Si Koo Kim leads American Express with Scheffler and teenager Blades Brown 1 shot behind.

LA QUINTA, Calif. (AP) — Blades Brown handled the scariest tee shot at PGA West to an island green like a seasoned pro Saturday in The American Express. And then he looked the part of an 18-year-old, finding a young fan along the ropes for a game of “paper, scissors, rocks” as he headed toward the green.

The teen is having a blast in the California desert, and it could get even better.

He goes into the final round one shot behind Si Woo Kim — another teen prodigy from a generation ago — and tied with none other than Scottie Scheffler, the No. 1 player in the world.

Pressure? It didn't look like it. Didn't sound like it, either.

“I’m 18 years old playing on the PGA Tour. How awesome is that?” Brown said. “I finished high school about two weeks ago, so it’s nice to have that burden off my back, but I’m really looking forward to tomorrow.”

Kim, who was 17 when he made it through the final version of the old Q-school in 2012, quietly went about his business at La Quinta Country Club with a 6-under 66 to grab a one-shot lead, a good day to be at one of the easier courses when the wind finally arrived in the Coachella Valley.

Kim was at 22-under 194.

Scheffler and Brown were on the tough Stadium Course at PGA West — even tougher with the fan turned on — and each shot a 68 with a finish that was vastly different.

Brown, playing an hour-and-a-half ahead, finished off his round with three straight birdies, the one from 25 feet on the island-green 17th and from 45 feet on the final hole.

“Hooped two putts coming in, and that was cool,” he said. (He also won the game with the kid on the fifth try — rock beats scissors).

Scheffler didn't have a lot of close birdie chances with a wedge in hand (the wind and firmest set of greens had a lot to do with that) but he hit two of his best shots with a drive that covered the bunker and a 5-iron into the dangerous green on the par-5 16th.

“Probably the best shot of the day,” he said.

That set up birdie, and then he escaped a tough lie in dormant grass by holing a 25-foot par putt.

For a sport that has 165 years of championship golf behind it, the records can be a little messy. Brown could become the youngest winner in nearly a century, probably longer.

Charles Kocsis won the Michigan Open in 1931 at 18 years, six months — a couple of months younger than Brown — but that tournament was regarded as a regional event. Young Tom Morris won his first British Open in 1868 at age 17.

Regardless, it would be phenomenal feat, and that's without the road here.

With all the attention on his age, Scheffler was more impressed with Brown playing his eighth round in as many days on Sunday. Brown played the Korn Ferry Tour event in the Bahamas (a tie for 17th) that ended Wednesday. He tapped in, showered, got use of a private jet to fly that night to California and arrived at his hotel about 14 hours before his tee time.

And then he competed against the strongest field in some three decades at The American Express.

“I don't think people understand how difficult that is to do,” Scheffler said. He doesn't know a lot about Brown except to say, “Obviously, he's got a lot of talent.”

Brown didn't look the least bit fatigued not at his age and this chance in front of him.

“I feel great,” Brown said. “I got another opportunity to see what we can make happen tomorrow. Got another 18 holes and, yeah, should be fun.”

The other two guys in the final group should have plenty of fun, too. Scheffler helped get Kim a membership at Royal Oaks in Dallas, and they are regulars on the weekend game. They competed plenty in the month leading to The American Express.

Scheffler confirmed Kim beat him the last time they played by adding, “Yes, I gave him back a little of his money.” Scottie always keeps score.

Kim finished at La Quinta and said he wanted mainly to have fun on Sunday, which was followed quickly by a query: “Am I playing with Scottie?”

“Hopefully playing with Scottie, and we can have some fun,” Kim said.

It was PGA West some 13 years ago that a 17-year-old Kim made it through the last edition of the old Q-school, having to wait until he was 18 to join the PGA Tour. He was 21 when he captured The Players Championship, one of his four tour victories. He has become a favorite of most players.

