I am just starting to be able to exercise intermittently after starting T3 med. a few months ago. I like to ride my bike in the evening, but it's so hot now that I've been going in the morning, and it seems like it contributes to a small afternoon crash. Plus I can feel PEM creeping on after 3 days of short rides (time for a break, I hate to say). So if you are able to exercise, does it matter what time of day? Do you crash if you try to exercise out of your body's chose daily rhythm?