Almorexant HCl is primarily investigated for its potential in treating insomnia and other sleep disorders. It functions by selectively blocking orexin receptors in the brain, which play a key role in regulating wakefulness. By inhibiting these receptors, Almorexant HCl promotes the transition to sleep and helps maintain sleep continuity without affecting the natural sleep architecture significantly. It has shown promise in clinical trials for improving sleep onset and duration, particularly in patients with difficulty maintaining sleep. Unlike traditional sedative-hypnotics, it does not act on GABA receptors, potentially reducing the risk of dependency and next-day residual effects. However, development was discontinued due to safety and liver toxicity concerns, despite favorable efficacy in sleep promotion.