I think of "sunrise" as being either the general time when the sun is rising (aka dawn), and the specific moment when the sun is visible at the horizon ("sunrise will be at 6:14 AM according to the almanac"). Same for sunset and dusk.

Sundowning is an interesting word. It describes the onset of confusion or dementia associated with the fall of night. It is often seen in older patients in the hospital who are perfectly fine all day but at night become confused or agitated.