breathing of a sleeping person; sleeping breath
Refers to the soft, steady sound or rhythm of someone's breathing while asleep. Often used in quiet, peaceful descriptions.
赤ちゃんの寝息が聞こえてきた。
I could hear the baby's sleeping breath.
彼の寝息はとても静かだ。
His breathing while asleep is very quiet.
I could hear my child's breathing from the next room.
The mother listened closely to the soft sound of her child's sleeping breath.
Maybe because of a fever, the child's breathing during sleep was irregular.