Japanese by Example
Learning through examples in manga

Becoming lightheaded with 気が遠くなる

意識(いしき)がなくなる。正気(しょうき)(うしな)う。

To lose consciousness. To lose one's sanity.

Goo Dictionary

()(とお)くなる means to become lightheaded, to feel faint, or to be overwhelmed. Your 気 (spirit) does the action of 遠くなる (to become distant) from you. It can also mean to faint or pass out.

Examples

美少女戦士セーラームーン » Volume 6 » Page 264

Further Reading

  • Garrison, Jeff et al. Kodansha's Dictionary of Basic Japanese Idioms, Kodansha, 2002, pp. 245–246