Abstract
Light exposure plays a critical role in regulating physiological and behavioral processes. This study aimed to explore how different light spectra influence locomotor activity, anxiety-like behavior, and heart rate variability in rodents. We used spontaneously hypertensive rats (SHRs), which exhibit distinct behavioral traits compared to normotensive Wistar-Kyoto (WKY) rats, as a model to examine strain-related differences in response to light conditions. Given known sex differences in behavioral phenotypes and light sensitivity, and the higher prevalence of certain behavioral traits in males, this study focused on male rats. Animals were exposed to white, blue, green, or red light-emitting diodes (LEDs), and their behavioral and physiological responses were assessed through locomotion tracking and electrocardiography. The results showed that both light spectrum and intensity significantly influenced activity levels, anxiety-like behavior, and heart rate in a strain-dependent manner. These findings provide insights into how spectral qualities of light affect behavior and physiology, and suggest potential considerations for light environment design in future behavioral and translational studies. SIGNIFICANT STATEMENTS: Blue light consistently suppressed motor activity and increased anxiety-like behavior in SHRs, who also showed greater heart rate elevations and heightened autonomic sensitivity to light compared to WKY rats.