Charles A. Czeisler is a researcher and author in the field of circadian rhythm

Circadian rhythm

A circadian rhythm, popularly referred to as body clock, is an endogenously driven , roughly 24-hour cycle in biochemical, physiological, or behavioural processes. Circadian rhythms have been widely observed in plants, animals, fungi and cyanobacteria...

s and sleep medicine

Sleep medicine

Sleep medicine is a medical specialty or subspecialty devoted to the diagnosis and therapy of sleep disturbances and disorders. From the middle of the 20th century, research has provided increasing knowledge and answered many questions about sleep-wake functioning. The rapidly evolving field has...

. 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