I'm not so sure this is accurate. Speaking entirely anecdotally here, as I haven't done a lot of research on sleep trends. But ever since I saw Inception, I got into lucid dreaming. I only got lucid a handful of times over the years, but in trying to do so I changed my sleeping habits. I get about six hours of sleep every day, but I'm at a point where I fall into REM the minute I'm out. It's supposed to take an hour to fall into the cycle, but I've had cat naps that last about fifteen minutes with a full on dream. Since REM is the part of the cycle where your body rests the most, I feel that if I fall into the cycle sooner rather than later, I can safely shave a few hours off my sleeping time. Just my $.02