The Hairspray star was detained on an involuntary 5150 psychiatric hold on Monday (22Jul13) amid fears for her mental health after she was caught attempting to set fire to a driveway in Thousand Oaks, California.
Benson sparked controversy two days later on Wednesday (24Jul13) when she posted a picture of herself imitating Bynes on her Instagram.com page with the caption, "Doing my Amanda Bynes look this afternoon".
The post prompted a negative backlash and she has now apologised. In a series of posts on Twitter.com, Benson writes, "To clear up the whole Instagram thing, I had no idea what her situation was. Truly sorry if I offended anyone... Love you guys."
Bynes' parents have applied for a conservatorship to take control of their daughter's affairs and a judge has extended her detention for a further two weeks.