There is provided a formulation suitable for transmucosal administration comprising a short acting hypnotic drug, which formulation provides a measurable plasma concentration of drug within 10 minutes of administration. The formulation is capable of providing sleep on demand, and preferably comprises particles of drug, for example zolpidem or a pharmaceutically-acceptable salt thereof and a mucoadhesion promoting agent, such as sodium carboxymethylcellulose, which particles of drug and mucoadhesive are presented upon the surface of larger carrier particles.