Robert Leroy Sack (born March 14, 1942) is an American physician and researcher specializing in sleep medicine.
On the faculty of the Oregon Health & Science University since 1977, he is the medical director of its Clinical Sleep Disorders Medicine Program which he developed parallel with his research on circadian rhythms.
[1] For many years, Sack, together with Alfred J. Lewy, has conducted research on sleep, light therapy and melatonin.
[2] Dr. Sack is, as of February 2010, listed as author of 71 PubMed articles, of which 17 are reviews.
[3] His discovery of the power of the hormone melatonin to entrain people with circadian rhythm sleep disorders has benefited many people, both blind and sighted,[4][5] earning him credit in a New England Journal of Medicine editorial.