What is the effect of benzodiazepines on sleep architecture?

• A. They increase REM sleep only
• B. They increase slow-wave sleep only
• C. They have no effect on sleep stages
• D. They reduce sleep onset latency, increase stage 2 sleep, and decrease REM and slow-wave sleep

Answer: (D)

Benzodiazepines promote sleep by enhancing GABA-A receptor activity, which dampens brain arousal. This shifts sleep toward lighter stages: they reliably shorten the time it takes to fall asleep and increase the duration of stage 2 sleep. At the same time, they suppress the deeper restorative stages—slow-wave sleep (N3) and REM sleep—so total REM time and slow-wave sleep decrease. The net effect is faster sleep onset and more stage 2 sleep, with reductions in REM and deep sleep. Clinically, this means easier sleep initiation but potentially less restorative sleep and possible next-day impairment or dependence with use.