My legs and feet often go numb. mostly when i'm lying down, but it happens when i am standing for long periods of time as well. what could this be?

Nerve impingement: There are a number of potential causes for what you describe, but your symptoms are quite possibly due to nerve impingement. In order to find the appropriate treatment, you should speak to a doctor thoroughly about your symptoms, have a physical exam done, and possibly MRI, and they can work on a treatment plan with you. Best wishes.

Nerve abnormality: It could be due to an abnormality in the spinal cord (disc pushing on the spinal cord) or a process in the nerves of the legs causing problems (diabetes, for example). It is not normal and should be checked by neurologist.