What is the impact of benzodiazepines on sleep architecture?

• A. They increase REM sleep and slow-wave sleep.
• B. They have no effect on sleep stages.
• C. They reduce REM and slow-wave sleep, fragment sleep, and can cause dependence and tolerance.
• D. They deepen slow-wave sleep without adverse effects.

Answer: (C)

Benzodiazepines alter sleep by dampening brain activity through GABA-A receptor enhancement, which changes how sleep stages occur. This leads to suppression of REM sleep and a reduction in slow-wave sleep (deep NREM sleep), so the most restorative portions of sleep are diminished. At the same time, sleep tends to become more fragmented, with more awakenings and lighter sleep overall. With longer use, tolerance develops to the sleep-inducing effects and dependence can form, so stopping them can cause rebound insomnia and REM rebound. This combination—less REM and deep sleep, plus fragmented, less restorative sleep and potential dependence—explains why these drugs have that particular impact on sleep architecture.