Existential angst.

That took me back - I did A level French and suffered greatly from years of having to read Jean-Paul Sartre's novels. I think he practically invented the angst part, let alone the existentialist movement.

www.iep.utm.edu/sartre-ex/

Reading this sort of stuff is bad enough in English, doing it in French was the best soporific ever.

In that case I've got it. Thank you for explaining

Not knowing whether your life has any meaning or purpose and struggling to accept that's all there is - and then you die.

I guess the trick is to find a way to come to terms with one's mortality and get the best out of life whilst we're here.