NASHVILLE, Tenn. (AP) - Charlie Byrum is a guy who understands getting up early.
Just like clockwork, Byrum arises at 3 a.m., seven days a week, and heads to work to begin cooking breakfast sandwiches at his Nashville convenience store, Drew's Market.
Asked if the switch to standard time from daylight saving time this weekend will let him sleep in, Byrum replied, "I'll wake up anyway."
AP Photo - - The time change out of Daylight Savings Time this weekend doesn’t always mean an extra hour of sleep. People’s body clocks don’t always adjust overnight to what the alarm clock says.
Dr. Beth Malow, the director of the Vanderbilt Sleep Disorders Center at Vanderbilt University, says Byrum isn't alone.
While the time will change at 2 a.m. Sunday, our bodies need more, well, time to adjust, Malow said.
As for getting that extra hour of sleep when the clock "falls back" in autumn, she said while some may feel a benefit, many more won't and the effects last long beyond Sunday morning.
"We're trying to get the kids to bed and we see the clock and it says 9 o'clock, but it feels like 10, so we wait to go to bed," Malow said. "We're really tired the next day."
Malow, who is also a professor of neurology at the Vanderbilt University School of Medicine, said some of us don't need an alarm clock, or seldom do.
"I think some people have stronger internal clocks than others," she said.
There is also the issue of how a person is sort of hard-wired to function in different parts of the day.
"Some are night owls, some are larks," Malow said, "But we all have a sleep debt and you can't store up sleep."
The extra hour inserted Sunday also changes our habits. It's lighter out when the kids go to the school bus stop, but gets dark sooner after they come home.
A habit Tennessee Fire Marshal Leslie A. Newman champions is to get people to change the batteries in their smoke detectors when they change their clocks.
"Use that extra hour we gain this weekend to make sure your home and family are fire-safe," Newman said.
The view from the pulpit sometimes changes on the first Sunday in November.
Nate Collier, the operations minister at Broadway Christian Church in Lexington, Ky., poured over attendance figures to quantify something he's noticed.
At the large church near Transylvania University, last year's congregation on the first November Sunday was 26 percent larger than on the previous Sabbath. In 2008, attendance was up 16 percent from the week before.
Was it because congregants got that extra hour to get ready for church? Collier has his doubts.
"I think people generally stay up an hour later (on Saturday night)," he said.
Standard time began in the 1800s when it became obvious that each community setting its own official clock at high noon was no way to run a railroad. The railroads needed uniform time to publish a train schedule.
The last time Congress tinkered with time was five years ago with the Energy Policy Act of 2005. That moved the start and end dates for daylight saving time. In doing so, it rendered some bedside clocks -- sophisticated for their time -- laughably inaccurate, causing them to flip time on now-inappropriate dates.
Back at the market, Byrum turned his sausage patties on the grill and said he doesn't need an alarm clock to wake up and knows his internal clock won't immediately revert to Standard Time on Sunday.
"It'll say 'wake up' at the normal time," he lamented. "Right now, it's saying 'go back to sleep.' It says that a lot."
At the sleep disorder center, Malow said she is blessed to have her job because it can change people's lives.
Still, she said, there is sometimes stress involved, then mused, "You wouldn't think helping people sleep well would be stressful."