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Portrait of Michael Rosbash
Photo: John Sears, Own work · CC BY-SA 4.0 via Wikimedia Commons

Nobel Prize in Physiology or Medicine · 2017

Michael Rosbash

The son of refugees from Nazi Germany, he helped show how genes in our cells build the 24-hour clock that times sleep and waking.

The Nobel citation: “for their discoveries of molecular mechanisms controlling the circadian rhythm”
Born
March 7, 1944, Kansas City, MO, USA
Shared with
Jeffrey C. Hall, Michael W. Young
Affiliation at the time
Brandeis University, USA; Howard Hughes Medical Institute, USA

Medicine prize

2017

Shared with 2 other laureates.

Age that year

73years

Born in 1944.

Sources cited

21

Fact-checked September 24, 2026.

  • The morning after Kristallnacht, the Gestapo came to his grandmother's home looking for his father. She told them they were too late: he had gone to America.
  • At his 1965 Caltech graduation, the dean told him he had entered with the lowest predicted grades in his class, and had done far better than predicted.
  • He spent $50,000 of his 1989 start-up grant on fly activity monitors built by a small local firm. Labs worldwide still use them; he never made money from them.
  • When the Nobel call woke him at home, he was so stunned he could barely breathe. His wife told him to start breathing.
  • He had a heart attack at 38, the kind of illness that killed his father at 42.

The breakthrough

Finding the feedback loop that keeps the body's daily clock ticking

Almost every living thing runs on an inner clock of about 24 hours. It tells the body when to sleep, wake, release hormones and digest food. For centuries nobody knew how that clock worked inside cells. In 1971 Ronald Konopka and Seymour Benzer found fruit flies with broken clocks and traced the fault to one gene, which they named period. In 1984 Rosbash and his Brandeis colleague Jeffrey Hall, racing Michael Young's team in New York, isolated the gene and showed that adding a healthy copy to clockless flies brought their daily rhythm back. Rosbash's lab brought know-how in RNA, the working copies that genes make of themselves. In 1990 his team showed that the amount of period RNA in fly heads rises and falls every 24 hours, and that the gene's own protein, PER, drives the cycle. They proposed a loop: the gene makes PER, PER builds up overnight, enters the cell's nucleus and switches its own gene off, then breaks down so the cycle can start again. It works like a thermostat that turns the heater off once the room is warm and back on as it cools, except each loop takes about a day. In 1998 Rosbash and Hall's groups identified the fly genes for the proteins that switch period on, and showed that a protein called cryptochrome is a main light sensor that lets daylight reset the fly's clock.[3],[4],[5],[12],[13],[14],[15]

“I am just a regular guy, a scientist who got incredibly lucky.”
Michael Rosbash, Closing words of his Nobel lecture, "Circadian Rhythms and the Transcriptional Feedback Loop," Stockholm, 7 December 2017.[3]

What it meant for humanity

The clock Rosbash helped take apart runs in people too. The same kind of loop, built from close relatives of the fly genes, keeps time in human cells, and the Nobel Assembly noted that a large share of our genes are regulated by it. The clock helps set sleep, hormone levels, body temperature, blood pressure and metabolism. That knowledge changed how scientists think about sleep, jet lag and night work. Jet lag, for example, is a mismatch between the inner clock and local daylight. The work also helped researchers find genetic causes of some sleep disorders. In 2001 a US team found that people with an inherited condition that makes them extreme "morning larks," sleeping about four hours early, carry a mutation in PER2, a human version of the fly period gene. Understanding the clock matters for the roughly one in five workers worldwide who work regular night shifts. The World Health Organization's cancer agency classifies night shift work as probably carcinogenic, and the Nobel committee noted possible links between chronic clock disruption and cancer, metabolic disorders and inflammation. Scientists are now studying whether the timing of meals matters and looking for drugs that adjust the clock. Rosbash is candid that the payoff so far is mostly understanding. In his Nobel lecture he said the prize honored physiology more than medicine and that major medical uses remain a future goal, though he is optimistic because so much of the body runs on the clock. He also helped build the field's tools: fly activity monitors he paid a small Waltham company to develop in 1989 are still sold and used in labs around the world.

  • The Nobel Assembly said the laureates' work explains how plants, animals and humans keep their biological rhythms in step with Earth's rotation, and that the same clock principles operate in human cells.[4],[5]
  • In 2001 researchers found that people with an inherited form of extreme "morning lark" sleep, about four hours early, carry a mutation in hPER2, a human version of the fly period gene that Rosbash and Hall helped isolate.[4],[16]
  • The WHO's cancer agency estimates that about one in five workers worldwide works regular night shifts and classifies night shift work as probably carcinogenic to humans.[17],[18]
  • A PubMed search in September 2026 returned more than 118,000 records mentioning "circadian," about 5,400 of them from 2025 alone. The Nobel Assembly called circadian biology a vast and highly dynamic field.[4],[19]
  • Fly activity monitors that he paid a small Waltham robotics firm to develop in 1989 are still sold and used by labs around the world. He says neither he nor his lab ever received money from the company.[3]

