[New hypnotics: perspectives from sleep physiology]

Insomnia is a disorder that affects a large part of the population. Agents that are used to treat this sleep disorder have evolved: benzodiazepines replaced barbiturates, but there is still concern about their residual effects and about the development of dependence and the risk of withdrawal symptoms. Currently the benzodiazepines receptor agonists (zolpidem, zaleplon, zopiclone and eszopiclone) are the agents most widely prescribed. Pharmaceutical technology and the advances in the knowledge of sleep physiology have led to the availability of some novelties like modified release zolpidem (indicated not only to initiate but also to maintain sleep., ramelteon and agomelatine (melatonine receptors agonists). This article summarises these subjects as well as the pharmacology of investigational drugs, such as indiplon (another benzodiazepine receptor agonist), gaboxadol ( a selective extrasynaptic GABAA agonist -SEGA-), and some anticonvulsant drugs that could be useful as hypnotics: tiagabine ( a GABA transporter inhibitor), pregabaline and gabapentine (GABA analogs). The possible usefulness of 5-HT2A/2C antagonists is also addressed.