Study Finds Dim, Blue-Depleted Indoor Lighting Lowers Stress in Shelter Cats; PetPace Smart Collar Provides Key Continuous Data

BURLINGTON, Mass. — A peer-reviewed study from Michigan State University shows that modest changes in indoor lighting can significantly reduce stress in shelter cats. Published in the June issue of iScience, the research — “Light quality and time in shelter modulate behavior and cortisol in the domestic cat (Felis catus)” — evaluated behavioral and physiological responses in shelter cats under different lighting conditions and highlighted the crucial role of the PetPace smart collar for continuous, non-invasive monitoring.

The study followed 101 cats during their first five days in a shelter environment and compared three lighting setups: standard bright lights, dim lighting, and dim blue-depleted “sunset-like” lighting. Researchers measured urinary cortisol (a primary stress hormone), validated cat stress scores, inactivity, and locomotor activity. Results demonstrated that by day five, cortisol levels were notably lower in cats housed under dim, blue-depleted lighting compared with those under standard bright light. Behavioral indicators of stress, including validated stress scores and inactivity, also declined across all groups as cats acclimated to their new environment.

Continuous objective measurement was a foundation of this research. The PetPace smart collar, which is designed specifically for companion animals and clinically validated for research use, provided 24/7 AI-enabled monitoring of activity, vital signs proxies, and circadian patterns. Fitted to cats at enrollment, the collars recorded high-resolution movement intensity and daily rhythms without disturbing the animals. Data showed consistent activity peaks at “lights on” across conditions, and these circadian patterns helped researchers link lighting changes to both physiological and observable behavioral shifts.

“The PetPace collar was an essential tool in our study, providing continuous, high-resolution data that allowed us to detect clear circadian patterns and helped validate the stress-modulating effects of the lighting interventions. The collars were straightforward for undergraduate researchers to implement, enabling reliable around-the-clock data collection with minimal disruption to the cats — a result that would not have been achievable with spot-check methods,” said Dr. Alexandra Yaw, lead researcher on the project.

The study combined objective collar data with urinary cortisol assays and standardized behavioral observations, giving a robust, multi-modal view of how light quality affects shelter cats. The dim blue-depleted lighting mimicked sunset-like spectra and appeared to support more rapid physiological recovery from acute stressors associated with intake and environment change. Behaviorally, cats in all groups tended to show reduced stress signs over time as they acclimated, but the physiological marker (cortisol) provided clearer evidence of lighting-specific benefits by day five.

PetPace’s technology differs from consumer-focused pet wearables that concentrate mainly on GPS or basic fitness tracking. Built for clinical precision and continuous research-grade monitoring, the PetPace collar enabled the study team to gather objective, high-resolution data ideal for veterinary research, shelter welfare programs, and applied animal behavior science. The collars’ cloud-based analytics and continuous capture allowed early detection of subtle changes in activity and circadian rhythms, reinforcing the value of remote monitoring in real-world animal care settings.

“We’re pleased to see PetPace technology support high-impact, welfare-focused research,” said Dr. Asaf Dagan, Cofounder and Chief Veterinary Officer of PetPace. “Objective, real-time insights into stress and behavior help shelters and veterinarians make informed, ethical decisions that improve animal outcomes.”

By enabling low-burden, ethical monitoring in actual shelter environments, the PetPace collar helped translate laboratory-style measurement into practical welfare improvements. The results support adopting light-management strategies that reduce blue light exposure during critical intake periods and highlight the importance of continuous physiological and behavioral monitoring in evaluating shelter interventions.

This research adds to the evidence base for shelter design and animal welfare practices, showing that relatively simple environmental changes — when measured with precise, continuous tools — can produce measurable benefits for cats during stressful transitions. For more information about PetPace and its applications in research visit: https://petpace.com/researchers/