Temazepam is a minor metabolite of diazepam (valium). It has no notable active metabolites of its own. Like other benzodiazepines, it acts on the gamma-aminobutyric acid (GABA) receptors in the brain, enhancing their neurotransmissions. GABA acts as a ‘nerve calming’ agent that reduces anxiety and relaxes the muscles, hence the popularity of temazepam to aid sleep.
Temazepam is relatively long acting (6-24 hours), metabolises well, and can lead to a quick build-up of tolerance and addiction. As a result, when prescribed to combat insomnia, it is only used for short periods of time (1-2 weeks on average) and at the lowest functional dose for the patient (from 5mg upwards).