What are the causes of numbness in just one leg?

If sudden numbness occurs in only one leg, it may be from sitting or standing in one position too long leading to compression of a nerve that runs from your spine to your leg. This is commonly known as "your leg falling asleep" or in medical-speak a "compressive neuropathy". Compression of the nerve can happen at several points as the nerve exits your spine and runs along bone or muscle down the leg. On the other end of the spectrum, one leg falling asleep suddenly may be the result of damage to the brain from a stroke. Typically, other symptoms will be present such as changes in speech, loss of consciousness, headache or vision changes. Lastly, one leg falling asleep may be a very early sign of a systemic diseases of the nerves like multiple sclerosis, vitamin deficiencies or infections. If symptoms persist, worsen or are associated with other alarming symptoms, check your symptoms to help determine when to seek medical attention promptly.