There wasn't any noticeable side effects of the Loss ending. As far as how the regains happened as gradual versus instantaneous, I left that to player discretion so it could be either as you like! The effects were set to end on a specific day (except for long term Loss people) so it could have taken the entire day (so for blinded people, they could have regained better and better sight as the day went on, etc) or it could have happened in a split second (like someone speaking mid-sentence and WHAM memories are back, etc).