Technology Every Breath You Take Now a high-tech shirt can record your vital signs all day and night By Mark Alpert THIS IS A PREVIEW. Buy this digital issue or subscribe to access the full article. Already a subscriber or purchased this issue? Sign In JOHN FRASER I've been a hypochondriac ever since I was a kid. As an eight-year-old, I was terrified of having a heart attack, and no amount of parental reassurance could erase this fear. In my childish reasoning, these worries seemed perfectly logical--heart attacks were the most common cause of death in my family, and they appeared to strike without much warning. At my most panicky moments in the middle of the night, the only way I could fall asleep was if I kept my hand pressed against my sternum to convince myself that my heart was still beating. When I confessed these anxieties to my father, he tried to point out the ridiculousness of my behavior by suggesting another method of self-diagnosis: "You should also stick a finger in your nose to see if you're still breathing." My hypochondria has eased a bit over the past 35 years--now I worry more about my kids' health, freaking out over every sniffle and scrape. But I recently discovered that monitoring heart rate and breathing during sleep is not such a ridiculous idea after all. More than 12 million Americans suffer from sleep apnea, a disorder characterized by frequent interruptions of breathing. The cause can be either obstructive--a temporary closing of the soft tissues around the airway--or neurological; in both cases, the condition forces the sleeper to awake briefly to resume breathing, as many as 400 times in a single night. If left untreated, the disorder can raise the risk of cardiovascular problems, but the great majority of sufferers simply endure their nightly struggles and constant fatigue. One obstacle is that doctors cannot definitively diagnose sleep apnea unless the patient spends a night under observation in a sleep lab. THIS IS A PREVIEW. Buy this digital issue or subscribe to access the full article. Already a subscriber or purchased this issue? Sign In Buy Digital Issue $7.99 Add To Cart Print + DigitalAll Access $99.99 Subscribe ADVERTISEMENT Scientific American is a trademark of Scientific American, Inc., used with permission © 2015 Scientific American, a Division of Nature America, Inc. All Rights Reserved.