You also sleep best when you are comfortable. Tight clothes and heavy covers interfere with good rest. Poor ventilation disturbs sleep.

你感到舒服的情况下，睡得最香。衣服过紧，盖得太厚都影响休息。通风不良干扰睡眠。

youdao

And,if you wish someone good night, you might say, "sleep tight -- don't let the bed bugs bite."

VOA: special.2009.06.28

Sleep tight Rosie Mc x.

BBC: Coleen Rooney's sister Rosie dies

I'm the single mother who has been trying to teach her child to sleep in their own bed, who holds them tight long into the night, thanking God it wasn't her child that died.

BBC: What's your favourite poem?