The invention relates to a controlled-release formulation for preventing and / or treating sleep disorders comprising Zaleplon or a pharmaceutically acceptable salt thereof in
immediate release form and
Zolpidem or a pharmaceutically acceptable salt thereof in sustained release form, wherein Zaleplon or a pharmaceutically acceptable salt thereof and
Zolpidem or a pharmaceutically acceptable salt thereof are released in two phases where the first phase is a
immediate release phase of Zaleplon or a pharmaceutically acceptable salt thereof and the second phase is a sustained release phase of
Zolpidem or a pharmaceutically acceptable salt thereof.