Additional Study Information: We are currently looking for healthy, nonsmokers, ages 18-49yrs who are satisfied with their sleep to participate in a sleep study. Participants should typically sleep 7-9 hours/night without external sleep aids. Participants must be willing to change their sleep schedule for approximately 4 weeks. Compensation of up to $1000 will be provided for completing all study measurements. In addition, you must be willing to come to Columbia University Irving Medical Center for a baseline visit and once every week for the duration of the study. For more information and to see if you may be eligible, please e-mail: Lrn2116@cumc.columbia.edu or gdm2130@cumc.columbia.edu.