I would actually like my click and grow light to be on during night time hours, to function as a night light. My house is quite light during the day, so my plants (basil, cilantro, parsley) would get indirect sunlight by day and grow light by night. Would that have an adverse effect on herbs?
If you leave the lamp on during the night and also the plants get enough light during the day, you may experience leggy growth and some salad greens may tend to bold prematurely. Especially, if you have a slightly higher temperature range. It seems that herbs and ornamentals are commonly more tolerant to long day. But, as said before, it depends on what you are growing.
Just try it out and let us know how your plants performed.