Multi-scale Modeling of Sleep Behaviors in Social Networks

College undergraduates are studied in cohorts of ~ 50 in fall or spring semesters. They complete diaries once in the morning and once in the evening about sleep/wake timing, timing of social and school activities, and mood. They wear physiological sensors. They install (1) an application on their mobile phone that tracks timing, duration and de-identified sender/recipient of phone calls and text messages, use of internet or apps (but not the content or names of those internet sites and apps) and (2) meal content and timing. They also spend at least one overnight session providing saliva samples for later assay for hormones.