Most of the drugs used to treat chronic pain facilitate inhibitory central nervous system mechanisms as their primary mechanism of action. Suvorexant, recently approved by the FDA for the treatment of insomnia characterized by difficulties with sleep onset and sleep maintenance, has a unique mechanism of action. Suvorexant is a selective antagonist for orexin receptors (OX1R and OX2R). Orexins are considered to be involved in arousal and maintenance of the waking state.