Are you messing with your body clock?

Researchers are employing mathematical models to better understand the effects of interruptions to the body's circadian rhythms such as daylight savings time, working night shifts, jet lag, or even late-night phone scrolling.

The University of Waterloo and the University of Oxford researchers have created a novel model to aid scientists in better understanding the robustness of the brain's master clock: the cluster of neurons in the brain that coordinates the body's other internal rhythms.

They also want to offer approaches to help individuals with weak or damaged circadian rhythms increase their resilience. Sustained disruptions to circadian rhythm have been linked to diabetes, memory loss, and many other disorders.

“Current society is experiencing a rapid increase in demand for work outside of traditional daylight hours,” said Stéphanie Abo, a PhD student in applied mathematics and the study’s lead author, adding, “This greatly disrupts how we are exposed to light, as well as other habits such as eating and sleeping patterns.”

Humans’ circadian rhythms, or internal clocks, are the roughly 24-hour cycles many body systems follow, usually alternating between wakefulness and rest. Scientists are still working to understand the cluster of neurons known as the Suprachiasmatic Nucleus (SCN) or master clock.

Using mathematical modelling techniques and differential equations, the team of applied mathematics researchers modelled the SCN as a macroscopic, or big-picture, system comprised of a seemingly infinite number of neurons.

They were especially interested in understanding the system’s couplings – the connections between neurons in the SCN that allow it to achieve a shared rhythm.

Frequent and sustained disturbances to the body’s circadian rhythms eliminated the shared rhythm, implying a weakening of the signals transmitted between SCN neurons. Abo said they were surprised to find that “a small enough disruption can actually make the connections between neurons stronger.”

“Mathematical models allow you to manipulate body systems with specificity that cannot be easily or ethically achieved in the body or a petri dish,” Abo said, adding, “This allows us to do research and develop good hypotheses at a lower cost.”