Leaves & branches dropping and bending.

Hi people.

I have a problem. My girl seems to drop her leaves when the light turns on (2nd day in a row). She got into flowering about a week ago. Went from 24\7 to 18\6 abit late, so she never had any darkness before. When its the nights turn, she stretches up again like a champ! But as soon as the light goes on, she starts bending branches downwords and dropping leaves.

She is`nt overwaterd or too much nutes. So, what can it be?

Dont she like the light no more?

I`ve looked everywhere, but nothing seems to give me a answer.

Hope some of you guys can help.

EDIT: Its just the one of 2 plants.

600HPS
18\6
27-30C