When you wake up in the morning with leg cramps, there are usually several reasons for this. First, it is due to the legs not paying attention to warmth during the night sleep, out of the skin exposure state or open air conditioning, fans, as well as doors and windows convection. This can cause the skin of the legs and the muscle tissue under the skin to become cold. When you wake up in the morning, the leg muscles are actively contracting, which can easily trigger cramps in the legs. This is because the leg muscles themselves are tighter and the blood circulation is slower when they are cold. Inflammation has a buildup that stimulates the muscle tissue and causes it to become even tighter. Therefore, when there is a slight active contraction of the leg, it induces leg cramps. Second, it is before going to bed, because the legs have had strenuous exercise resulting in more local lactic acid and inflammatory products accumulation. It reaches a relatively high level in the morning when waking up. Therefore, when performing light activities, it is easy to induce leg cramps to appear. Third, there is a possibility of hypocalcemia. It is best to go to the hospital for a blood test to see if the calcium ion is low. This is because low blood calcium is also prone to induce leg cramps.