Buried alive

One of my greatest fears - being buried alive. In general, I have a very good relationship with my parents. I love them, they superly love me.

I dreamt once, that one of my parents had passed away. I flung open the coffin lid at the funeral and started crying while slumped over the body. I cry and cry for ages, until I eventually fall asleep. When I wake up later on, I discover that I am in an airtight container with the body underground.

Sheer terror takes a grip on me. It's really frightening. The feeling of being trapped. It's rather ironic. I have the freedom to move, wave my arms about and leave the house, but in my sleep, I'm stuck. I can't move.

When I wake, I'm gripping onto the bedsheets. My pillow is usually wet from tears. I HATE crying in my sleep. Puffy eyes...

Why do people have nightmares? This is something I actually want to know..