The Belsomra mechanism of action involves blocking the action of orexin, a chemical used in the sleep-wake cycle in the brain. The active ingredient in Belsomra is called suvorexant and it is classified as an orexin receptor antagonist. It was the first approved drug in this newer class of drugs used for insomnia. In clinical studies, people fell asleep faster and stayed asleep longer when using Belsomra compared to those taking placebo.