With things on my mind, it's hard to sleep peacefully.
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Literary equivalent of 安睡 (ānshuì) — 寝 is the classical word for 'sleep/lie down,' compare 寝室 (qǐnshì, dormitory). Use in formal writing, condolences (e.g. 安寝于地下), or polite goodnight wishes; in conversation say 睡个好觉 or 晚安 instead.