Studies examining GABA(B) receptor agonists have reported effects on sleep including decreased sleep onset latency (SOL), increased sleep consolidation and increases in slow wave sleep (SWS). γ-hydroxybutyrate (GHB) is proposed to act as a GABA(B) receptor agonist; however, the mechanism of action of GHB is controversial. In addition, the GABA(B) receptor agonist, baclofen, has also been proposed to exert similar effects on sleep. The aim of this paper is to provide a review of the human clinical studies of sodium oxybate and baclofen regarding sleep and the treatment of sleep disorders including narcolepsy and insomnia, as well as other disorders involving disrupted sleep such as fibromyalgia.