Historically, first barbiturates and then
benzodiazepines were indicated as sedative-hypnotics.
While both classes have demonstrated efficacy
for insomnia, barbiturates were shown to have
unacceptable levels of tolerance and dose escalation,
abuse potential, lethal dose threshold, and alterations
to SWS and/or REM sleep. Similar attributions were
made for the benzodiazepines, albeit with far less
evidence.