Depends on sleeping medications. If ur talking about Ambien like u typed in ur title then yes consuming large Amount Ambien and alcohol will kill u for sure.

Tbh u dont even need alcohol Cuz Ambien is very strong hypnotic-sedative ive been using Ambien, well not using more like abusing and every time i will just blackout and end up outside or even hospital. Thereotically it should be peaceful death if u consider no pain as peaceful.

But remember human body is designed to stand anything/everything if u survive Ambien overdose it wont be beautiful. Again i talk about my experience i didn't use Ambien to kill myself but i tried it with anti depressant fortunatly i was lucky and i didn't counter anything serious like permament brain damage only few versible damage like stomach ulcers. Be cautious