Circadian RA Study in Rheumatoid Arthritis Subjects

Primary objective: To determine the changes in circadian activity rhythms and disease activity in rheumatoid arthritis (RA) patients from pre-treatment to one month after Enbrel initiation. Secondary objectives: * To determine if there is an association between changes in circadian rhythm and changes in disease activity in active RA after initiation of Enbrel * To determine if the changes in circadian activity rhythms are associated with systemic inflammation in RA patients * To determine changes in traditional sleep quality variables from pre-treatment to one month after Enbrel initiation in RA patients