Which statement best describes sleep onset latency and its pharmacologic modulation by benzodiazepines?

• A. It measures total sleep time and is increased by benzodiazepines
• B. It is the time to fall asleep and is decreased by benzodiazepines
• C. It measures REM duration and is unaffected by benzodiazepines
• D. It is the time awake after sleep onset and is increased by benzodiazepines

Answer: (B)

Sleep onset latency is the interval from trying to fall asleep to actually falling asleep. Benzodiazepines, by enhancing GABA activity, produce sedation and faster sleep onset, so they decrease this latency. The other statements mix up what sleep onset latency measures (total sleep time, REM duration, or wake time after sleep begins) and don’t describe the specific change benzodiazepines produce on the time it takes to fall asleep. In short, it’s the time to fall asleep, and benzodiazepines shorten that time.