'We were expecting people to watch a lot of TV,' said Dr. Mathias Basner of the University of Pennsylvania School of Medicine's department of psychiatry, one of the study's authors. But, said Basner, 'it was astonishing' to learn that even when they had to get up early for work, Americans were unlikely to pare their habit of nighttime TV. On average, Americans spent almost half of their last two waking hours of each day watching the tube. In spite of technologies that allow U.S. viewers to record and watch a show later or on hand-held devices, 'they just wait till the show ends' to turn off the tube and go to sleep, said Basner. Interestingly, he noted, those who live in the Mountain or Central time zones, where prime time is an hour earlier than on the coasts, get more sleep than those who live in the Eastern or Pacific time zones. The study findings were drawn from time logs kept by 23,193 Americans for the U.S. Bureau of Labor Statistics between 2003 and 2006. The research was presented this week at Sleep 2009, the 23rd annual meeting of the Associated Professional Sleep Societies, in Seattle. Roughly 40 percent of American adults sleep less than seven to eight hours, even though doing so raises their risk of daytime sleepiness, obesity, illness and even death. Basner and his colleagues have been exploring where Americans could wedge more shut-eye into their days, and they looked at the two hours before bedtime and the two hours after waking as the best places to add some z's. But lengthening commutes and workdays have made a delay in workers' start times unlikely, Basner said. So if Americans are going to close their yawning sleep gap, they'll need to do so either by leaving the TV off at day's end or taking the bold step of turning it off in the middle of the show they've tuned in. 