Ever since christmas, santa has been plagued by the constant worry that he has forgotten to deliver some of his presents. he finds that the only way to get this thought out of his head is to periodically check his sleigh for undelivered presents. santa's worried thoughts are called and his checking behaviors are called

obsessions  
compulsive rituals    
Santa seems to have obsessive compulsive disorder. This is an anxiety disorder where the victim experiences undesired or repetitive thoughts that cause anxiety that's only revealed by engaging in a obsessive behavior. Performing this action provides only temporary relief, until the undesired thoughts or impulses reoccur.