Periodic limb movements of sleep and the restless legs syndrome are not diagnoses but rather an indication that there is some CNS disturbance and are associated with an ever-growing number of conditions. They are very common, exist in many forms and are often overlooked by physicians. It is the author's opinion that they are parts of what has been called an akathisia syndrome in the most severe situations and may include the same mechanisms that underlie attention disorders, chronic fatigue syndrome and "sun-downing." They are likely parts of a syndrome caused by dysfunction in a complex brainstem center. This center's normal function is to maintain a smooth electrical template on which discrete neuronal impulses sculpture the rich repertoire we recognize as sensory and motor function awake and to effect a smooth "switching" mechanism allowing sleep to occur without motor and sensory input invading consciousness (awakening). While the DA-ergic CNS pathways have been thought to be the primary neurotransmitter involved, the opioids secondary, there is mounting evidence that the situation is far more complicated, that many neurotransmitter, including stimulating and inhibiting amino acids, play a part. These patients agonize with their indisposition but can be helped by various treatments. Treatment alleviates not only the distress caused by the symptoms but also the devastating insomnia and excessive daytime sleepiness associated with it.