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In these cases, visual snow is a normal reaction of the body, related to the way photoreceptors (rods) and neurons respond to weak or insufficient stimuli. [ citation needed ] However, if visual snow becomes persistent and continuous — especially if it is accompanied by other symptoms, such as headaches, difficulty focusing, or intense visual ...
Pressure phosphenes can persist briefly after the rubbing stops and the eyes are opened, allowing the phosphenes to be seen on the visual scene. Hermann von Helmholtz and others have published drawings of their pressure phosphenes. One example of a pressure phosphene is demonstrated by gently pressing the side of one's eye and observing a ...
A sensation of falling occurs when the labyrinth or vestibular apparatus, a system of fluid-filled passages in the inner ear, detects changes in acceleration. This sensation can occur when a person begins to fall, which in terms of mechanics amounts to a sudden acceleration increase from zero to roughly 9.81 m/s 2 .
A hypnic jerk, hypnagogic jerk, sleep start, sleep twitch, myoclonic jerk, or night start is a brief and sudden involuntary contraction of the muscles of the body which occurs when a person is beginning to fall asleep, often causing the person to jump and awaken suddenly for a moment.
In animals, including humans, the startle response is a largely unconscious defensive response to sudden or threatening stimuli, such as sudden noise or sharp movement, and is associated with negative affect. [1] Usually the onset of the startle response is a startle reflex reaction.
Cold shock response is a series of neurogenic cardio-respiratory responses caused by sudden immersion in cold water.. In cold water immersions, such as by falling through thin ice, cold shock response is perhaps the most common cause of death. [1]
The statement said the "pulsing sound" has stopped. "The crew is asked to contact mission control when they hear sounds originating in the comm system," NASA said. "The speaker feedback Wilmore ...
The contractions are very rapid, occurring as often as 150 times a minute, and may persist during sleep. The condition usually appears in adults and can last indefinitely. People with palatal myoclonus usually regard it as a minor problem; some complain of an occasional "clicking" sound, a noise made as the soft palate muscles contract.