aggression but impairs activity and natural behaviour
Natural or simulated dawn/dusk transitions reduce stress responses and improve flock welfare
UV light provision allows hens to see the full visual spectrum they evolved with, improving foraging

Welfare Considerations

Poultry lighting is a welfare lever that is well-understood in research but inconsistently applied in practice. Chronic disruption of circadian rhythms through artificial light manipulation causes immunosuppression, increases stress hormones, and accelerates physiological ageing. Hens evolved for natural light cycles and respond adversely to the extremes imposed by intensive production. Minimum dark periods of 8 hours, gradual light transitions, and species-appropriate lux levels are achievable at low cost and should be standard. UV provision allows hens to perceive their environment as nature intended, enabling better foraging decisions and reducing anxiety. Welfare certification should specify minimum dark periods and maximum continuous light hours.

What You Can Do

Support laying hen certification schemes that specify lighting requirements including dark periods
Choose eggs from farms with transparent welfare claims about lighting management
Advocate for mandatory lighting standards based on welfare science, not production optimisation