Unclear tasks and command structures increase fatigue in disaster responders

Hiroshima University

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Researchers conducting surveys of disaster responders during the 2024 Noto Peninsula earthquake response. (Photo provided by Tatsuhiro Nagata / Hiroshima University)

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Credit: Photo provided by Tatsuhiro Nagata / Hiroshima University

Real time data collected during the 2024 Noto Peninsula earthquake response show that unclear tasks and command structures, and lack of meal- and rest breaks increased self-reported fatigue among disaster responders.

The frequency of natural disasters is increasing, and hence disaster responders are called on more than ever before. During disaster response, the focus of health and well-being is typically on the residents of the disaster-impacted zones. The health and well-being of disaster responders have been given less importance despite the vital role they play; however, managing it is a critical issue to increase the success of recovery efforts.

A research team led by Hiroshima University has used real-time data collected from disaster responders during the 2024 Noto Peninsula earthquake response. Using this data, they identified key factors associated with self-reported fatigue, identifying possibilities to improve the health and well-being of disaster responders while responding to disasters. 

Their findings were published in the journal Safety and Health at Work on March 18, 2026.

During the 2024 Noto Peninsula earthquake response, the Japanese Surveillance in Post-extreme Emergencies and Disasters (J-SPEED+) app was used to monitor disaster responders’ health and well-being in real time through daily surveys. This was the first time such data was collected, presenting a unique dataset for analysis; typically, such data is collected retrospectively, once the response is complete.

The research team says that their study seeks to understand what specific factors actually drive fatigue during disaster response. When responders are fatigued, their ability to think clearly, make decisions, and provide safe care can be compromised. This can affect not only their own health but also the safety and outcomes of the people they are trying to help. In this way, fatigue becomes a broader public safety and system-level concern, rather than an individual issue.

During the 2024 Noto Peninsula earthquake response, the Health Emergency Operations Center (HEOC) of Ishikawa collected data from disaster responders via J-SPEED＋ from Jan 1 to Mar 31, 2024. The data consisted of 46 checkbox questions across eight sections: organization name, type of occupation, type of activity, problems in the work environment, symptoms, work performance, fatigue, and consultation requests. The occupations of disaster responders included doctors, nurses, logisticians, other health and welfare support staff, administrative supporters, and others; and the types of activities were HEOC, field work, and others. Fatigue was measured daily using a 10-point scale (1 = minimal and 10 = extreme), adapted from the visual analog scale for assessing fatigue developed by the Japan Society of Fatigue.

The research team statistically analyzed 15,067 records containing complete data. The disaster response was broken into two phases: Jan 1 to Feb 6 (first phase) and Feb 6 to Mar 31 (second phase). The relationship between fatigue scores and other factors was analyzed. Of the 15,067 records—representing 5,569 individuals —9,583 were collected during the first phase and 5,484 during the second phase. Occupationally, contributions to the records were mainly from logisticians (32.9%), nurses (29.6%), doctors (21.5%). Field staff contributed most of the data entries (65.8%), and HEOC staff and other responders contributed fewer entries.

The researchers found that fatigue scores had greater variability in the first phase, while the second phase had less variability. 73.7% of all fatigue scores ranged from 1 to 3 during the first phase, and this percentage was 82.3% during the second phase.

‘Unsafe work environment,’ ‘inability to take meals and breaks’ significantly associated with higher fatigue

The researchers determined that responders working in administrative support and logisticians had greater fatigue, possibly due to demanding daily unfamiliar and non-routine tasks. Additionally, responders working at an HEOC had greater fatigue due to their role in coordinating the support for medical personnel and supplies, which involves high cognitive demand and requires rapid decision-making about non-routine tasks.

Higher fatigue scores were associated with unclear tasks and commands. Previous Japanese and global studies have indicated similar associations. Specifically, after the 2011 Great East Japan Earthquake, responders performing ‘diverse tasks unlike during peacetime’ reported chronic fatigue due to ill-defined roles.

