What does “bedroom eyes” mean, from a physical standpoint, if anything?

Question

The phrase "bedroom eyes" came up in another question, and the person who used it remarked that to him/her it meant that, from a physical standpoint "that means they've got dilated pupils".

This didn't mesh with what I remembered hearing, which was that the eyes were semi-lidded.

Dictionary.com mentions nothing about either. UrbanDictionary, for whatever that's worth, mentions semi-lidded eyes a couple times, but not as the highest rated answers.

Is there any specific physical implication to having "bedroom eyes"?

Answer 1

Dilated pupils or heavy lids are not essential to the meaning of the expression. No specific physical aspect is implied. Any “way of looking at someone that shows you are sexually attracted to them” (Macmillan Dictionary) can be called bedroom eyes.

But it would certainly not be wrong to refer to dilated pupils as bedroom eyes. One cause of dilated pupils is sexual arousal. See Wikipedia’s article on the subject, “Mydriasis”, under the subsection titled “Effects”. Furthermore, in scientific studies, subjects rate images of people with dilated pupils as more attractive, and a tea made from the poisonous plant Atropa belladonna has been used by countless women to dilate their pupils or “darken the eyes”; hence the name of the plant, bella donna, Italian for “beautiful woman”.

(Image from the article “Eye Signals”, published in Westside Toastmasters, For Public Speaking and Leadership Education.)