[Novel insomnia drugs, including drugs currently under development].

Insomnia has mainly been treated with the hypnotic benzodiazepine (BZ). Recent studies have revealed the role and mechanisms of BZ receptors and have led to the development of non-BZ hypnotics. The chemical structures of non-BZ hypnotics differ from that of BZ; these hypnotics selectively bind to the omega 1 receptor of the gamma-aminobutyric acid (GABA)-BZ receptor complex. Because the omega 2 BZ receptors have adverse effects such as muscle relaxant actions, non-BZ hypnotics have lesser adverse effects than BZ. Antipsychotics, antidepressants, and antihistamines are also used for the treatment of insomnia in patients with other medical problems such as schizophrenia and depression. Currently, novel hypnotics are being developed with the manipulation of neurotransmitters and non-GABAergic receptors such as the melatonin and serotonin receptors.