That seems likely.

An obvious thing perhaps worth mentioning: if you're shortsighted (or longsighted) then you see better in bright sunlight because the iris closes, giving you greater depth of field, so that might make people think/feel that sunlight "cures" myopia.

(On the other hand, if you have excellent eyesight then you see better in less bright conditions because your vision is being limited by diffraction at the aperture.)