The characteristic jerk when falling asleep

Oh Grand Mattster: Why is it that right as I’m falling asleep and beginning some sort of dream sequence, then — BOOM — in my dream I trip or fall or get hit by a bus, causing my body to respond by jerking spastically, which wakes me up? This never happens when I’m in a deep sleep, however I can sometimes be a spastic jerk when fully awake. — Randy Venier, Encinitas

Veeeery interesting, Randy. Come into the Alice Institute for Dream Analysis and Advanced Spackle Technology and curl up on the couch while we poke through your psyche. That just-falling-asleep, surfing-the-alpha-waves time is an odd blend of sleep and waking. Dream content and body sensations still interact to some extent. This is unlike dreams experienced in REM sleep, when motor neurons fire but are normally blocked from activating our muscles (except in sleepwalking). Dream research is tricky stuff, but speculation is that either an external stimulus or intense dream image can wake us more easily in the first stages of sleep, and in response we suddenly reestablish full brain-body connection with that characteristic jerk. And with your high klutz quotient and talent as a good bus target, it’s a good thing dreamers very rarely experience physical pain related to dream content.