 Low light intensities may be associated with welfare costs to the hens as they prefer to eat in brightly lit environments and prefer brightly lit areas for active behaviour but dim (less than 10 lux) for inactive behaviour.Dimming the lights can also cause problems when the intensity is then abruptly increased temporarily to inspect the hens; this has been associated as a risk factor of increased feather pecking and the birds can become frightened resulting in panic-type ("hysteria") reactions which can increase the risk of injury.Being indoors, hens in battery cages do not see sunlight.