Foot cramps are caused by a variety of reasons: first, long time to keep a sleep position, usually sleep, if long time to keep a sleep position, such as long time lying on the back or prone, these positions will lead to a muscle in the calf for a long time to keep a state of absolute relaxation. This muscle condition will be in a passive spasm, so the foot cramps. Second, the body of estrogen decline, with the increasing years, especially the elderly women, estrogen levels continue to decline, osteoporosis in the body, the body of blood calcium levels will be lower than the average, the stress in the muscle increases, it will cause muscle spasm, always cramps. Third, by the external cold stimulation, if the external environment is too cold, the muscles in the body will be cold stimulation, for example, in the cold winter, the indoor temperature is relatively low, this time if you do not pay attention to keep warm or cover the quilt is relatively thin, the body is very easy to appear foot cramps. Fourth, insufficient rest or too much rest, we find excessive fatigue sleep time is not enough, or usually sleep too long, can cause the body localized acidic metabolite accumulation, it can stimulate muscle spasm.