That's how I feel when my alarm goes off at 6am
I have a similar sensation when jarringly awoken in the early morning, except its not that I think I'm dead, but more like there's a separation between my consciousness and my personality. Meaning I wake up and I know I'm awake, but I don't remember who I am, where I am and what I am doing. The feeling only lasts a second then my personality reloads and I remember things. I'm sure most people experience this, I just kind of find it fascinating.