Changing Eye Color

I have a friend who has hazel eyes. But they seem to change color a lot. One day they seem very blue, another alomost gray, and yesterday they were very green. Aside from what he is wearing affecting which highlights get picked up in the eye color, what makes someone’s eyes change color? It seems more dramatic than that. My own eyes seem light brown some days and green on others.

I swear I remember a Cecil article about this, but I can’t seem to find it on the search engine.

Here we go

Hey pretty cool. What are the odds that both my boyfriend and I are in the 15% of people who change eye color. AND we both occaisionally have fat eyes. How interesting…

My eyes are part grey, part green, with hazel specks (more of them in the left than in the right eye). They can change within hours to nearly totally green or grey, and sometimes my left eye will go almost totally hazel, the other one no more than half.
I´ve always had this, and I think it´s pretty cool.
I´ve heard it has to do with emotions (well, hormones), but I´ve never really studied the subject… and there´s an awful lot of pages to wade through if you google it…
If I see this right, Cecil´s column only refers to slow, long-term changes?