...I know, cuz I've kinda baked my girls a bit on a couple of occasions.

I initially set my lights to come on at 9am, and off at 3am, to 'mirror' what might be construed as 'normal' electricity usage times, but I found that during the day, especially around suppertime, the closet was too dang hot, and I couldn't get the temp down even with more fans.

I then gave the girls a long sleep one night, and reset it so that my lights come on at 8pm at night, and were on until 2pm the next day, thereby being off during the hottest part of my day.

Moving to 12/12, the lights now run from 8pm to 8am, and temps are fine (averaging 76 to a 'hottest' of 82-83 on occasion), though we've been 'blessed' with an unnaturally cold late spring / early summer up here in TO. If I had to fight hot ambient air like last summer, I might have to buy a small air conditioner.

Try shifting your lights to begin just as it's cooling off for the day (unless they're already that way)... hope this helps!