The cause of the disease may be due to excessive activity during the day resulting in damage to the muscles in the thigh area, which produces a buildup of lactic acid in the muscles, which is not metabolized out in time, resulting in soreness in the thighs after waking up. In addition, the muscles in the thigh area are not running smoothly due to prolonged cold when sleeping, and there are stagnant blood stasis and obstructed meridians, which will also have the performance of thigh pain. It may also be due to incorrect sleeping posture, keeping the thighs in one position for a long time, the thighs are compressed, resulting in poor local blood supply, there will be obvious pain in the root of the thighs. There are also pathological factors such as arteries, venous thrombosis or varicose veins in the lower limbs, which can easily cause blood vessel blockage and cause pain in the legs when the blood supply is insufficient.