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 nybody who's flown home to Canada through several times zones knows how easy
it is to throw our internal clocks out of whack. All the restful effects of
that wonderful trip to France can be wiped out after the plane ride home to
Lethbridge or Halifax or Ottawa. But surprisingly, even something as seemingly
insignificant as an hour's change in time can wreak a little temporary havoc.
Twice a year, in April and October, we change our external clocks -- ahead an hour
in spring and back an hour in fall -- to realign our schedules with Mother Nature's.
Ironically, though, losing or gaining an hour in our day goes against our
own nature -- something that's often easier to see in really young children,
as they try to adjust to the time change, than it is to recognize in our own
usually sleep-deprived selves.
What makes us tick
The internal clock, which is known as circadian rhythm, runs for a period of
just slightly longer than 24 hours. In fact, researchers have shown that if
people are left to their own devices and are given no environmental cues as
to the time of day, most will fall into a 25-hour-day pattern. The circadian
clock, the part of us that literally makes us tick, is located at the base of
the brain and takes up a relatively small area, but it times pretty much
everything that happens in the body based on the daily cycle of light and
dark.
Night owls -- people who function well later into the night -- have a longer circadian
rhythm than morning people, who hop out of bed early and tackle the day. That
longer rhythm means their internal clocks have to make adjustments every day
simply to fit in to a 24-hour-day world. Indeed, more likely than not, it's
the night owls who are the grumpiest on Monday mornings simply because they're
more likely to have stayed up and slept in later than normal on the weekend.
Add another time change on top of it and it's no wonder the body gets thrown
for a loop.
Stumbles and slumps
Still doesn't seem too serious? Some studies show increases in accidents at
work and on the roads in the day following a time change. In fact, research
done over two years by Stanley Coren, a neuropsychologist at the University
of British Columbia, concluded that car accidents in Canada increase by about
seven per cent after the changeover in spring when people are functioning
on an hour's less sleep than usual. One year, the number of accidents on Canadian
roads was 2,590 the week before the time change; the week after, that number
increased by 200. Coren, author of the book The Sleep Thieves, also noted that
the accident rates decreased after the October changeover, when people got an
extra hour.
But fortunately, for all but the most committed night owls and the already
sleep-deprived, the transition to Daylight Savings Time isn't too horrible.
Sure, it might mean a more pronounced mid-afternoon slump in energy and
ability to concentrate for a few days. It may mean crankier kids, who are tied
to an unforgiving school or nap schedule. For most of us, however, it doesn't
get too much worse than that.
If you can't bring yourself to hit the sack a little earlier for a few nights
leading up to the time change, take heart: it only happens twice a year -- and
at least this time change offers the possibility of an extra hour's sleep.
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This article was prepared by Nora Underwood for 
