The body adapts to any demands you place on it in time, whether the morning is an optimal time to train, depends on the individual.
Everyone has their own specific circadian cycles and bio-rhythms....you should train when yours allows you to perform your best. Some people are "morning people" and some are "night owls." Most people fall in between.
Seriously, if people just learned to listen to what their own bodies told them, and less to what others say, they would make much more progress.
You can gather and receive advice and input from others, but then old fashioned trial and error, will get you where you want to go, in time. Problem is, if you don't take the time to listen to and learn how your body responds, you won't be learn how to make the proper adjustments when needed.
Disrupted sleep is never a good thing