To say good night in Portuguese, Brazilians say “boa noite”. If you are interested in expanding your Portuguese vocabulary, there are a few other things that you can say when telling someone good night in Portuguese:
Dorme com Deus – Sleep with God (Brazilians have a tendency to mention God in common phrases, you will notice this especially when saying goodbye in Portuguese)
Sonhe/durma com os anjos – Dream with the angels (“sonhar” means to dream in Brazilian Portuguese)
Dorme bem – Sleep well (“dormir” is the verb for to sleep in Brazilian Portuguese)
Tenha uma ótima noite! – Have a great night!