HTR2A and insomnia: The distribution of serotonin 5HT2A receptors in the brain regions known to be important in the regulation of sleep and wake, such as the hypothalamus and thalamus, aligns with the growing body of preclinical and clinical data to support a role for 5HT2A antagonists in promotion of deep sleep, and therefore these antagonists offer potential to address several unmet needs in insomnia pharmacotherapy (Vanover and Davis 2010; Zisapel 2012).