I have never experienced this, or met anyone who has. I once almost experienced it through someone else's eyes while spirit-wandering, but got out before we actually hit the ground...*blood running cold*
My first instinct was to ask what they saw...*d'oh*
However, on serious note, I feel that Zorya's reply is good...*well done Zorya!*...I think it might have something to do either with an actual fear of death, or , metaphorically, an unwillingness to sacrifice in order to grow. Is your friend coming up to any hard decisions? *straining for an example*..like...giving up a job to pursue a dream career/college course,
...a feeling of insurmountable issues, coupled with a knowledge that you can still actually change the situation if you give up time from other things you love doing.
Oh!...and i think its a basic stage of growing up to realise your mortality at some point...at least, I know I did, and several of my friends did...dreaming death could be a manifestation of this if it is blocked conciously...