Circadian Rhythm Researchers Win Nobel Prize
The Royal Swedish Academy of Sciences has awarded the 2017 Nobel Prize in Physiology or Medicine to three researchers for their discoveries of molecular mechanisms that control the circadian rhythm, popularly known as the “biological clock.” The work of Jeffrey C. Hall of the University of Maine, Orono; Michael Rosbash of Brandeis University; and Michael W. Young of Rockefeller University helped explain how a living being’s biological rhythm is synchronized with the Earth’s revolutions, according to a press release from the National Institutes of Health. The three laureates are NIH grantees.
The work helped explain how a living being’s biological rhythm is synchronized with the Earth’s revolutions.
“The work of these Nobel laureates to help us understand how our biological clocks work has shone a light on the significance of circadian rhythms on our health, and is informing treatments for sleep disorders, obesity, mental health disorders, and other health problems,” said NIH Director Francis S. Collins.
Building on the work of previous researchers who had demonstrated that a so-called “period” gene controls circadian rhythm in fruit flies, Hall, Rosbash, and Young isolated the gene and discovered that the protein it produces accumulates during the night, blocking the gene’s activity, and degrades during the day. Subsequent work explained how other genes and proteins work in tandem to establish a 24-hour cycle.
“We now know that all multicellular organisms, including humans, utilize a similar mechanism to control circadian rhythms,” reads the press release from the Royal Swedish Academy of Sciences. “A large proportion of our genes are regulated by the biological clock and, consequently, a carefully calibrated circadian rhythm adapts our physiology to the different phases of the day.”
The work of Hall, Rosbash, and Young has particular relevance for OEHS professionals responsible for workers who participate in shift work. Because it disrupts normal periods of sleep and wakefulness, shift work can increase risks both to workers’ safety—for example, through drowsy driving—and their long-term health.
The International Agency for Research on Cancer classifies shift work as Group 2A, probably carcinogenic to humans (PDF). IARC’s determination was based on studies of nurses and flight attendants, which showed that women engaged in long-term night work have a higher risk of breast cancer. According to IARC, other studies of animals suggest a link between constant light and significant increases in tumor development.
In a 2007 press release announcing the addition of shift work to Group 2A, IARC stated that interruptions to circadian rhythm might account for the association between shift work and increased tumors. Exposure to light at night “can alter sleep-activity patterns, suppress melatonin production, and disregulate genes involved in tumor development,” IARC stated. “Among the many different patterns of shiftwork, those that include nightwork are most disruptive to the circadian system.”
A 2012 post to the NIOSH Science Blog recommends that workers have at least 10 consecutive hours off work to allow for at least 7 hours of uninterrupted sleep. Rest breaks every 1 to 2 hours, and more frequently for physically demanding work, can help workers avoid fatigue. Eight- and ten-hour shifts are desirable, while twelve-hour shifts may be acceptable if workers have additional days for rest.
For more information about the 2017 Nobel Prize in Physiology or Medicine, visit the official Nobel Prize website or read NIH's press release.

NIOSH addresses the topic of shift work on one of its workplace safety and health topic pages and on its blog.