夢中(むちゅう)になる

むちゅうになる
expression
to become absorbed; to be engrossed
emotioncognition
1. to become absorbed in; to be engrossed in
To become so focused on or fascinated by something that one loses awareness of everything else.
ゲームに夢中(むちゅう)になる。
I get absorbed in games.
子(こ)どもたちは砂(すな)遊(あそ)びに夢中(むちゅう)になっていた。
The children were engrossed in playing in the sand.
読書(どくしょ)に夢中(むちゅう)になって、電車(でんしゃ)を乗(の)り過(す)ごしてしまった。
I got so absorbed in reading that I missed my train stop.

The pattern is ~に夢中(むちゅう)になる, where に marks the object of fascination. 夢中(むちゅう) can also be used as a na-adjective: 夢中(むちゅう)で走(はし)った (ran frantically). When used with で instead of に, it often conveys doing something desperately or without thinking, rather than being fascinated. The literal meaning of 夢中(むちゅう) is "in a dream," reflecting the idea of being so absorbed that reality fades away.