Just a question I thought someone could answer. If you were to wake up during the night, mid sleep cycle, regardless of which stage you were in, if you were to go back to sleep almost instantaneously or even take a few minutes, would you re-enter the cycle where you awoke or would you start the cycle from the beginning.

I was just wondering because if you attempt a WILD LD technique for example which involves waking up during the night, would you have to go through each stage again and REM sleep is towards the end of a sleep cycle which is, in average, 90 minutes long. I've never performed a WILD, but sounds like no-one waits 90 minutes or close to that to perform the technique. So scientifically speaking, what happens?