Lighting Advice

I have 4 plant's going, between 3 - 5 inches tall now. I have a T5 8 flourencent bulb (40,000 lumens i bealive) light haning aprox 2 - 4 inches above the plants. for the last week sence they poped up I have the light on 24/7 on them and 1 of the plants wilterd over last night and I proped it up with a straw and twist tie. I think it is top heavy. Should I switch the light cycle to 18/6????

if they are blooming, unless you're growing autoflowering plants, switch to a 12/12 light cycle and make sure you're using a lower kelvin rating light (2100-2700k) for maximum results

I would raise your light. I too use (right now) 4' 8 bulb T5s and I only have the 4 lights on in the middle and they are 12" above. When I turn on all 8 bulbs the seedlings lean over. Also I have them on 20/4. If I where not organic I would have them on 24/0 for the first 2 weeks then I would go 20/4.

You need more light and a fan blowing on them to toughen the stem.

switch them to 12/12? not sure why he would do that if they are only 5" tall. But i would definately get a small oscilating fan to help strengthen them up.
Just think, in nature they have a lot of wind. Also make sure that you are watering them properly with the right PH water. Good Luck