Wearable sleep trackers may help you measure hours asleep but experts ask how accurate they are, how useful the data is and even what good sleep looks like Wearable sleep trackers may help you measure hours asleep but experts ask how accurate they are, how useful the data is and even what good sleep looks like T he first thing Annie and her partner do when they wake up in the morning is ask each other how well they slept. “And I literally say, ‘I’m not sure yet, let me check,’” – and Annie, a