Why Do We Dream During Naps?!

I am just wondering why people dream during naps? They are usually shorter than normal sleep and are in no way part of a sleep schedule. I understand that sleep cycles take at least 90 mintues to begin and finish and REM sleep becomes longer after hours of sleep. So why do we dream during naps?

P.S. everytime I have had a nap I have come at lot closer to becoming Lucid, i also have very vivd dreams during naps, more so than regular sleep. Any Reason?

Thanks

no stopping the authentic flow of dreams.

When someone learns to dream consciously you may find yourself moving beyond levels of dreams that were previously unknown or previous beyond your comprehension.

the 90 min to REM sleep cycle is sound, but I have been successful to getting lucid in 20 minutes.

I only know this as my experience as several times I would wake up after a 1/2hour nap.

There is left-over REM until.. what is it 9/10 hours? Something like that. And you don't need to be in REM to dream.