restless legs syndrome

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A neurological disorder characterized by an uncontrollable urge to move the legs caused by uncomfortable sensations such as aching or crawling. It occurs after going to bed and often leads to insomnia.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A neurological disorder characterized by an irresistible urge to move one's body to stop uncomfortable or odd sensations, usually in the legs.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun feeling of uneasiness and restlessness in the legs after going to bed (sometimes causing insomnia); may be relieved temporarily by walking or moving the legs