Welcome to the site....
Its normal for most anemones to sometimes close up, many will do that when feeding or at night, ect...rarely is that any indication that one is sick....Many anemones are also brown...
It might help if you could tell us the species of anemone that your refering to and give more details and history about your system.
Also, there is a seperate section on the site for anemone discussions that might get more responces if you ask there...