UNC Scientists are Feeling the (Circadian) Rhythm

Circadian rhythms -- the physical and mental responses to light and dark that follow the earth's 24-hour cycle -- influence a broad array of biological processes.

Researchers have long identified genes that orchestrate circadian rhythms in people, mice, fruit flies, fungi and other organisms.

But now, scientists at the University of North Carolina School of Medicine have detected how the protein cryptochrome (which acts as the core component of molecular internal "clocks" in mammals) resets the clock, shedding light on cryptochrome's relationship to everything from the sleep-wake cycles to cancer development to sleep disorders and jet lag to depression and cancer.

When cryptochrome is exposed to blue light in fruit flies, a millisecond of light exposure results in a half-life during which scientists can analyze the mechanism, said lead study author Aziz Sancar, MD, PhD, the Sarah Graham Kenan Professor of Biochemistry and Biophysics in the UNC School of Medicine.

Sancar went on to explain how following the molecular signals after light exposure results in a reliable model to see how light interacts with circadian systems, allowing scientists to test various hypotheses.