Peeing and pooping outside the litter box but only at night

My baby Harley has just begun avoiding her kitty box but only at night. She is three years old and has no signs of medical issues.

This is day two of waking up to discover she has not used her kitty box. I am open to suggestions to help my baby get back on track.

I love her so much and just want to help her. Please help me figure this out.

My thoughts: If she goes during the day, but not at night, I would wonder if perhaps she's having trouble with her night vision.

If nothing has changed in her life, and the vet has said she's healthy, I'd revisit the health question.

The first thing I'd do, though, is place a night light near the litter box, and make sure that at night, she's got plenty of light to see by.

If nothing changes, I'd be curious to know if there are stray cats or perhaps wildlife visiting the property at night. This can sometimes disturb a cat enough to throw them off their box habits.

The next thing I'd look at is her routine... when she's fed, when you're playing with her, whether or not she's too active at night and not getting enough attention during this time.

I hope that helps and please let us know how she comes along.
-Kurt