There’s a hypothesis being tested using red lights at Parkview Dairy in Delhi, California. The new dry cow barn was constructed with red lights to better understand how light exposure regulates circadian rhythms. The concept emerged from a broader awareness of circadian biology and a recognition that traditional barn lighting often overlooks how cows perceive light at night.
Source: Bovine Veterinarian, January 27, 2026. Link. The red light is not meant to stimulate cows or increase production but as a way to avoid unnecessary circadian disruption during a critical recovery window.