Suddenly feeling down while sleeping is the occurrence of prodromal sleep myalgias, also known as myalgias. It is not a disease and occurs in 70% of the normal population. The cause of this condition is often related to overexertion or incorrect sleeping posture, as well as calcium deficiency. This condition often occurs when the patient has just fallen asleep or is about to wake up, when the patient’s higher nerve functions are in a state of inhibition and the inhibition of the lower centers is lost, causing the lower centers to become overactive when they receive minor stimulation, causing muscle contractions. Patients often experience a falling sensation or shaking of the limbs during sleep, which wakes them up and does not require special treatment. If the attacks are too frequent, the presence of anxiety needs to be clarified.