[New hypnotics ramelteon for the treatment of insomniacs with circadian rhythm disturbance].

Ramelteon is a new class of sleep agent that selectively binds to the melatonin type 1 (MT1) and type 2 (MT2) receptors in the suprachiasmatic nucleus (SCN), instead of binding to GABA-A receptors such as with traditional hypnotics benzodiazepines. Ramelteon exhibits not only acute sleep-promoting effect but also circadian phase-shifting effect via MT1 and MT2 receptors respectively, and has been revealed to contribute to the treatment of acute and chronic insomnia in patients with circadian rhythm sleep disorders(sleep-wake rhythm disorders) or with inappropriate timing of sleep habits. Optimal administration plan for insomniac patients to induce these characteristic sleep-modulating effects by ramelteon was discussed.