A daylight saving switch survival guide.

Tom Avril, Inquirer Staff Writer

“What you’re dealing with is a misalignment of your internal circadian rhythm and the external environment,” Gehrman said.

There are ways to minimize the ill effects of this congressionally mandated clock adjustment, said Gehrman, who treats patients with longer-lasting sleep issues at the Penn Sleep Clinic.

But first, a not-so-fun fact.

While the depths of winter are known for their lightless mornings, things are just as bad in late October – if not a bit worse, depending on your location – ever since Congress extended daylight saving time until the first Sunday in November.

In Philadelphia, the latest sunrise of the year comes Saturday, at 7:28 a.m., according to the U.S. Naval Observatory.

Trick or treat?

Then there is a respite. We gain an hour the next day with the return to standard time, going back to pre-7 a.m. sunrises for several weeks.

But the sun continues its inexorable retreat, showing its face later and later each day, until early January, rising at 7:23 a.m.

You might think the low point would come on the winter solstice – the shortest day, generally Dec. 21 or 22 – but no, says Rider University astronomer John Bochanski.

That is because our human construct of the 24-hour day does not align perfectly with the celestial interplay of the Earth and sun, said Bochanski, an assistant professor of physics at the Lawrenceville, N.J., school.

At certain times of year, the Earth needs a bit more than 24 hours to complete a full rotation – as measured by the time between when the sun reaches its “highest” point on consecutive days – and at other times it takes a bit less.

It is enough to make your head spin, but the result is that the time of sunrise does not start trending earlier until after the New Year.

“Really, we’re going to be waiting until January,” Bochanski said.

In the meantime, what to do about the end of daylight saving time this weekend?

There are two primary strategies, said Penn’s Gehrman.

One: as much as possible, stick to a routine.

“If you normally get up at 7 o’clock in the morning, try to get up at 7 o’clock after the time change as well,” he said.

In other words, get up at the “new” 7 o’clock, which means an extra hour of sleep that first night.

(Alas, research suggests that people fail to heed this advice. In a series of studies described in a 2013 issue of the journal Sleep Medicine Reviews, scientists found most people sleep the same amount that night, and experience a net loss of sleep during the following week.)

So let’s move on to Gehrman’s step two:

In the morning, sit near a sunny window, to help the brain reset to the shifting schedule. Failing that, seek out exposure to bright artificial light, he said.

“That kind of sends a cue to our clocks to reset for the day,” Gehrman said.

Our internal clocks, that is.

But for some, nothing will make the morning palatable.

Bochanski teaches a physics class at Rider at 8 a.m., which he acknowledges is rough on the typical 19- or 20-year-old’s system.

“Given the choice, I think they would pick a different time,” he said. “Those are the cards they’re dealt right now.”