Disregarding family life the optimal time to train is late evening around 11 o'clock, according to a study conducted on circadian rhythms which found that human performance was at at it's highest at this time. Obviously if human performance is at it's highest this is the optimum time to train. I myself train early evening, and late evening each session takes around 30 minutes. It works well for me, I don't have kids that I might wake up. But as per your question bulldog late evening is the best time, the worst time is early morning for a plethora of reasons, like the spine issue as mentioned before, also unless you sleep eat your energy reserves are going to be pretty low, and it takes a while to replenish your reserves. So the later you train the better provided your well nourished and hydrated, I try to drink a liter or two before bed so I'm not too hypohydrated in the morning. Not everyone can train late evening but as far as human performance goes it is the best time, therefore if you were wanting to lift as much as you can the best time is late evening. I have the study on file somewhere, I will try and find it, and post the author and title sorry but it is a hard-copy.
Hope I've answered your question Bulldog. If you can train late do, but if you cannot, keep training because it still works.
Kind Regards Ryan