1. Introduction to circadian rhythms Laura K. Fonken and Randy J. Nelson; 2. Central clock dynamics: daily timekeeping, photic processing, and photoperiodic encoding by the suprachiasmatic nucleus Deborah A. M. Joye, Robert Wheeler and Jennifer A. Evans; 3. Melatonin, light, and the circadian system Margarita L. Dubocovich; 4. Disrupted circadian rhythms, stress, and allostatic load Ilia N. Karatsoreos; 5. Disrupted circadian rhythms and mental health Anthony Rosenthal and Tara A. LeGates; 6. Circadian rhythms and cognitive functioning Jacob S. Moeller and Lance J. Kriegsfeld; 7. Circadian rhythm disruption in aging and Alzheimer's disease Marilyn J. Duncan; 8. Circadian rhythms regulate neuroinflammation after traumatic brain injury and spinal cord injury Andrew D. Gaudet and Emily K. Greenough; 9. Disrupted circadian rhythms and neuroendocrine function in fertility Alexandra M. Yaw, Brooke M. DeVries and Hanne M. Hoffmann; 10. Disrupted circadian rhythms and metabolic function Deanna M. Arble; 11. Disrupted circadian rhythms, time restricted feeding, and blood pressure regulation Zhenheng Guo, Tianfei Hou and Ming C. Gong; 12. Disrupted circadian rhythms and immune function Louise M. Ince, Devin Simpkins and Julie E. Gibbs; 13. Circadian rhythms and cardiac function Leandro C. Brito, Saurabh S. Thosar, and Matthew P. Butler; 14. Disrupted circadian rhythms and cancer Baharan Fekry and Kristin Eckel-Mahan; 15. Light effects across species in nature: a focus on solutions Kevin J. Gaston and Johanna H. Meijer; 16. Measurement and analysis of exposure to light at night in epidemiology Xiaozhe Yin and Travis Longcore.