Usually it takes over an hour to reach the inital REM periods, where you dream. If you tried to WILD when going to bed for the first time, you'd have to stay conscious through the deep sleep phases leading up to the first REM period, which isn't easy considering the duration of those phases.

Many people can get into SP from the beginning, but it's much harder to get into a dream from there. Sleeping 5-6 hours first does wonders for WILDing.

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