According to Fred's manager this extended stay in the ICU is precautionary;

“The impact was quite strong but fortunately, it was nothing. He was conscious and able to speak.
“He was taken to hospital as a precaution and they have done all the necessary tests, which have all come out well.
“But he will need to spend another 24 hours under observation. The tests will be repeated on Monday.”
I was kept overnight for observation when I was concussed, and look how normal I am