Impact in numbers

Rosbash's contribution is understanding, not a product. With Jeffrey Hall and Michael Young, he showed that a biological clock is built from genes and proteins that switch one another on and off in a daily loop, a principle that also holds in human cells. That insight turned the study of daily rhythms into a molecular science. It underpins current research on inherited sleep disorders, jet lag, the health effects of night work, meal timing and possible drugs that adjust the clock. We make no quantified claim. Rosbash said in his Nobel lecture that major medical applications remain a future goal, and no published estimate links this work to a number of lives saved, patients treated or dollars earned. Any such figure would rest on assumptions we cannot document. Credit is also widely shared: Konopka and Benzer found the period gene, Young's lab found timeless and doubletime, and Joseph Takahashi's lab led the parallel work in mammals.

Fundamental scienceHealth

No number is given here on purpose. Some contributions cannot be counted honestly, and we would rather describe them than invent a figure.

The double edge

No harm from Rosbash's work is documented. It is basic biology done mostly in fruit flies, and its medical payoff is still largely ahead. The controversies are about how the science was done and who got credit. In his Nobel lecture Rosbash admitted that racing Michael Young's lab, and a lack of caution, led him to publish a 1986 paper claiming the PER protein was a proteoglycan, a type of sugar-coated protein, based on evidence he later judged too superficial. A 1987 paper from Young's lab and a collaborator supported a related idea; it was retracted in 1992 after a technician from Hall's lab, working in a Harvard lab, and a Woods Hole team that included one of the paper's own senior authors could not repeat its key experiments. Credit is also shared unevenly. Ronald Konopka, who co-discovered the period gene with Seymour Benzer in 1971, died in 2015, two years before the prize.

  • Minor

    A wrong turn during a fierce rivalry

    Rosbash says competition with Young's lab pushed him to publish a 1986 claim that PER is a proteoglycan on weak evidence, a mistake he takes full responsibility for. A related 1987 Nature paper from Young's lab and David Spray's lab was retracted in December 1992 after repeat attempts, one by Hall's lab and one at Woods Hole involving Spray himself, failed to reproduce its key experiments.[3]

  • Minor

    The gene's discoverer was not there to share the prize

    Ronald Konopka designed and ran the 1971 fly screen with Seymour Benzer that found the period gene, the starting point for the prize-winning work. He died in 2015, two years before the prize was awarded.[3],[4],[20]

Against the odds

Rosbash was born in Kansas City in 1944 because Nazi Germany had driven his parents out. Both were university students, his father in law and his mother in medicine, until Jews were shut out of those paths around 1933, when new laws capped "non-Aryan" university admissions and pushed Jews out of medicine and law. His father became a cantor and in 1937 took a post at a synagogue in Breslau. His mother insisted on leaving, and they reached the United States in 1938, a few months before Kristallnacht. The morning after that pogrom, the Gestapo came to his grandmother's home in Baden-Baden for his father. That day, Jewish men arrested in Baden-Baden were marched through town and held for deportation to Dachau, among about 26,000 Jewish men sent to concentration camps. In New York his mother cleaned hotel rooms while his father searched for work, until a Reform congregation in Kansas City hired him. His mother's family went to Brazil, and she saw her parents only once more. After his father died in 1954, she gave up a place at medical school to support her two sons. Rosbash himself grew up in Newton, Massachusetts, and no source we found records antisemitism aimed at him. He built his career at Brandeis, which the American Jewish community founded in 1948, when Jews and other minorities faced discrimination in higher education.

  • 1933

    Discrimination

    His father was studying law and his mother medicine in Germany until Jews were barred from those professions, around 1933 by his account. That April, Nazi laws capped "non-Aryan" university admissions at 1.5 percent and sharply curtailed Jewish work in medicine and law.[2],[9]

  • 1938

    Exile

    His parents fled Nazi Germany for the United States in 1938. His father loved Germany and did not want to go; his mother said she would leave with or without him. Her own parents and brothers went to Brazil, and she saw her parents only once more before they died.[1],[2]

  • 1938

    Persecution

    The morning after Kristallnacht, the Gestapo came to his grandmother's home in Baden-Baden demanding his father, who had already left. That day, Jewish men arrested in the town were marched through the streets and held for deportation to Dachau.[2],[10]

  • 1938

    Poverty

    His parents arrived in New York with few resources and no job. His mother cleaned hotel rooms while his father joined many refugee rabbis and cantors looking for work, until a Kansas City Reform congregation hired him.[2]

  • 1954

    Other

    His father died of a heart attack at 42. His mother, who had been admitted to Boston University's medical school, had to give up her dream of becoming a doctor and go to work to support her sons.[2]

Jewish background

Both parents JewishIdentified as Jewish, secular

Both parents were German Jews who fled Nazi Germany in 1938. His father, Alfred, came from a religious, kosher Baden-Baden family whose roots were in Kremenchuk, Ukraine, and worked as a cantor in Breslau, Kansas City and Boston. His mother, Hilda, came from a secular Berlin family. His father died in the synagogue on the eve of Yom Kippur in 1954, soon after chanting Kol Nidre. Rosbash describes himself as an atheist who is strongly against religion, yet writes of a deep emotional tie to this family history and jokes about his Jewish guilt. Jewish reference lists include him.[1],[2],[7],[8]

