That time of year, Daylight Saving Time, is back.

Officially, it’s when clocks indeed spring forward, converting CST (Central Standard Time) into CDT (Central Daylight Time).

With it comes the delightful delusion that each day offers an extra hour of sunlight—a welcomed midyear promise that night will no longer beat us home from work.

But the delusion is not without a price, and for remarkably many people, DST carries a minor, yet genuine, malaise that could be called “Poor Man’s Jetlag.” That’s because shoving the clocks ahead an hour temporarily tampers with our body’s biologic beat, particularly our circadian rhythms. Those are the rhythms inside us that cycle in 24-hour intervals... Adjusting to DST can make us feel like we’ve flown across time zones when we haven’t budged an inch.

“Owls” and “Larks”

However, some people handle the changeover better than others, says Michael Smolensky, Ph.D.,professor of Environmental Physiology at University of Texas School of Public Health at Houston and co-author of The Body Clock’s Guide to Better Health.

Come Monday around the office coffee machine, early-riser “larks” might chirp through their day, while late “night-owls” stare blankly into their cups. According to Smolensky, not all body clocks—or even circadian rhythms—are created equal.

Owls function better later in the day; larks, earlier. And it is the owl who has the tougher time springing forward.

The body’s clock tends to tether its functions to 24 hour-periods before starting the cycle over again, just like the Earth’s daily rotation. But unlike the earth, we run fashionably late.

A Swiss time piece, we’re not.

“The circadian clock or rhythm doesn’t run at exactly 24 hours, but at a period slightly longer," he says.

“Some people’s circadian clocks are more extreme than others. Night owl folks have inherited body clocks with rhythms much longer than 24 hours. Their 'sleep-wake’ patterns don’t let them fall asleep until the wee hours.” Their cycle is starting over at 25- hour intervals, for instance.

A lark’s rhythm—and sleep-wake cycle-- runs much shorter than 24 hours, making their mornings come earlier.” The rest of us, he says, fall somewhere in the middle.

The night owls and the “slight” owls have a bluer Monday after DST than the rest of us, because they go to bed later anyway and wake up shorted.

“Losing an hour goes against the natural play-out of our circadian clock.” he says. “It goes against nature.”

Social Clocks

There is also a direct relationship to human society. Civilization is built around darkness and light. The body must conform somehow to group norms, simply to be productive. “The body’s master circadian clock is housed in the brain and there’s a direct neural connection between the eye and the clock.

“Being able to ‘see’ that it is day or night fine tunes the body clocks of the most extreme owls or larks.” Their clocks adjust to a 24-hour society, yet they simply prefer to sleep in or rise early.

Just One Lost Hour of Sleep…

Adults tend to be sleep-deprived in our society. If we stay up late on the weekends, Smolensky says, our biological clocks start to drift . Even under normal circumstances, Mondays are a jolt to our internal alarm clocks. Monday becomes even bluer when the body has to adjust to DST.

Then, he says, “the post-lunch dip in energy, concentration, alertness and attention becomes more profound. The loss of just that one hour of sleep can magnify these problems for a few days following the changeover to DST.”

So, too, are some children affected. “For younger children, the time change is more problematic because of regimentation imposed by school schedules,” says Smolensky. On the Monday following the DST changeover, kids may be sluggish and perform poorer on tests from that missed hour. Their circadian rhythms are not fully in tune with the demands of school.

Multi-tasking moms may suffer the most. says Smolensky. “Sleep deprivation is the key. This is not a gender-specific difference. Women tend to steal from their sleep hours to find more time. Women who work outside the home are juggling responsibilities and shaving personal sleep time, and even more work gets pushed into the night that first changeover week.”

Is There DST Auto Insurance?

European and Canadian studies link auto mishaps to DST. In Canada, research over a two-year period shows a 7-to 8 percent rise in accidents on the Monday following DST changeover,” says Smolensky.

“We are now analyzing 17 years of available data in Texas,” he says. The UT-Houston School of Public Health, along with Texas A&M University, will do their own study to determine whether there is an increase in automobile accidents immediately after changing to DST.

If research confirms suspicion, an education campaign will likely be devised to reduce public health problems that accompany the time change.

Check Those Meds

In another health venue, he says, a few patients experience difficulty in adjusting their prescription medication regimens to DST.

Insulin-dependent diabetics, for instance, who have a medical history of very specific insulin requirements should check with their doctors to be aware of, and properly deal with, any possible adverse effects of adjusting their circadian clock to DST.

For all but the most diehard of night owls, DST imposes a simple, short-lived adaptation.

“In general,” says Smolensky, “we adjust by when we see light and darkness. Adjustment is essentially automatic over the course of two or three days. It’s the same as with jetlag, only DST is faster. And far cheaper.”

UPDATED: 4-03-2003

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