changing lights due to emergency

due to a very rare thing at work my shift has changed completely and my lights on/off were based off that pretty much 7pm-7am as i worked all day an night off but now its the opposite and its making it very diffacult to keep the same care in that room as it needs any adivce on switching the lights i know it will shock them i plan on doing it in one day but how should i do it what can happen, if i leave the lghts off all day thrn switch then on at 7am or let the lights stay on for a 24 hours cycle then off and start 12/12 from there

Go one extra dark period. No big deal.

bugeye is correct skip the light cycle and change it to what you want . do not go 24 with the light .