Light is a critical environmental regulator of biological function in poultry, significantly influence on physiology, behavior, growth, production, and reproduction. Beyond its role in vision, light acts as a potent zeitgeber that synchronize circadian rhythms, and modulate neuroendocrine signaling and metabolic pathways essential for health and welfare. This review systematically evaluates current evidence on the role of modulated light environments in poultry production systems. For this purpose, comprehensive literature search was conducted using PubMed, Web of Science, Scopus, and Google Scholar to retrieve peer-reviewed studies published between 2000 and 2025. Studies were selected based on predefined inclusion criteria focusing on light spectrum, intensity, photoperiod, and light source in relation to poultry physiology, behavior, performance, and reproduction, while studies involving non-avian models or insufficient methodological detail were excluded. Collectively, the reviewed evidence demonstrates that variations in light wavelength, intensity, and duration significantly regulate feed intake, stress physiology, immune competence, and locomotor activity, and overall flock health. Blue and green wavelengths are consistently linked with enhanced growth performance and muscle development, whereas red light preferentially stimulates reproductive activity via activation of the hypothalamic-pituitary-gonadal axis. Optimized lighting programs improve egg production, shell quality, and hatchability while reducing aggression, feather pecking, and other maladaptive behaviors. Furthermore, light modulation also influences melatonin secretion and thermal regulation, thereby strengthening resilience against environmental stress. Emerging precision-lighting technologies, particularly LED systems and dynamic photoperiod schedules, provides new opportunities to enhance productivity, animal welfare, and sustainability. However, response variability among species, genotypes, and management systems underscore the need for integrative approaches that combine photobiology with genetics, nutrition, and welfare science. This review highlight mechanistic insights, practical implications and future directions for designing precision lighting program for to achieve poultry production goals.
