She stood up too fast and felt a moment of dizziness.
Tips
usage
眩 is literary and usually appears in compounds: 眩晕 (vertigo), 目眩 (dazzled/dizzy), 头晕目眩 (dizzy and seeing stars). On its own, it can also mean 'to dazzle' as a variant of 炫.
目 on the left is the eye radical, a vertical pictograph of an eye stood on end. It tags 眩 as something that happens to vision, alongside 眠 (sleep), 睛 (pupil), and 盲 (blind).
玄 supplies the reading, shifting tone from xuán to xuàn. Its sense of dark and unfathomable adds a flavor: dizziness is when the eyes go murky and the world swims, the visual world turning xuán-deep.