What that means is that it is healthy to go to bed as early as possible so you can get lot's of REM sleep. For example, the reason you dream when you nap in the afternoon for a short time is because when you take a nap later in the day your body goes into REM much faster for some reason. So the more early you go to bed, the faster you get into REM, which means more REM when you sleep at night, which means more Lucid Dreaming.

So basicly what I'm saying is you should try to go to bed early.