off one's head

形容詞

Insane, crazy. / Temporarily mentally unstable; very distressed. / Under the influence of drugs.

日本語の意味

正気ではない、狂っている状態 / 一時的に精神状態が不安定な状態 / 薬物の影響下にある状態

When sleep-deprived, one can feel completely off one's head.

睡眠不足になると、まったく正気でなくなることがある。

意味（1）

Insane, crazy.

意味（2）

Temporarily mentally unstable; very distressed.

When I had finished I went and saw poor Leo, who was quite off his head, and did not even know me.

意味（3）

Under the influence of drugs.