Cramps are muscle spasms. Sleeping leg cramps in middle-aged and elderly people may be caused by calcium deficiency, overwork and cold. 1. Calcium deficiency: the middle-aged and the elderly due to gastrointestinal malabsorption function and lead to insufficient calcium absorption, osteoporosis, female estrogen decline caused by a decrease in blood calcium levels, resulting in an increase in muscle stress and spasms. 2. Overexertion: Overexertion can lead to the accumulation of acidic metabolites in the muscles, which consumes calcium ions and lowers the blood calcium level, thus causing spasms of the leg muscles. 3. Cold: the cold stimulation caused by poor local circulation, increased excitability and cause leg muscle spasms. Middle-aged and elderly people who have leg cramps in bed need to go to the hospital as soon as possible for diagnosis, and according to the specific condition of the corresponding conditioning and treatment.