Here is more scientific data to back up plant growth at night (with references). Thanks for playing!

Biologists Identify Genes Controlling Rhythmic Plant Growth

While most people might assume that plants grow at a slow and steady rate throughout the day and night, Darwin and others found that they grow in regular nightly spurts, with plant stems elongating fastest in the hours just before dawn. See video of soybean sprout growth at: http://www.biology.ucsd.edu/scicomm/video/bigbeansprout.mov
"Plants actually grow rhythmically," said Kay. "Some plants, like sorghum, have the ability to elongate a centimeter or more each night."
Why plants have evolved mechanisms to grow rhythmically at night or in the hours just before dawn is a mystery. But a similar interplay of light sensing, plant hormones and circadian rhythms that leads to a pronounced rhythmic growth by plants during certain seasons and when shaded by other plants has a clear survival value.

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GreenThumbDoc Reviewed by GreenThumbDoc on . would like opinions on seedling light schedule just started my first indoor grow- been doing it outside since 1972- got a lot to learn for-sure I have started my seeds , sprouting today- I have them under a 1k MH , I am able to maintain a 72 degree temp 24 inches from tops- should I be running a 20 on 4 off for now- or should I be doing a 16 on 8 off then switch to 20-4 after roots are established- googled this ? and got a bunch of different opinions on using MH at this stage, it is what I have for now HELP !:thumbsup: Rating: 5