Tasimelteon

The role of the melatonin in relation with circadian rhythms and the sleep/wake cycle is well established. It is thought to play a role in controlling the sleep–wake cycle through physiological processes regulated in the suprachiasmatic nucleus of the hypothalamus. In normal subjects, the endogenous circadian period is a little over 24 h, but is entrained to the 24-h day through exposure to light. In the absence of light or light perception (totally blind), the synchronization is lost and the circadian rhythm follows the intrinsic non-24 h clock, resulting in a non-24 h sleep–wake disorder. Non-24 h sleep–wake disorder is characterized by a misalignment of the 24-h light/dark (LD) cycle and a non-entrained sleep/wake cycle propensity resulting in asymptomatic periods alternating with episodes of insomnia, excessive daytime sleepiness (EDS), or a combination of both. Tasimelteon (VEC-162) is an orally bioavailable melatonin receptor agonist of the melatonin MT1 and MT2 receptors recently approved by the U.S. Food and Drug Administration (FDA) for the treatment of non-24 h sleep–wake rhythm disorder.