Why do you feel that you fall from above while you sleep?

You ever wake up short because you feel that you fall from the bed or from a tall building?
If yes, surely wondering what’s causing this weird feeling.
The phenomenon is called υπναγωγικός spasm –known and no myoclonic jerk– and describes the involuntary contractions of the muscles in the hands, feet or whole body. The υπναγωγικός spasm occurs the moment we fall asleep.
According to the National Sleep Foundation of the united states, the causes of the phenomenon are not clear, but there are a few “popular” theories. One theory is that the spasms result from the slowing down of the operation of the nervous system the moment αποκοιμιόμαστε: As the breathing rate, the heart rate and body temperature fall, altered muscle tone, and this change triggers the convulsive spasms. Another theory is that while αποκοιμιόμαστε, the brain “interprets” the wrong way the relaxation of the muscles as a signal that indeed we so instruct the muscles to tighten abruptly.
As stated in the onmed.gr, the υπναγωγικός spasm is not an indication of a health problem, so you don’t need to worry about if it happens often. It is worth noting, however, that the increased intake of caffeine, vigorous physical activity in the evening, the emotional stress and lack of sleep are associated with greater frequency of seizures. If the spasms you prevent to enjoy a relaxing and αποκαταστατικό sleep, consult your doctor.