Many people suddenly feel their feet stepping on the air when they sleep, which is a normal phenomenon. Because people sleep from light sleep to deep sleep, the cerebral cortex will be inhibited during the process of sleep. However, some of the cerebral cortex may have functional activity, so it will lead to muscle contraction, making patients feel their feet step on the air or have muscle twitching when they sleep. This condition is related to the patient’s usual overwork and mental tension, so the patient should not be too nervous. If the patient often happens to have sudden foot stepping when sleeping, it is recommended that the patient check whether it is caused by calcium deficiency and other reasons, and can check the serum ion to see the level of blood calcium. Patients should avoid catching cold, because when the lower limbs are cold also easily lead to patients with leg cramps.