The FDA has approved zaleplon (Sonata, Wyeth-Ayerst Laboratories, Philadelphia), a very-short-acting hypnotic agent that reduces time required to fall asleep, for the treatment of insomnia. Zaleplon is a nonbenzodiazepine hypnotic of the pyrazolopyrimidine class that interacts with the GABA-BZ receptor complex although it is unrelated to benzodiazepines, barbiturates, or other drugs with known hypnotic properties.
Zaleplon has a very short duration of action—its half-life is 1 hour. Clinical trials of the drug involving 3562 patients with chronic and transient insomnia demonstrated a consistent reduction in the amount of time required to fall asleep, without any increase in the total amount of time slept or a significant decrease in the total number of waking times during the night. Because of its short duration of action, patients generally had no residual drowsiness after only 4 hours of sleep. The drug did not demonstrate effectiveness in treating difficulty with shortened total sleep time or increased awakening during the night.
Henney JE. New Drug for Sleeplessness. JAMA. 1999;282(13):1218. doi:10.1001/jama.282.13.1218-JFD90008-2-1