Light issue, drooping leaves?

Can low light cause the leaves to droop simply from not enough light?
My plants are doing great but my 400watt HPS set up hasnt arrived yet but will thursday but my plants went through a huge growth spurt in 6 days went from 12" to almost 23" so now my 6 48" cool white flouros are nowhere near enough and some of the leaves started wilting and was wondering if that can be just because of the lack of light and if so will it be ok for 2 days or so until the real light arrives and if so should i wait till they recover before going 12/12 because they are already 26" tall
conditions, soil(stinkys mix:thumbsup:), ph right on 6.7ish, drainage great, temps 75-80, humidity 45%, lights UNDERpowered mentioned above.
thanks in advance for all the knowledge I know is coming

Entirely possible; I've seen symptoms that were slight, but almost like overwatering (slight droop, yellow low leaves) because the plant simply isn't getting enough 'juice' to go through the moisture available to it. And the lower leaves WILL yellow and drop if there isn't enough light getting to them.

In my flouro-powered clone storage closet, I keep the rooted clones very much on the dry side (in that exact soil mix actually) until I need them.