It's 7:20 p.m. and Sean is bent over physics homework, graphs that show position and velocity in relation to time. Motion maps.
The work isn't particularly difficult for him. The challenge is staying focused.
"The more I think," he says, "the more irritated I feel."
Sean is my 17-year-old son. He's a high school senior and a good student.
But he's tired.
If you ask him what he looks forward to on weekends, he'll give you the same answer many teens do: Sleeping.
Instead of the eight-and-a-half to nine-and-a-half hours of sleep research has found teens need to perform at their best, Sean averages six to seven each night. Even though he sometimes slips into bed at 9:30 or 10, he usually can't fall asleep until 11, and he's at school most mornings by 5:45 for weight sessions with his baseball team. Classes begin at 7:35.
We are a tired country.
The Centers for Disease Control and Prevention has called insufficient sleep a public health epidemic, noting in a 2009 study almost 38 percent of adults had unintentionally fallen asleep during the day at least once in the preceding month and nearly 5 percent had fallen asleep while driving at least once during the same time period.
Scary. But not surprising.
Like the one-third of adults in the study, I, too, consistently sleep less than the recommended seven hours a day and often find myself longing for just a few minutes in which to rest my eyes.
The real calamity, though, is the sleep deprivation of our teenage children, who as a generation are losing the opportunity to achieve their highest potential, simply because they don't have the few more hours needed to recharge.
"Sleep is absolutely vital, not just from a physical standpoint, but from a mental, emotional and cognitive standpoint," says Steve Portenga, a performance psychologist who teaches at the University of Denver and helps athletes, surgeons and others in high-risk occupations perform consistently at their highest levels.
A key element to that formula is sleep.
Sean would agree.
On days when he's tired, "it's hard to focus. I just catch myself spacing," he says. But when he feels rested, "it's easier to participate in class - you feel more in it. It's easier to comprehend and retain information ... I'm just more aware, in general."
Portenga talks about two studies that directly link sleep to performance.
In the first, two groups of people were given 12 hours to solve a difficult problem. One group received the problem in the morning, so didn't sleep before resolving it that evening. The other group received it in the evening, so had the opportunity to sleep before coming up with an answer.
"Both had the same amount of time to solve it ..." Portenga said, "but the ones who had a chance to sleep performed significantly better."
In the second study, electrodes were connected to the brains of mice as they figured out a way through a maze. As the mice slept, researchers noted the same series of connections firing as had occurred when they navigated the maze. The mice were replaying their route; the brain was moving information from short-term to long-term memory, which makes retrieving information easier down the road.
The study showed, Portenga says, that "for consolidating learning, sleep is a really vital process."
With that knowledge in mind, the American Academy of Pediatrics, saying the average American teen is "chronically sleep deprived and pathologically sleepy," last week declared middle- and high-schoolers should begin their day at 8:30 a.m. at the earliest - essentially an hour later than most do now. Such a change would align with teens' natural sleep cycles, which make it difficult for them - like Sean - to fall asleep before 11 p.m. And it would be key to helping "adolescents get the sleep they need to grow and learn."
According to a National Sleep Foundation poll, 87 percent of high school students and 59 percent of sixth- through eighth-graders were sleeping less than the recommended eight-and-a-half to nine-and-a-half hours a night. Reasons range from sports, after-school activities, jobs and homework to over-active technology use.
The academy's policy statement noted lack of sleep in teens not only translates to a decrease in learning and poorer grades, but also to more physical and mental health problems and an increased risk of car accidents.
Scary. But not surprising.
Senior Craig Breuker can attest to the positive impact of a later starting time.
His first class this semester starts with second period, which means he begins classes at 8:30. The difference from previous years is stark.
"When I wake up, I just feel refreshed," he says. "When I used to wake up at 6:30, I would always feel down and groggy. I haven't had a morning where I feel like I want to go back to bed. When I get up, I'm ready for the day to start."
He's more focused. He has more energy later in the day. His eyes don't get heavy.
An A and B student, Craig practices soccer after school until 5:15, then mows lawns until dusk, then finally heads home to do homework. If there's time, he'll watch some TV until turning off the lights at about 10:30.
Going to bed, he says, "is like a restart."
But considering only 15 percent of our country's high schools begin the day at 8:30 or later, Craig's sense of rested well-being belongs to a minority of teens.
There is a long way to go.
School district schedules are built around a complexity of ingredients, from bus schedules to athletics to extracurricular activities, and a realignment of all those pieces would need buy-in from not only school officials, but also from parents and teens, themselves.
Until the paradigm shifts, until we are willing to take on the challenge - if we ever are - days for many teens will begin somewhat like this:
5 a.m. The first alarm goes off. Music blares. Sean reaches over and turns it off.
5:10 a.m. Music blares again. Unwilling to leave the warmth of his bed, Sean reaches over and sets a third alarm for 10 minutes later.
5:20 a.m. More music. Five more minutes tick by and his feet hit the floor. He throws on a T-shirt, some shorts, shoes. Brushes his teeth. Washes his face.
He grabs a water bottle and heads out the door.
It is still dark, the notion of sleep already forgotten.
Ann Macari Healey's column about people, places and issues of everyday life appears every other week. Her column earned first place in the 2013 Colorado Press Association Better Newspaper contest. She can be reached at firstname.lastname@example.org or 303-566-4110.