Hello, Your legs often feel numb and you have a tendency to fall, you had also passed out for many hours sometime back. There are many factors and medical conditions that may cause numbness in the legs. 1. It may be due to compression of the blood flow that is caused by inflammation, trauma, disease, or infection 2. Leg numbness experienced after continued sitting or standing is due to nerve compression or due to nerve damage from health conditions such as multiple sclerosis 3. Numbness or paresthesia may also cause tingling, prickling, or a burning sensation is also a possibility 4. Numbness can also be caused due to circulatory conditions such as deep vein thrombosis, frostbite, arteriovenous malformation, or peripheral artery disease 5. Numbness can also be caused by osteoporosis and orthopedic causes like a back injury, herniated disk, degenerative disk disease, and nerve entrapment, etc. 6. Neurological diseases like alcohol leg, hypothyroidism, diabetic neuropathy, lead poisoning, stroke or tumor etc., may also cause numbness of the legs 7.The nerves may be affected by a deficiency in vitamin B12 and inflammation within the spinal cord. You are suggested to get clinically examined by a neurologist and GP, get all required tests and investigations done. The pathology detected to be causing you symptoms will be treated at the earliest. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician