I have very recently (was discharged two weeks ago) spent 10 weeks in hospital - 5 weeks in the ICU (including two weeks on a ventilator and then I had a tracheostomy) and then 5 weeks in a normal ward. I had pneumonia, kidney failure, and sepsis.
My hair is usually completely grey in colour but I get it coloured regularly. I got an all over colour and highlights done two days before I went into hospital.
Now comes the weird thing. Although it is now three months since I had my hair coloured, I do not have a single grey root showing - not 1 millimetre! And my hair obviously hasn't grown at all. My body hair and my nails I've grown as expected during that time.
I've googled this phenomenon and apparently it is a thing, if you're in ICU and/or critically ill, your body can stop growing your head for a period of time. The article I found also said that when the hair starts growing again, it can grow back a different colour or texture 
Just wondering really, if anyone else has experienced this , either themselves or someone they know, and how long it took for the hair to start growing again ?