expression, godan verb (-ru)
sleep in peace; sleep without fear
Idiomatic expression meaning to sleep soundly without worry or anxiety, often used when a source of concern has been removed.
See also: 枕を高くして寝る
試験が終わって、やっと枕を高くして眠れる。
Now that the exams are over, I can finally sleep in peace.
犯人が捕まったから、今夜は枕を高くして眠れそうだ。
Since the culprit was caught, I think I can sleep without fear tonight.