“Have you ever spent any time with him? He's hilarious,” Scheffler said.

Sunday might be all business, and they all know enough about this tournament not to get wrapped up in the final group. Scores have been low even in a difficult wind.

Former U.S. Open champion Wyndham Clark, who can go low without notice, and Eric Cole each shot 66 at La Quinta and were two shots behind. Another shot back was Tom Hoge, who had a 65 at La Quinta. Nine players in all were separated by four shots.

AP golf: https://apnews.com/hub/golf

Blades Brown misses a birdie putt at the second hole during the third round of the American Express golf event on the Pete Dye Stadium Course at PGA West Saturday, Jan. 24, 2026, in La Quinta, Calif. (AP Photo/Ross D. Franklin)

Scottie Scheffler reaches up to catch his golf ball his caddie tossed to him at the 18th green during the third round of the American Express golf event on the Pete Dye Stadium Course at PGA West Saturday, Jan. 24, 2026, in La Quinta, Calif. (AP Photo/Ross D. Franklin)

Blades Brown celebrates a birdie putt at the 18th green during the third round of the American Express golf event on the Pete Dye Stadium Course at PGA West Saturday, Jan. 24, 2026, in La Quinta, Calif. (AP Photo/Ross D. Franklin)

Si Woo Kim, of South Korea, hits his tee shot at the third hole during the second round of the American Express golf event at the Pete Dye Stadium Course at PGA West Friday, Jan. 23, 2026, in La Quinta, Calif. (AP Photo/Ross D. Franklin)

Scottie Scheffler pumps his fist after making a par on the 18th hole during the third round of the American Express golf event on the Pete Dye Stadium Course at PGA West Saturday, Jan. 24, 2026, in La Quinta, Calif. (AP Photo/Ross D. Franklin)

ATLANTA (AP) — Your watch says you had three hours of deep sleep. Should you believe it?

Millions of people rely on phone apps and wearable devices like rings, smartwatches and sensors to monitor how well they're sleeping, but these trackers don’t necessarily measure sleep directly. Instead, they infer states of slumber from signals like heart rate and movement, raising questions about how reliable the information is and how seriously it should be taken.

The U.S. sleep-tracking devices market generated about $5 billion in 2023 and is expected to double in revenue by 2030, according to market research firm Grand View Research. As the devices continue to gain popularity, experts say it is important to understand what they can and cannot tell you, and how their data should be used.

Here's a look at the technology — and why one expert thinks its full potential has yet to be realized.

Whether it's an Apple Watch, a Fitbit, an Oura Ring or one of innumerable other competitors, health and fitness trackers largely take the same basic approach by recording the wearer's movements and heart rate while at rest, according to Daniel Forger, a University of Michigan math professor who researches the science behind sleep wearables.

The algorithms used by major brands have become highly accurate for determining when someone is asleep, Forger said. The devices are also somewhat helpful for estimating sleep stages, though an in-lab study would be more precise, he said.

“If you really want to know definitively how much non-REM sleep you’re having versus REM sleep, that’s where the in-lab studies really excel,” Forger said.

Dr. Chantale Branson, a neurologist and professor at the Morehouse School of Medicine, said she frequently has patients showing up with sleep scores from fitness trackers in hand, sometimes fixated on granular details such as how much REM sleep they got on a certain night.

Branson says those patients are taking the wrong approach: the devices help highlight trends over time but should not be viewed as a definitive measure of one's sleep health. Nor should any single night's data be seen as significant.

“We would have believed them with or without the device and worked on trying to figure out why they can't sleep — and that is what the wearables do not do,” she said.

Branson said she thinks people who check their sleep statistics every morning would be better served by spending their efforts on “sleep hygiene” such as creating a relaxing bedtime routine, avoiding screens before bed and making sure their sleep environment is comfortable. She advises those concerned about their sleep to consult a clinician before spending money on a wearable.

