Most sleeping pills are made up of chemical compounds that are ligands for allosteric modulatory binding sites on the GABA(A) receptor. Polysomnographic studies demonstrate that these hypnotics effectively increase the ability to fall and to stay asleep, but disrupt the physiological sleep profile (typical electroencephalograms (EEG) for the awake state and the different states of sleep are shown). Hence, there is an urgent need for sleep-promoting substances with a different mechanism of action. GABA analogues are one class of promising molecules.