在美剧中祝你晚安的常用说法是 "Good night"。 你也可以说 "Sweet dreams" 或者 "Sleep well"。
例句：
"Good night, sweet dreams."
"I'm going to bed now. Good night!"
"Have a good night's sleep."
"Sleep well tonight."
你还可以用不同的语气来表达不同的含义。例如，如果你想表达温馨的祝愿，你可以说：
"I hope you have sweet dreams tonight."
"I hope you sleep well and wake up feepng refreshed."
如果你想表达强调，你可以说：
"You need to get some rest. Good night."
"It's time for bed. Good night."
你还可以用多种方式来表达祝愿，例如：
"Good night and sleep tight."
"Good night, don't let the bedbugs bite."
希望这些信息对你有帮助。