She's had a difficult few months following her split from Robert Pattinson.
And it seems Kristen Stewart's traumatic personal life has taken a toll on the 23-year-old actress, who has been seen with what seems to be a large bald patch on her head.
Kristen, who usually conceals her locks beneath hats and caps, was pictured in Berlin, Germany, last month displaying the dramatic hair loss on the right side of her scalp - thought to be down to stress.
In fact, the hair loss is so severe that Kristen's friends are said to be getting increasingly concerned about her fragile state of mind.
A source told Now magazine: 'Kristen's circle are so concerned about her that two of her friends have flown to Germany to see her.
'They want to take her to a de-stressing yoga retreat on the outskirts of Berlin.
'They've also begged Rob to visit her on set. They fear the stress is getting worse because she's been trying to make contact with him and he's ignoring all of her calls.'
It was reported recently that Kristen has been trying to arrange a reunion with her Twilight ex Robert, from whom she split earlier this year after their relationship failed to get past her infidelity with married film director Rupert Sanders.
But Robert is said to be unwilling to give Kristen another chance, having decided once and for all that their romance is over.
Kristen has been in Berlin shooting her new movie Sils Maria in Germany, alongside co-star Juliette Binoche.
According to reports, Kristen has been using hair extensions in a bid to conceal the hair loss while shooting the movie.
Hair expert Gary Heron from The Hair Centre in Westminster said after seeing the pictures of Kristen: 'It appears Kristen has telogen effluvium. This means the growth of hair is interrupted prematurely and the growth cycle isn't as it should be.
'Her hair is very thin and the loss looks extensive. Kristen is far too young for this not to be have caused by stress. To remedy the situation, Kristen needs to change her lifestyle.
'She should start eating a balanced diet, which will assist regrowth, and take better care of her hair.'