Luzindole is primarily used in scientific research as a melatonin receptor antagonist. It is employed to study the role of melatonin in various physiological processes, such as sleep regulation, circadian rhythm control, and seasonal reproduction. By blocking melatonin receptors, particularly MT1 and MT2 subtypes, luzindole helps researchers investigate the mechanisms of melatonin signaling in the brain and peripheral tissues. It is commonly used in neuropharmacological studies to examine the effects of melatonin on sleep onset and duration. Luzindole has also been utilized in studies related to mood disorders, neurodegeneration, and pain modulation, where melatonin pathways are thought to play a role. Due to its ability to cross the blood-brain barrier, it is effective in central nervous system experiments. Additionally, luzindole serves as a tool compound in evaluating the therapeutic potential of melatonin agonists and in understanding the pathophysiology of circadian rhythm sleep disorders. Its use remains restricted to laboratory and experimental settings, with no clinical applications approved in humans.