Health & Fitness  Put your stress on vacation  Got stress?  If
you answered no, hooray for you! (And, by the way, what planet
are you from?)  But if you answered yes (like any normal member
of the human race), you're likely heartened by the arrival of
vacation season. Just the ticket for a little stress-reduction.
And that can have some big payoffs. It can lower your blood
pressure, boost your immune system and help you live longer. It
may even make you smarter.  "A vacation is not a luxury," says
Jens Pruessner, an associate professor in the departments of
psychology, psychiatry, neurology and neurosurgery at McGill
University in Montreal. "It's an investment in your health."
Most of what scientists know about the brain and chronic stress
comes from studies of rodents, whose response systems are very
much like ours (perhaps disconcertingly so) and who therefore
make good stand-ins for us. But rodents rarely pack their bags
and head for the beach when summer rolls around, so it's harder
to use them as model