How Exercise Helps (and Hurts) Sleep  A single workout won't fix
your sleep problems, but a consistent habit might.  August 21,
2013  Exercise helps you sleep better, right? That's the
conventional wisdom, and has certainly been my experience. But
for others, the opposite seems to be true. An interesting new
study in the Journal of Clinical Sleep Medicine offers an
explanation for this apparent paradox, as Gretchen Reynolds
reported in the New York Times today.  Actually, it's a
reanalysis of the data from an earlier study by researchers at
Northwestern. That initial study produced the expected result: a
group of sedentary older adults with persistent insomnia did
three days a week of aerobic exercise for 16 weeks, and by the
end they reported better sleep quality and were getting an extra
45 minutes of sleep per night compared to the control group.
Wonderful.  But a closer look at the data reveals some
surprises. For one thing, there was no link between the amount
of the exercise the subjects did on any give