There is provided a composition suitable for oral transmucosal administration (sublingual) comprising dexmedetomidine. The composition is useful for the treatment of sleep disorders such as insomnia and capable of providing sleep on demand. The composition comprises an effective amount of dexmedetomidine or pharmaceutically acceptable salts thereof, solvates thereof, or derivatives thereof, formulated for delivery of dexmedetomidine across a subject's oral mucosa.
