Hypnic Jerks Are Harmless Muscle Spasms During Sleep, Doctor Explains

Dr. Amir Khan, a physician who appears on British television, explained the sudden falling sensation many people feel just as they drift off to sleep. He said the event, known as a hypnic jerk or hypnagogic spasm, is a brief, involuntary muscle contraction that occurs when the brain misinterprets the relaxation of muscles as a loss of balance. The reflex, which may be triggered by stress, caffeine, or fatigue, awakens the sleeper but is otherwise harmless. Studies estimate that up to 70 % of adults experience it at least once in their lives. Dr. Khan reassured viewers that the phenomenon does not indicate a medical problem and requires no treatment.