Active Psychology & Behaviour Mental Health

Circadian Light Sensitivity as a Mechanism for PTSD Vulnerability

Funder Wellcome Charity-funded
Associated organisations Flinders University · Harvard University · The University of Melbourne Europe PMC affiliations are not treated as award recipients or mapped locations.
Funding £3.1M
Period Nov 2024 — Oct 2029

In plain English

AI plain-English summary

A single night of bright light after a traumatic event may be enough to tip someone with a sensitive circadian system into developing PTSD. Most people recover naturally after trauma, but around one in three do not, and current treatments only work after PTSD has already taken hold. This project targets the moment before that happens. The researchers have shown that the circadian system—the body’s internal clock—can be disrupted by light at night, and that people vary in how sensitive their clock is to that disruption. The hypothesis is that this sensitivity makes some individuals more vulnerable to PTSD. The project will test that mechanism genetically and physiologically, and then run a randomised controlled trial of a simple, low-cost intervention: adjusting night-time light exposure to protect the circadian system. If the mechanism is confirmed, the impact is twofold. First, a cheap, scalable behavioural intervention could be deployed in emergency settings—hospital wards, military barracks, disaster shelters—to reduce PTSD rates. Second, a simple measure of circadian light sensitivity could identify who is most at risk, enabling targeted prevention before symptoms appear. The work is guided by a PTSD Lived Experience Working Group, ensuring the research addresses real-world needs.

View original technical description
Light regulates circadian rhythms, and unhealthy light exposure patterns have negative impacts on mental health. Disrupted circadian rhythms have been associated with posttraumatic stress disorder (PTSD), but the causal mechanisms are currently unknown. Our recent research indicates that the sensitivity of the circadian system to the disruptive effects of light at night likely plays a key role in PTSD development. This project will investigate the mechanistic hypothesis that light exposure at night increases the risk of developing PTSD after a traumatic event, and that people with higher light sensitivity are therefore at elevated risk. We propose four work packages to elucidate the physiological and genetic contributions of circadian light sensitivity and circadian disruption to PTSD risk. We will also test a highly feasible, cost-effective intervention designed to protect against PTSD by reducing disruptive effects of night light exposure on the circadian system in a randomised controlled trial. Our work will be guided by a PTSD Lived Experience Working Group. Beyond determining the causal mechanisms that implicate the circadian system in PTSD, our findings will enable new measures to identify individuals who are most likely to develop PTSD. This will lead to targeted countermeasures which could help to prevent PTSD onset.

View the original record at the funder ↗

Researchers

Andrew Phillips (EPMC Awardee)Angus Burns (EPMC Awardee)Tim Peck (EPMC Awardee)

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Original classification

Mental Health Award: Understanding anxiety and trauma

Plain English summaries and category classifications on this site are generated by AI and may not perfectly reflect the original research.