You know something about the cycles but not enough. I’m not judging here, just trying to point out very important, the most important thing. Learn everything you can about sleep cycles. Use wikipedia.
Long story short you can’t physically dream for 9 hours straight because our brain/body goes through 4 main stages of sleep which one of them is REM sleep in which we dream. It is known that we do dream in NREM cycles too but that is irrelevant because most of the dreams that we do remember are REM dreams.
So once when we cycle through those 4 stages of sleep body goes again through 4 stages of sleep. Of course NREM stages become shorter because you don’t need relaxing and falling asleep any more and REM becomes longer but that means that you dream or to better say you enter REM sleep every 90 - 120 minutes which is also the length of all 4 stages combined together. Those 90 - 120 minutes vary from dreamer to dreamer, they are just the average number.
So after every sleep stage is complete “micro awakenings” occur. So after NREM 1 stage awakening occur and after second and third NREM stage as the REM stage too. So physically you are waking up every now and then so you can’t be asleep for 9 hours and dream for that time. Those micro awakenings occur usually to move and change position and so on. Sometimes when somebody comes to our room we do respond but we don’t remember doing anything when the person tells us that we talked to them, that is usually also happening in micro awakenings or when we are very close to the end of sleep stage in which we are at the moment because the sleep becomes lighter as the stage/cycle is coming to its end.
If you have any questions regarding WILD I will be more then happy to answer!