Upside down leaves!? *first grow*

[elmo17]

I'm about a week away from 12/12. My veg room has 3 lights, 2 x CFL 250w and 1 HPS 600w. Now the plants are older, every time I put one under the HPS its drooping and on one strain the leaves are actually turning around.. I'm worried as when I turn to 12/12 next week, all three bulbs will be changed to 600w HPS.

Any advice massively appreciated, thanks!