Plant is happy with lights off, sad with lights on.

Self explanatory I wanna know if this is normal or what. But for the past few days I've been vegging till earlier this morning I switch to 12/12 when I cut the lights back on she was more perky then ever all the leaves were up straight. But after a few hours they've drooped back down.. does anyone know the cause to this or why it's happening? I also have white spots and dead tips. I've checked with a magnifying glass see no bugs or anything. I'm not using any nutes. Will provide pics if asked. By up straight I mean just out stretched like your hand

are you growing indoors/outdoors? sounds like its heat stress when the heat isn't there it comes back to life when its there the plant gets to hot and falls over my bet would be heat stress try moving lights further away if indoors if outdoors dont keep it in direct sunlight all day and if the temp is above 90 you need to put it in the shade because thats to hot. i had this problem with my outdoor plants it gets about 8 hours sunlight 2-3 hours shade now and it fixed my problem. direct light all day is not in a plants natural habitat so it can cause problems at some point in the day its generally getting shade from something keep it natural ... Good luck!!