For Prairie Park School Principal David Williams, the effect of daylight saving time is visible in the heavy footfalls of students as they trudge in the school door.

“If it’s cold and dark in the morning, it’s really tough,” said Williams, whose school bell rings at the stroke of 7:50 a.m. – 10 minutes ahead of other early-start schools. “The students are just a little bit sluggish.”

That ritual of an hour’s lost sleep followed by pressure to head out into the cold, dark morning is coming soon. The clocks will spring ahead one hour Sunday as we enter daylight saving time. At 2 a.m. local time, clocks will be set to 3 a.m.

Many profess to not noticing the event.

But the changing of the clock disrupts the body’s internal rhythm and can rob rest time from an already sleep-deprived populace, said Bob Whitman, director of the Sleep Disorders Center at Kansas University Hospital.

“We’re Americans – we’re borderline sleep-deprived anyway,” Whitman said. “We’re not really getting the seven to nine hours on average that we should be getting.”

For someone who already is not getting enough sleep, to lose yet another hour can have a significant impact on energy levels, he said.

But it is possible to lessen the potential shock by changing sleeping habits in the walk-up to daylight saving time, Whitman said. For example, going to bed 15 minutes earlier each night for the remaining nights prior to daylight saving time is one way to ease into the new schedule.

Whitman said he has not seen good evidence for the effectiveness of melatonin – a hormone that some people take to help reset the body’s internal clock.

At Prairie Park School, Williams said the school sends reminders of the upcoming clock change in its newsletter. And staff work to keep kids moving during those sluggish mornings.

While the start of the days may be challenging, there are the afternoons to look forward to, said Emily Willis, owner of Salon Hawk on KU’s campus.

“I like to get off work and have it still be light,” she said. The change “makes me feel really tired in the morning, but it lets me get a lot more done in the evening.”