Late bedtimes, light at night could turn your kid into a ‘night owl’

In the study, 21 healthy children followed their regular sleep schedules for four days. They wore wrist devices that tracked body movements, and donned light meters—on Disney-themed lanyards—that monitored light intensity in their surroundings. On the fifth day, researchers made house calls and, under dim-light conditions, collected saliva samples, which were used to measure the hormone melatonin.