Cluster headache (CH), also known as "suicide headache," is characterized by a distinctive behavior during attacks. In 80% to 90% of cases, patients are restless and constantly moving in a vain attempt to relieve pain. They often perform complex, stereotyped actions. During attacks, CH sufferers do not want to be touched, stroked, or comforted and frequently moan a great deal, cry, or even scream. They sometimes indulge in violent, self-hurting behavior. Restlessness is a highly sensitive and highly specific parameter for CH and has been included among the signs and symptoms accompanying pain of the disorder in the Second Edition of the International Classification of Headache Disorders. A few hypotheses on pathophysiology of restlessness are addressed in this paper.