They also showed that ‘unsafe work environment’ and ‘inability to take meals and breaks’ were significantly associated with higher fatigue. The inclement weather and lack of rest during the earthquake response likely intensified the physical and psychological burdens on responders. Finally, insecure communication can lead to responder fatigue, especially in the early phase of disasters.

“Our most striking finding was that problems in coordination or command systems significantly increased fatigue,” explains Tatsuhiro Nagata, researcher at the Graduate School of Biomedical and Health Sciences, and first author of the paper. “This means that confusion, unclear instructions, or poor management can exhaust responders almost as much as physical work itself. Moreover, the impact of missing breaks and meals was stronger than many individual characteristics such as role or experience. Put simply, ddisaster responders are like the engine of an emergency response — [and] if the system does not provide fuel (rest, food, coordination), even the strongest engine will fail.”

Nagata continues, “Responders can remain healthier, safer, and more effective in their roles by improving planning, ensuring regular breaks, and strengthening coordination and management systems.”

The research team proposed policy and practical implications to manage the health and well-being of disaster responders. First, it is essential to establish structured fatigue management protocols, such as scheduled rest, meal breaks, and access to health support. There is also a need to strengthen command clarity and role definition through regular preparedness exercises and simulation-based training. Finally, maximizing the utility of the J-SPEED + Health app is essential. Clear user guidelines and motivation strategies should be provided to encourage consistent real-time health reporting.

Their ultimate goal is to create a disaster response system where responders can work safely, sustainably, and effectively — so they can continue to care for others without compromising their own health. Rather than simply recognizing that responders become fatigued, the goal is to actively redesign the system to prevent unnecessary exhaustion.

Yamato Sasaki, Odgerel Chimed-Ochir, Inn Kynn Khaing, Hanako Murayama, Akihiro Taji, Noriyuki Shiroma, Ami Fukunaga, Yui Yumiya, and Tatsuhiko Kubo at Hiroshima University; and Seiichiro Tateishi, Nahoko Enokida, Koji Mori, and Yoshihisa Fujino at the University of Occupational and Environmental Health contributed to the study. Odgerel Chimed-Ochir was the corresponding author of the study.

The study was supported by Japan Science and Technology Agency (JST) SPRING (JPMJSP2132). 

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About Hiroshima University
Since its foundation in 1949, Hiroshima University has striven to become one of the most prominent and comprehensive universities in Japan for the promotion and development of scholarship and education. Consisting of 12 schools for undergraduate level and 5 graduate schools, ranging from natural sciences to humanities and social sciences, the university has grown into one of the most distinguished comprehensive research universities in Japan. English website: https://www.hiroshima-u.ac.jp/en

 

Associations between studied factors and fatigue in disaster responders during the 2024 Noto Peninsula earthquake response. Inability to take meals and breaks, and unclear tasks and command structures had the greatest influence on fatigue. (Tatsuhiro Nagata / Hiroshima University)

Credit

Tatsuhiro Nagata / Hiroshima University

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Journal

Safety and Health at Work

DOI

10.1016/j.shaw.2025.11.003 

Method of Research

Data/statistical analysis

Subject of Research

People

Article Title

Key Contributors to Fatigue in Disaster Responders: Analysis of the 2024 Noto Peninsula Earthquake

 

Tropical primary forest plants up-regulate root exudation to adapt to long-term high nitrogen deposition

South China Botanical Garden, Chinese Academy of Sciences

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Results showed that plants evolved an active adaptation mechanism under chronic high N addition: (i) increased root C exudation rate to stimulate microbial phosphatase activity and accelerated the mineralization of organic P; (ii) enhanced the release of organic acids to promote the dissolution of mineral-bound P. More importantly, the organic acid pathway played a dominant role, driving approximately twice as much P release as the phosphatase pathway.

