A hypnic jerk is an abrupt. involuntary. nonrepetitive contraction of muscles of the body that occurs during the onset of sleep in stage 1 of nonrapid eye movement sleep. Various physiological and stressful stimuli can precipitate hypnic jerks with no further neurological sequelae. https://www.lightemupsequences.com/limited-save-Custom-Congratulations-Banner-p4839-hot-choice/