sleeping posture; sleeping position
Refers to the way a person's body is positioned while sleeping, often used when describing restless sleepers or habits.
彼は寝相が悪くて、よく布団から落ちる。
He has bad sleeping posture and often falls out of the futon.
I adjusted the baby's sleeping position.
It's hard to correct a child's sleeping posture.
寝相 refers to one's sleeping posture or how one moves in sleep, while 寝冷え refers to falling ill from being chilled while asleep, so the two are easily mixed up because both start with 寝.