Feeling cold below the knees at night may be caused by vascular diseases of the lower limbs, lumbar diseases, osteoarthritis and other conditions. 1. Lower limb vascular diseases: the cause may be due to the long-term stagnation of venous blood or the occlusion of arterial blood vessels. For example, in varicose veins of the lower limbs, a large amount of venous blood is stagnated and the blood circulation is obstructed, which results in pain, swelling and coldness of the lower limbs. When arterial occlusive vasculitis of the lower limbs occurs, arterial blood decreases, causing ischemia and hypoxia of the limbs, which can also lead to coldness of the lower limbs. 2. Lumbar diseases, osteoarthritis: lumbar diseases causing coldness below the knee is due to sensory impairment caused by compressed nerves, such as lumbar intervertebral disc herniation, spinal stenosis and other diseases, which can lead to coldness in the area of self-sensory nerves innervated by the patient. Osteoarthritis patients feel cold may be due to joint degeneration caused by blood flow around the joints. For example, osteoarthritis of the knee and synovitis. There may be other reasons why you feel cold below your knees at night, so it is recommended that you go to the hospital in time, complete the examination to clarify the cause of the disease, and then give targeted treatment or therapy under the guidance of the doctor.