A reader (Dozy) asks, Does Ambien affect sleep architecture? If so, how?
Ambien is a benzodiazepine agonist that binds to the alpha 1 subtype of the GABA-A receptor. It is therefore more selective then the benzodiazepines such as valium, ativan, and xanax.
The benzos (valium, etc) tend to increase stage 2 sleep while decreasing deep sleep (stage 3 and 4 ) and decreasing REM sleep. These effects are mild.
Ambien has minimal effects on sleep architecture. In many studies, its effect on sleep stages is no different than placebo. In at least one study, it increased deep (slow wave) sleep.
The brief answer to your question is that, in short-term studies, Ambien decreases sleep latency (time to fall asleep) and increases total sleep time with no significant effect on sleep architecture.