The idea is undeniably appealing: Slap this strap on your wrist or clip a doodad onto your shirt, and you can monitor everything from mood to motion, optimizing each breath and step. We bought into the promise of these intriguing new health trackers, but we wanted the experts to reality-check them.

THE GOAL: Ballerina posture

Photo: Courtesy of Lumo Bodytech Inc.

THE TRACKER: Lumo Lift ($100; is an oval magnet that attaches to your shirt or bra strap and buzzes if you slump for more than, say, 15 seconds.

THE IDEA: You'll be gently reminded to sit up straight.

EXPERTS SAY: Standing (or sitting) tall is a worthy goal, says Laura Deon, MD, an assistant professor in physical medicine and rehabilitation at Chicago's Rush University Medical College. "Good posture can keep your bones and joints aligned, preventing pain and improving your mood and appearance." Keep in mind, though: To see the benefits, you'll need to wear it all the time.

THE GOAL: A more zen frame of mind

Photo: Courtesy of Garmin Ltd.

THE TRACKER: Garmin vívosport ($170; assesses stress levels by tracking heart rate variability (HRV), a measure of the variation in time between heartbeats.

THE IDEA: You check your levels to see whether stress is getting the better of you; if it is, the tracker can lead you through a slow breathing exercise designed to calm you.

EXPERTS SAY: "This is an okay source of data on HRV, which can absolutely be influenced by stress," says Richard Gevirtz, PhD, a psychology professor at San Diego's Alliant International University. And breathing exercises have been shown to help bring HRV into line. Yet HRV can be affected by many other things, like exercise, illness, depression, and fatigue, notes Gevirtz.

THE GOAL: More and better sleep

Photo: Courtesy of Fitbit, Inc.

THE TRACKER: Fitbit Alta HR ($150; is a wristband that uses an accelerometer and heart rate monitor to chart your sleep cycles.

THE IDEA: You'll see an estimate of the number of hours you spent in the phases of REM, deep, and light sleep, as well as your cumulative snooze time.

EXPERTS SAY: "It's valuable to know how much time you spend sleeping," says Katherine Sharkey, MD, PhD, an associate professor of medicine at Brown University. "But the only way to accurately tell when you're in the restorative REM phase is by looking at brain waves." If you're exhausted but your tracker confirms you're getting seven to eight hours of shut-eye, talk to a doctor about sleep disorders.

THE GOAL: Boosted mood

Photo: Courtesy of SunSprite

THE TRACKER: SunSprite ($100; clips to your shirt and uses sensors to detect exposure to bright light (from the sun or a light-therapy box).

THE IDEA: Bright light is linked to improved mood. This device tells you if you’re getting 30 minutes a day, the amount the company's experts say is enough to help us feel sunny.

EXPERTS SAY: "Research shows that many people who spend most of their time indoors need more bright light than they routinely get," says Norman Rosenthal, MD, a psychiatrist and seasonal affective disorder researcher. "Thirty minutes a day is a reasonable goal, but there's no specific amount of exposure that would benefit every person." Start with the minimum; see how you feel.

THE GOAL: A healthy heart

Photo: Courtesy of AliveCor, Inc.

THE TRACKER: KardiaBand ($199 plus $99 per year; is a wristband that attaches to an Apple Watch face to track irregular heartbeats (arrhythmias).

THE IDEA: If you're alerted that your heart rate seems too fast or slow (or if you feel like you're having palpitations), hold your thumb over the band's sensor to get an EKG reading.

EXPERTS SAY: "It's very good at detecting the arrhythmias that can increase your risk of stroke or heart failure," says Gordon Tomaselli, MD, chief of the cardiology division at Johns Hopkins University, "and can be useful if you have a diagnosed arrhythmia." For everyone else: The Apple Watch itself measures beats per minute to show how hard your heart is working.


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