Lying down all the time legs feel especially tired, the main reason to consider with poor posture, lower limb blood circulation is not smooth or lumbar spine pathology compression of the nerve root and so on. 1. Poor posture: usually if you keep lying down for a long time, do not take a good posture, leg pressure, may cause local muscle fatigue or circulatory obstruction phenomenon, so it will lead to the symptoms of legs feel particularly tired. 2. Lower extremity blood circulation is not smooth: has been lying down without getting up and activities are likely to affect the body’s blood circulation, when the blood is concentrated in the lower extremities, not a good return, easy to produce the phenomenon of legs feel particularly tired, and even trigger the performance of swelling. 3. Lumbar spine lesions compressed nerve root: long lying down easily lead to muscle strength decline, or even muscle atrophy, affecting the stability of the spine, thus triggering lumbar disc herniation and other lesions, if the compression of the nerve root, it will affect the lower limbs of the motor and sensory functions, resulting in the performance of the legs feel particularly tired. Usually pay attention to appropriate exercise, if the symptoms are more obvious, need to be targeted treatment under the guidance of a professional physician, pay attention to maintain a good posture when lying down.