How long do I have to keep thinking about staying in the backyard for? Is it till I dream, or just for a few minutes while still awake. It will get very tedious otherwise.
for me it takes less than a minute.
However if you feel really awake during the brief awakening it might not work, also if your really tired during the brief awakening than it might not work.
The key is to be a balance not to tired, but not too awake.
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