Julia Stone: PeerJ Award Winner at ACS 2022

The Australasian Chronobiology Society was founded in early 2004. The ACS aims to generate and discuss research in all areas of Chronobiology, including both animal and human work to examine specific areas such as sleep and circadian biology in Australia and New Zealand. Our annual scientific meeting brings together both local and international researchers interested in the influence of circadian rhythms on behaviour, cognition, sleep and health. The 19th meeting was held on the 7th of November, 2022, at Customs House, Brisbane. This was the Society’s first in-person meeting since 2019, and it was a wonderful day to gather in person again and hear from a number of speakers across both basic and applied aspects of circadian science.

Our keynote speaker for the 2022 meeting was Professor Greg Murray. Professor Murray is Director of the Centre for Mental Health at Swinburne University of Technology in Melbourne. He conducts research into mood disorders, circadian rhythms, and personality. He is ranked in the top 1% of researchers worldwide in each of these fields, and is recognised as a world expert in bipolar disorder. Professor Murray delivered his talk “Biological rhythms and mental health: Emerging questions”, which sparked brilliant discussion about how we can apply circadian principles clinically in order to improve the management of mental health conditions. 

Elise McGlashan, ACS Conference Organiser

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Julia Stone Research Fellow at the Turner Institute for Brain and Mental Health, Monash University, Australia.

Can you tell us a bit about yourself and your research interests?

I am interested in how circadian disruption occurs, and the subsequent impacts on health and wellbeing. In particular my research works with physiological models to help us understand how our circadian system responds to different challenges, such as shift work, or developmental changes, such as occur during adolescence, and also to work towards personalised circadian medicine by combining computational approaches with wearable technologies.

What first interested you in this field of research?

I first heard about circadian rhythms in high school, where my Psychology teacher taught us about how adolescents experience a real, physiological delay in their body clocks, making it very difficult to wake up early for school. As a teen this resonated strongly, especially when he suggested we protest and demand later school start times, but it wasn’t until working in a sleep laboratory during my Honours year, and subsequently during my PhD, that I really developed a strong need to understand how the body clock works, and what we can do to maintain optimal circadian health.

Can you briefly explain the research you presented at ACS 2022?

At ACS this year I presented some new work from our lab investigating how evening home lighting can be used to offset individual variations in circadian light sensitivity, to maintain stable circadian timing. We are increasingly learning that there is vast variability in how sensitive people are to light, which can easily lead to circadian disruption and difficulty sleeping. We wanted to see how differences in an individual’s light sensitivity interacts with different evening home lighting environments.

We used a validated computational model of the human circadian system to simulate sleep and circadian timing across two weeks, varying two conditions (1) how sensitive the system is to light (changing the dose-response curve to light), and (2) evening light levels in the home. We found that higher light sensitivity and higher evening light levels resulted in systematically later predicted sleep and circadian timing. The effects of increasing light sensitivity could be offset by reducing the levels of evening lighting. Our results show how modifications to evening light levels can be used to offset impacts of variable light sensitivity on sleep and circadian timing.

How will you continue to build on this research?

Next steps for this research project (beyond writing up the paper!) are to explore how we can use this approach to form a kind of map that can inform interventions for home lighting, tailored according to an individual’s circadian light sensitivity.

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