An exercise paradox: a walk wakes you up, but hard training will run you down.
...sleep specialists often tell people with insomnia to exercise five to six hours before bedtime. The mild exercise raises the body’s core temperature. When the temperature falls again a few hours later, that signals the body to sleep.
But that is a different sort of exercise from what endurance athletes do, and so what happens to marathoners-in-training must have another explanation. One possibility, Dr. Chediak said, is th...
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