I've done the oil/juice at 11 pm many times and always had good results. There may be a reason for the timing given; but I think our own natural timing is just as important to a successful flush as the so-called "liver times" our bodies are supposed to have. If you can't relax and sleep, you're more apt to move and be restless, and that may hinder the flush. The latest I ever took the oil was two weeks ago on my 20th flush. Because of a late doctors appointment I couldn't take the oil until after 11:30 pm. The next morning I passed over 500 stones of all sizes.