I’ve noticed that when I sleep in, longer than 7-8 hours, I start dreaming very heavily. I know that I am dreaming all night long, but I don’t remember any of them on an average night. But when I sleep longer than usual, I start having <remembering> seriously long, ongoing, colourful dreams that make it very hard to wake up. That is, I may rise to semi-consciousness but all I want to do is roll over and go back to them. They aren’t necessarily super-pleasant or anything, just so very engaging that reality doesn’t seem very real in comparison, and I just cannot seem to get out of them.
It’s to the point that on weekends I have my sweetie wake me up at specific times, NOT too long, before I start going off into dream-land, because otherwise I end up doing things like, oh, sleeping 14 hours straight and then STILL wanting to just go back to bed and to dreaming.
I’ve always wondered what causes this on a physical level, 'cause lord knows it’s hard for me to ever GET to sleep. It’s like once I’m there, I just can’t bear to give it up! 
Does this happen to anyone else, or know what is going on? It’s purely curiosity, 'cause it does seem kind of weird to me. On workdays, I have no problems getting up in the morning with the alarm; I’m bright-eyed and bushy-tailed. I don’t do anything differently on the weekends regarding going to sleep, no booze or anything. I’m just wondering why the longer I sleep the more intense the dreams become.