Most WILDers tend to wake up later in the middle of their sleep (say 4 hours in). This is known as WBTB (Wake Back To Bed).

They do this because when you wake up in the middle of your sleep, you have a chance of being in REM sleep. Dreams occur in REM and REM periods come later in your sleep cycle. Some have said that they have WILDed in N-REM (Without any previous sleep) with success, although WILDing while you're in REM is much easier.