@kaliswaran392: Have you ever suddenly felt as though you were falling from a great height just as you were drifting off to sleep? That unexpected body jerk is known as sleep myoclonus or a hypnic jerk. It is a common, harmless physiological phenomenon that occurs during the transition from wakefulness to Stage N1 non-rapid eye movement (NREM) sleep. Although the exact neurophysiological mechanism remains incompletely understood, factors such as sleep deprivation, psychological stress, anxiety, excessive caffeine or nicotine consumption, stimulant medications, and vigorous exercise close to bedtime may increase its frequency. An interesting evolutionary hypothesis suggests that hypnic jerks may represent a remnant of an ancient protective reflex that briefly aroused our ancestors before they entered sleep in potentially hazardous environments. #sleeptwitching