How do odd sleeping patterns affect dreaming?

I was just wondering if anyone here knows how strange sleeping patterns can alter the amount of time/quality of dreaming. I know that if you sleep for a very long time in one go, the REM periods get progressively longer. However, what happens when you are only sleeping for a few hours at a time, but at different times throughout the day, so that you're still getting the usual amount of sleep, but interrupted by long periods of wakefulness? Would be interested to know what effect this has on the amount of time spent in REM...

: )

I'd guess that after being awake for a few hours, you reset your sleep cycle, and have to start over with the REM periods.

First, you'll get relatively little REM-sleep (and as such, you'll dream less), since you'll be missing out on the longer REM periods that you normally experience after about 6 hours of sleep.
If you keep up this pattern, however, you'll get REM rebound to prevent a shortage of REM sleep. This means you'll enter REM sleep sooner than normal and a bigger part of of your sleep period will consist of it.
By doing this, people may optimize their time spent awake, by sleeping for short periods of time (less than half an hour) that consist more or less completely of REM-sleep, so they only have to sleep for about 5 hours in a 24 hour period. This is called polyphasic sleeping.