When you are sleeping your body continues to hit REM periods throughout the whole night. Towards the end of your sleep period, the REM cycles are longer and much closer together. Your body gets into this sleeping pattern during the night and it attempts to continue this even after you awake. Of course you are awake so you aren't getting REM sleep. Throughout the early part of the day your body continues the pattern. It attempts to enter REM, so if you nap attempt to nap during this time, your body will succeed in entering REM sleep. As the day wears on the body gets used to missing the REM cycle and it starts to make attempts further and further apart. That is why the REM cycle at the beginning of a nights sleep is much further apart then during naps and toward the end of a sleep cycle. Generally, try to nap 1-6 hours after waking for best results with nap WILDing. Remember, it is possible to WILD at the beginning of sleep, but it can take hours to accomplish it. Good luck and I hope I helped.