I would take the existential dread a step further: am "I" even the same person I remember being yesterday?

I seem to be a conscious entity, and I have access to the physical memory store in my brain, but am "I" actually going to survive falling asleep tonight? Or am "I" like a fire that gets extinguished, with a new one to be lit in my place tomorrow morning, using the same pile of half burnt logs?

The old sci-fi/philosophy teleportation question addresses this with the concept of physically destroying and reconstructing a body, but I don't know if we need near magic tech to elicit the problem.

We turn our conscious selves off for periods of deep sleep every day (or two, or three... but there is a definite limit). Do we really survive this transition?