The feeling of falling from a height in sleep, clinically known as muscle jerk, is a relatively common physiological phenomenon, the possible causes include; 1, too intense exertion during the daytime activities, or muscle tension for a long time, coupled with mental state fatigue, after sleep due to the brain’s unclear judgment of the human body’s activity state, caused by a stress response of the whole body muscle contraction. It is the protection of the muscle itself that produces the muscle twitching phenomenon after sleep. 2, simply due to the lack of calcium in the muscle, or too high concentration of calcium ions, resulting in muscle spasms, which produce involuntary twitching after sleep. 3, such as patients who have had traumatic brain injury or brain hypoxia, may also produce muscle twitching or other sequelae, patients with epilepsy may also have muscle twitching symptoms. These types of conditions are manifested in dreams as the phenomenon of falling from height. If you have symptoms of muscle twitching for a long time, you can take some psychotropic drugs such as clonazepam.