This book presents an overview of the role in biological processes and health effects produced by indoleamines, which are ubiquitous and versatile molecules with important physiological functions. The topics analyzed in this book cover a broad spectrum of functions played by indoleamines including the role of indoleamines in reducing free radical damage and oxidative stress; melatonin; endogenous sources and role in the regulation of fish reproduction; the neuroimmune roles of indoleamine pathways in cancer; tryptophan damage signal and indoleamine 2, 3-dioxygenase; the health effects of indoleamines on cognition, in the prevention of brain aging and age-related diseases; melatonin as an ocular anti-inflammatory; the relations between water-soluble B vitamins and indoleamines; melatonin in neurodegenerative, psychiatric and systemic inflammatory disorders; tryptophan, indolamines and sleep; from human milk to tryptophan-enriched diets; function of indoleamines in biological processes with emphasis on lipid peroxidation and indoleamines in edible plants; and the role in human health effects.