Forger takes a more favorable view toward the devices, which he says help keep the overlooked importance of sleep front of mind. He recommends them even for people without significant sleep issues, saying they can offer insights that help users fine-tune their routines and feel more alert during the day.

“Seeing if your biological clock is in sync is a huge benefit because even if you’re giving yourself the right amount of time, if you’re sleeping at the wrong times, the sleep won’t be as efficient,” Forger said.

Kate Stoye, an Atlanta-area middle school teacher, bought an Oura Ring last summer, having heard positive things from friends who used it as a fertility tracker: “It’s so accurate,” she said. Stoye found the ring to be just as helpful with tracking her sleep. After noticing that the few nights she drank alcohol coincided with poorer sleep quality, she decided to give up alcohol.

“I don’t see much reason to drink if I know that it’s going to affect how I feel,” said Stoye, who always wears her device except when she is playing tennis or needs to charge it.

Another trend she says she detected in the ring's data: the importance of not eating too late if she wants to get good rest.

“I always struggle with going to bed, and it’s often because I eat late at night,” Stoye said. “I know that about myself, and it knows it too.”

Mai Barreneche, who works in advertising in New York City, used to wear her Oura Ring constantly. She said it helped her develop good sleep habits and encouraged her to maintain a daily morning exercise regimen. But as a metric-driven person, she became "obsessed" enough with her nightly sleep scores that it began to cause her anxiety — a modern condition that researchers have dubbed “orthosomnia.”

“I remember I would go to bed thinking about the score I was going to get in the morning,” Barreneche said.

Barreneche decided not to wear her ring on a beach vacation a few years ago, and when she returned home, she never put it back on. She said she has maintained the good habits the device pointed her toward, but no longer wants the stress of monitoring her nightly scores.

Branson, of the Morehouse School of Medicine, said she's observed similar score-induced anxiety as a recurring issue for some patients, particularly those who set goals to achieve a certain amount of REM sleep or who shared their nightly scores with friends using the same device. Comparing sleep types and stages is ill-advised since individual needs vary by age, genetics and other factors, she said.

“These devices are supposed to help you," Branson said. "And if you feel anxious or worried or frustrated about it, then it’s not helpful, and you should really talk to a professional.”

Forger thinks the promise of wearables has been underestimated, with emerging research suggesting the devices could one day be designed to help detect infections before symptoms appear and to flag sleep pattern changes that may signal the onset of depression or an increased risk of relapse.

“The body is making these really interesting and really important decisions that we’re not aware of to keep us healthy and active and alert at the right times of day,” he said. “If you have an infection, that rhythm very quickly starts to disappear because the body goes into overdrive to start fighting the infection. Those are the kind of things we can pick up.”

The technology could be particularly useful in low-resource communities, where wearables could help health issues to be identified more quickly and monitored remotely without requiring access to doctors or specialized clinics, according to Forger.

“There’s this really important story that’s about to come out: About just how understanding sleep rhythms and sleep architecture is going to generally improve our lives,” he said.

A patient room for sleep research is seen at the Morehouse School of Medicine Friday, Jan. 16, 2026, in Atlanta, Ga. (AP Photo/Emilie Megnien)

Dr. Chantale Branson, a sleep neurologist at the Morehouse School of Medicine, stands for a portrait, Friday, Jan. 16, 2026, in Atlanta, Ga. (AP Photo/Emilie Megnien)

Wearable devices, including Apple Watches, can be used to track sleep, Wednesday, Jan. 21, 2026, in Atlanta, Ga. (AP Photo/Emilie Megnien)

Middle school teacher Kate Stoye puts on an Oura ring, a wearable sleep tracking device, Wednesday, Jan. 7, 2026, in Hiram, Ga. (AP Photo/Emilie Megnien)

Middle school teacher Kate Stoye checks her sleep score on her phone, Wednesday, Jan. 7, 2026, in Hiram, Ga. (AP Photo/Emilie Megnien)