If you exercise in the morning it gets out of the way, you feel energetic and it’s a big accomplishment for the rest of day. Exercising makes you happy, elevates heart rate for the rest of the day, and if you exercise in a fasting mode you also are depleting body’s energy instead of the food one.
If you exercise in the evening, your heart reta is elevated during the day so it might be easier way with cardio. It helps to use up extra energy you have left, might relax you and help to wind down. It’s important to left enough time before to sleep otherwise you might have difficulties falling asleep. It’s best to choose something relaxing/low impact if you exercise right before sleep time.
The most important is not when you do it, but that you do it. There are many variables in life so as long as you do your workout it will be effective either way.
I hope it helps.
I do it before breakfast is because after breakfast I have to let the food digest and that will take time. When I start doing yoga, it’s already sometime into the middle of the morning. In order to have a block of time to do other things, I choose to do yoga in the early morning. Also I found, right after bed, the body is more stiff so it’s good to have a stretch.
For bedtime yoga, I found a little bit of stretching to enhance the muscles and then relax the muscles, I will sleep better.