At night, the pupils dilate to allow in more light.

晚上，瞳孔放大以便让更多的光线射入。

《柯林斯英汉双解大词典》

Pupils dilate, palms become sweaty and the heart rate increases.

瞳孔放大，手心出汗。心率加快。

youdao

Your pupils dilate, your blood pressure rises, as a response your livers dumps more sugar into your bloodstream.

你的瞳孔变大，血压上升，进而你的肝脏运输了更多的糖分到血液中。

youdao

If, in addition, you see his eyes open wider and his pupils dilate, you know for certain that he has a much greater interest in this particular option.

FORBES: Body Language Savvy for Sales