Light quality and time in shelter modulate behavior and cortisol in the domestic cat (Felis catus)

Light is a principal synchronizer of behavior, circadian rhythms, and hormone release patterns, including stress responses. High stress in domestic cats (Felis catus) increases risk of disease, promotes undesirable behaviors, and is associated with reduced adoptions from shelters. To determine how light properties impact stress and behavioral activity patterns in cats, the effects of light intensity and composition were tested in 101 male and female cats using standard, dim, and dim, blue-depleted light during the initial five days in a shelter environment. Cats exhibited circadian locomotor activity, peaking at lights on, in all light conditions. Cortisol levels decreased under dim, blue-depleted light versus standard light on day 5. Probability of hiding was only increased in the dim light condition. A behavioral approach test showed declined behavioral stress markers over time in the shelter. Here, we demonstrate that indoor light conditions and length of time in shelter modulate stress in cats.