Good night!
'Buonanotte' — BUO-na-NOT-te. Four syllables — can be said as one word (standard) or two ('buona notte'). Stress on the first and third syllables.
Use when parting for the night — at the end of an evening visit, before sleeping, or when someone is going to bed. Works in all registers.
'Buonanotte' (good night) is one word in Italian, unlike 'buona sera' (good evening) which is two. It's said as both a goodbye (I'm leaving) and a sleep wish (going to bed). Context makes the meaning clear. It's one of the most universally warm Italian phrases.
Fai sogni d'oro!
Sweet dreams! (lit. Have golden dreams!)
'Sogni d'oro' (golden dreams) — the Italian equivalent of 'sweet dreams'. Very tender.
A domani, buonanotte.
Until tomorrow, good night.
Combines the 'until tomorrow' promise with the good night wish — warm daily routine
Dormi bene!
Sleep well!
Simple imperative — wishes good sleep. Less formal than 'fai sogni d'oro'.
Italian dinner hosts insist on walking guests to the door (and sometimes to their car) at the end of an evening. The goodbye conversation at the doorstep can last 20-30 minutes — leaving an Italian home involves a lengthy farewell ritual that neither party seems to want to end.