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I went through a period of waking up at 3 a.m . most nights and it felt nearly impossible to fall asleep again. I tried everything from breath techniques designed to calm my nervous system, to getting out of bed and 'pottering' in another room, but nothing worked.

After repeated 3 a.m. wake-ups that were draining me of energy the next day, I decided to get to the bottom of not only why I was waking up at 3.a.m, but how to fall asleep fast again in the middle of the night.

Key take-aways: At a glance

The 3 a.m. wake-up fix: Cognitive shuffling is a mental exercise designed by cognitive scientist Dr. Luc P.…