Suvorexant (Belsomra(®)), a first-in-class, orally active dual orexin-1 receptor 
and orexin-2 receptor antagonist, has been developed by Merck for the treatment 
of insomnia. Variations in the levels of the neuropeptides orexin A and orexin B 
have been linked to circadian rhythms and wakefulness. Orexin-producing neurons 
in the lateral hypothalamus regulate wakefulness by signalling through orexin 
receptors. Blockade of orexin receptors is known to promote sleep. Suvorexant 
was approved in the US in August 2014 for the treatment of adults with sleep 
onset and/or sleep maintenance insomnia. The drug is also preregistration in 
Japan, with approval submissions planned for other countries worldwide for this 
indication. This article summarizes the milestones in the development of 
suvorexant leading to this first approval for insomnia.