I dont advise to sleep over night, anything could Happen, but as D_D_D said, make back up files. Might break your chain, but at least you dont break your chain AND lvls.

NOTE: Is there a item thats doubles Lp?

NOTE 2: If I wanted to Beat the 1st demon wall, what lvl should I be, this is when you face it the 1ST time, in the story line... I guessing lvl 30