Enrollment: All persons presenting for evaluation at the CPC who meet study criteria will be offered the option to participate in the study. Approximately 60 new pain patients are evaluated by psychology monthly and we expect to obtain our goal of 40 participants within 6 months. Informed consent will be obtained in compliance with OHSU Institutional Review Board protocol. Subjects will receive $100 gift certificate compensation, even if they fail to complete the study. We anticipate a low completion failure rate as the study is completed in one 3-hour time block. Study times will be standardized to account for circadian effects. Participants will be told to arrive having eaten a light breakfast with minimal caffeine consumption (e.g., less than 2 cups of coffee). They will be given a subject number and their psychiatric diagnoses will be blinded to prevent bias. The study involves gathering 5 serum samples and thus participants will be catheterized by nursing staff to minimize physiological stress.