I've heard there's no issue, but ease over slowly like an hour at a time. If u want to be more drastic, err on the side of more dark than more light. I would probably do it over 3 days, like go on at 5 pm the first day, then 7 pm, then 10pm. I've however never tried this, but I've had my lights fail for a long period before, screwing with my schedule with no I'll effect.