Polysomnography in drug development is used to detect desirable and un
desirable effects of drugs on normal and disturbed sleep. Although thi
s method is essential for the approval of neu hypnotic drugs, it is qu
ite often neglected in the development of drugs that show unwanted sid
e effects on normal sleep. In this review, the requirements for qualif
ied polysomnography are described, the strong and weak points of the m
ethod are discussed, and its importance for the drug development proce
ss is pointed out.