Key dates

  1. 1938

    His parents, German Jews barred from their university studies, flee Nazi Germany for the United States months before Kristallnacht.[1],[2]

  2. March 7, 1944

    Born in Kansas City, Missouri, where his father is the cantor of a Reform congregation.[1],[2]

  3. 1954

    His father dies in the synagogue on the eve of Yom Kippur, aged 42, leaving his mother to raise two boys alone.[2]

  4. 1965

    Graduates from Caltech in chemistry and spends a year in Paris on a Fulbright scholarship.[2],[7]

  5. 1970

    Earns his doctorate at MIT, then spends three years as a postdoctoral fellow in Scotland, mainly at the University of Edinburgh.[1],[2],[7]

  6. 1974

    Joins Brandeis University, founded by the American Jewish community in 1948, and stays there for the rest of his career.[1],[2],[11]

  7. 1982

    Starts a collaboration with Jeffrey Hall to clone a fruit-fly clock gene, the project that led to his Nobel Prize.[3]

  8. 1984

    With Hall, isolates the period gene and shows that a healthy copy restores daily rhythms in arrhythmic flies.[4],[13]

  9. July 1, 1989

    Becomes a Howard Hughes Medical Institute investigator.[3],[21]

  10. February 8, 1990

    Publishes the feedback-loop paper in Nature: the PER protein makes its own gene's RNA rise and fall on a daily cycle.[3],[12]

  11. 1998

    His lab and Hall's identify the fly Clock and cycle genes that switch period on, and show that cryptochrome is a main light sensor for the fly clock.[3],[14],[15]

  12. October 2, 2017

    Shares the Nobel Prize in Physiology or Medicine with Jeffrey C. Hall and Michael W. Young. The call wakes him at home.[1],[4],[6]

Sources

  1. 1.Michael Rosbash - Facts · NobelPrize.org (Nobel Prize Outreach), 2017
  2. 2.Michael Rosbash - Biographical · NobelPrize.org (Nobel Foundation), 2017
  3. 3.Circadian Rhythms and the Transcriptional Feedback Loop (Nobel Lecture, 7 December 2017) · NobelPrize.org (Nobel Foundation), 2017
  4. 4.The Nobel Prize in Physiology or Medicine 2017 - Press release · The Nobel Assembly at Karolinska Institutet, 2017
  5. 5.The Nobel Prize in Physiology or Medicine 2017 - Advanced information (scientific background) · The Nobel Assembly at Karolinska Institutet, 2017
  6. 6.Michael Rosbash - Interview (including telephone interview, 2 October 2017) · NobelPrize.org (Nobel Prize Outreach), 2017
  7. 7.Michael Rosbash · Wikipedia
  8. 8.Jewish Nobel Prize Winners in Physiology or Medicine · JINFO.ORG
  9. 9.Anti-Jewish Legislation in Prewar Germany · United States Holocaust Memorial Museum (Holocaust Encyclopedia)
  10. 10.Kristallnacht · United States Holocaust Memorial Museum (Holocaust Encyclopedia)
  11. 11.Our Story · Brandeis University
  12. 12.Feedback of the Drosophila period gene product on circadian cycling of its messenger RNA levels (Hardin, Hall & Rosbash, Nature 343:536-540) · Nature, via PubMed, 1990
  13. 13.P-element transformation with period locus DNA restores rhythmicity to mutant, arrhythmic Drosophila melanogaster (Zehring et al., Cell 39:369-376) · Cell, via PubMed, 1984
  14. 14.A mutant Drosophila homolog of mammalian Clock disrupts circadian rhythms and transcription of period and timeless (Allada et al., Cell 93:791-804) · Cell, via PubMed, 1998
  15. 15.CRY, a Drosophila clock and light-regulated cryptochrome, is a major contributor to circadian rhythm resetting and photosensitivity (Emery et al., Cell 95:669-679) · Cell, via PubMed, 1998
  16. 16.An hPer2 phosphorylation site mutation in familial advanced sleep phase syndrome (Toh et al., Science 291:1040-1043) · Science, via PubMed, 2001
  17. 17.Night Shift Work (IARC Monographs on the Identification of Carcinogenic Hazards to Humans, Volume 124) · International Agency for Research on Cancer (WHO), 2020
  18. 18.IARC Monographs Volume 124: Night Shift Work · International Agency for Research on Cancer (WHO), 2020
  19. 19.PubMed search: circadian (118,677 results; 5,419 from 2025; 24 September 2026) · US National Library of Medicine, 2026
  20. 20.Ronald J. Konopka (1947-2015) (Rosbash, Cell 161:187-188) · Cell, via PubMed, 2015
  21. 21.Michael Rosbash, PhD · Howard Hughes Medical Institute

Fact-checked on September 24, 2026 by a separate AI fact-checking pass that re-opened the sources, with 5 corrections made. How we check

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