also: ねちがい
noun
kink in the neck; sprained neck
Refers to a stiff or painful neck caused by sleeping in an awkward position.
See also: 寝違い
朝起きたら寝違えで首が痛かった。
When I woke up this morning, my neck hurt from sleeping wrong.
寝違えがひどくて、首を回せ
My neck is so stiff from sleeping wrong that I can't turn it.
Verb form meaning 'to sleep in an awkward position and hurt one's neck'; 寝違え is the noun form describing the resulting condition.
Compound of 寝 (ne, 'sleep') and 違え (chigae, 'difference' or 'mistake'), literally 'sleep mistake'.