Exercise, whether am or pm, is a boon for your well being

Find the article at the link above.
A few quick notes of my own in italics:
But, Dr. Colwell says, that clock can become discombobulated. It is easily confused, for instance, by viewing artificial light in the evening, he says, when the internal clock expects darkness. Aging also worsens the clock’s functioning, he says. “By middle age, most of us start to have trouble falling asleep and staying asleep,” he says. “Then we have trouble staying awake the next day.”
Many of my clients report trouble sleeping. One of the strategies they, and I, have tried is reading ourselves back to sleep. Unfortunately, many of us use our laptop screens or our e-readers rather than print material. This artificial light might be counter-productive – just the light from an e-reader can diminish the melatonin output and contribute to our sleeplessness. Try listening to a calm radio program. My favorite is Fresh Air (WHYY). Or, reading from print material.
“What we know, right now,” he says, “is that exercise is a good idea” if you wish to sleep well and avoid the physical ailments associated with an aging or clumsy circadian rhythm. And it is possible, although not yet proven, that afternoon sessions may produce more robust results. “But any exercise is likely to be better than none,” he concludes. “And if you like morning exercise, which I do, great. Keep it up.”
This is the essential point of the article. Whether you do everything in life at its most effective time isn’t important if you’re not yet doing it at all. Just get into the habit of 15-30 minutes of increased heart rate a day, and within a week you’ll feel better in many ways: better outlook, better sleep, better energy.