> you experience discontinuity every night when you sleep

Something dubious about this. No one thinks they're annhiliated upon sleeping, then reconstituted upon waking.

Even adhering to materialism, the problem with mind uploads is the same problem as with teleportation: a copy is being made. Destroying the original does not mean a consciousness transfer then magically occurs from the original to the target. For mind uploads, the only plausible sounding way around this is the Moravec transfer, but even that is reliant on the Ship of Theseus thought experiment having a definite answer.