How do we hold the continuity of our consciousness while we were sleeping?
If consciousness would disappear every night, then there wouldnt be continuity cause I would get the bad experience of death and a new created (created by the brian) consciousness would awake on the same hardware and with the same memory.
Our continuity of consciousness is broken momentarily while we sleep, it's the period of time when we don't remember anything. We're conscious in a very abstract way during REM sleep. Our stream of consciousness, with pretty much the same memories, resumes full operation the next morning.
I think you may be conflating the continuity of consciousness issue in uploading with continuity of consciousness in general. Humans, by design, have gaps in their continuity of consciousness called sleep. But the continuity is temporal rather than structural; we've evolved to "recover" from sleep with pretty much the same brain as we had before. Or one could say that sleep only evolved because it only supervenes very weakly on our cognitive coherence during the day and its' fitness benefits outweighed the penalties.
Some people worry about uploading because they believe their "continuity of consciousness" will be shattered upon instantiation in an alternative substrate; this flows from various beliefs regarding functional equivalence and brains, and is a troublesome philosophical issue. But what people are arguing about is different than the philosophical issues thrust upon us by the notion of sleep. This hypothesized "snipping" of continuity of consciousness during an upload is supposed to give the newly created "copy" moral indignation as to what happened to her; folks sometimes see uploading as "violating" them. You can feel violated by sleep too if you want, (I sort of do), but continuity of consciousness is only suspended, not snipped. The very human definition of identity always involves beings that sleep for about a third of their day. If your frame of reference is a *transhuman* definition of identity though, then I can sympathize with your indignation.