In terms of terrifying in terms of what I've actually seen rather than experienced...

Some old fragile lady that looked over a century old kept rolling herself out of bed in attempts to kill herself. Her bones were jolting out from her paper thin skin and covered in all these dark bruises. I would hear the thuds then her screaming blue murder at any nurses who assisted her. Each thud I would wince would be the one.

There was a woman behind a curtain in A and E that had come to harm of herself being issued with paperwork by a social worker that her mental health problems meant that they were taking her children away because she had no relatives - I heard that poor womans blood curdling screams. The way the social worker delivered it to her nonchantedly and the sobbing that left that womans mouth have actually given me trauma. I never saw her face but I just wanted to give that woman a cuddle.