Physically, hypnic jerks resemble the "jump" experienced by a person when startled, sometimes accompanied by a falling sensation.[1] Hypnic jerks are associated with a rapid heartbeat, quickened breathing, sweat, and sometimes "a peculiar sensory feeling of 'shock' or 'falling into the void'".[2] It can also be accompanied by a vivid dream experience or hallucination.[3] A higher occurrence is reported in people with irregular sleep schedules.[4] Moreover, when particularly frequent and severe, hypnic jerks have been reported as a cause of sleep-onset insomnia.[3]
https://en.wikipedia.org/wiki/Hypnic_jerk
This I have experienced many times while asleep!
#hypnicjerk #hypnictwitch