if i sleep longer,will i have more dreams??
Appended “(Question about sleeping longer)” to topic title for clarification. 
Your deepest sleep with REM, is in the morning before you wake up. So it would seem you if slept longer you would indeed have more dreams.
Excess sleep usually consists of REM. Therefore, if you are not tired, but yet you sleep, you will probably be dreaming a lot.
I’ve found that when I do I generally have more dreams, but then people tend to use ‘have’ and ‘remember’ interchangeably whether or not they know it. I ‘remember’ dreams more when I sleep longer usually because I awake once or twice (to turn the alarm off) and go back to sleep (for thirty minutes, yeah right… 
).
What happens is that I have unintentionally performed a WBTB at the most opportune moment: my mind is fairly awake, and the time just happens to be when REM is the longest.
Sadly, I tend to go in and out of sleep during these times and any memory of dreams is usually torn up by the repeated WBTB. Sometimes it survives, but usually not often.
In conclusion, sleeping later can help you recall more dreams, and obviously lets you have more as you’re sleeping for longer. The only problem is the possible downside of loss of recall. Anywho I wish you luck if you try extending your sleep cycle!
Sleeping longer will yield more dreams. Though as xaos and paulius have pointed out the extra rem sleep is light and you wake up more. For some dreamers the “natural” wbtb could be detrimental to dream recall. But for some it may not.