Charles A. Czeisler is a researcher and author in the field of circadian rhythms and sleep medicine. He holds both an M.D. and a Ph.D. and is currently the Chief and Director of the Division of Sleep Medicine at Harvard Medical School (http://hms.harvard.edu/hms/home.asp) and Brigham and Women's Hospital (http://www.brighamandwomens.org/) in Boston, MA, USA. He has published many scientific articles on how the sleep homeostat interacts with the circadian drive to sleep. He is concerned about safety issues caused by sleep deprivation, particularly reduced job performance among drivers of vehicles and medical professionals.
Selected articles can be found on his webpage: http://sleep.med.harvard.edu/people/faculty/210/Charles+A+Czeisler+PhD+MD+FRCP
A more complete list can be found on Pubmed (search "Czeisler CA" or "Czeisler Circadian"): http://www.ncbi.nlm.nih.gov/sites/entrez