This Phase II proposal will perform the validation, testing, and software development for a commercially acceptable Actillume instrument. We will revalidate improved sensor designs, an external photo transducer, and new calibration protocols. A new user-friendly software package will be developed for device initialization, data recovery, data editing, plotting, and statistical analyses. An automated clinical report will be developed. A user procedure manual will be written. Human engineering will be evaluated through use-testing with a variety of research subjects and sleep clinic patients. In addition, to provide preliminary normal ranges for clinical use, 50 subjects will be monitored in San Diego and 50 subjects will be monitored in Rochester, Minnesota in each of the 4 seasons of the year. Consortium agreements with the University of California, San Diego and the Mayo Clinic will support these studies. Phase II will produce an Actillume system for studies of sleep disorders patients, affective disorders, elderly, premenstrual syndrome, shift work, jet lag, the chronically ill, etc. Enthusiasm for the device indicates a substantial market. In Phase III, quantity production will permit lower-cost production.