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.pomyslnaszycie.com/up-in-smoke-thorax-fr-fleece-welding-hoodie-black-black-for-sale/