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Credit: Xiaomin Zhu, Ziliang Zhang, Benjamin L. Turner, Weibin Chen, Qinggong Mao, Andi Li, Jiangming Mo, Xiankai Lu

Date: May 26, 2026

Guangzhou, China: A research team led by Prof. Xiankai Lu at the South China Botanical Garden, Chinese Academy of Sciences, investigated how tropical forest plants adapt to chronic high N addition by regulating root exudates and rhizosphere phosphorus dynamics in a primary broadleaf forest. Chronic high N addition increased root carbon exudation, stimulating phosphatase activity to mineralize organic P, and enhanced organic acid release to dissolve mineral-bound P. The organic acid pathway drove twice as much P release as the phosphatase pathway. This is the first evidence that tropical plants actively up‑regulate root exudation to adapt to long-term N deposition, explaining their sustained high productivity and offering crucial insights for predicting forest carbon sinks under climate change.

Intensifying global nitrogen (N) deposition has disrupted the N-P balance in ecosystems, particularly in tropical and subtropical regions where available P is relatively scarce. Extensive studies in temperate N-limited ecosystems have led to a classic paradigm: N addition alleviates plant competition for N, thereby reducing the allocation of photosynthates belowground, especially decreasing the release of root exudates. However, whether this paradigm can be directly applied to "N-rich" but P-deficient tropical and subtropical forests has long lacked experimental evidence, becoming a critical knowledge bottleneck for predicting forest C-P feedback and ecosystem stability under high N deposition.

To address this issue, a research team led by Prof. Xiankai Lu at the South China Botanical Garden, Chinese Academy of Sciences, conducted an in-situ study to investigate how tropical forest plants adapt to chronic high N addition by regulating root exudates and rhizosphere P dynamics in a primary broadleaf forest. The results showed that plants evolved an active adaptation mechanism when facing chronic high N addition: (i) increased root C exudation rate to stimulate microbial phosphatase activity and accelerate the mineralization of organic P; (ii) enhanced the release of organic acids to promote the dissolution of mineral-bound P. More importantly, the organic acid pathway played a dominant role, driving approximately twice as much P release as the phosphatase pathway.

This study provides the first evidence that tropical plants can adapt to long-term high N deposition by up-regulating root exudation, revising the traditional view that N deposition reduces belowground C allocation. This finding not only explains how "N-rich" tropical forests maintain high productivity and stability, but also suggests that ecosystems may possess more complex proactive adaptation strategies when facing chronic environmental stress. This insight is crucial for predicting the dynamics of tropical forest carbon sinks under future climate change.

 

Original Source：

Zhu X., Zhang Z., Turner B. L., Chen W., Mao Q., Li A., Mo J., Lu X., 2026. Enhanced Root Exudation as an Adaptation Mechanism to Facilitate Phosphorus Mobilization in a Primary Tropical Forest Under Chronic Nitrogen Deposition. Global Change Biology 32(5): e70912

https://doi.org/10.1111/gcb.70912

 

Keywords: carbon allocation, N-induced P deficiency, nitrogen addition, root exudation, soil P cycling, tropical forests

 

About the Author

Xiaomin Zhu (First author): South China Botanical Garden, Chinese Academy of Sciences. Research interests include global change ecology, mycorrhizosphere ecology, plant-soil-microbe interactions, and soil carbon sequestration.

Xiankai Lu (Corresponding author): South China Botanical Garden, Chinese Academy of Sciences. His research focuses on responses and adaptative mechanisms of forest ecosystem structure and function to global environmental change.

 

About the journal

Global Change Biology is an environmental change journal dedicated to shaping the future and solving the world's most challenging problems by tackling sustainability, climate change and environmental protection, food and water security and supply, as well as global health. The journal aims to advance understanding of the impacts of global change on biological systems and solutions. Examples include:

1. rising tropospheric ozone, carbon dioxide and sulphur dioxide concentrations
2. increasing UV-B irradiation
3. global climate change
4. biological sinks and sources of atmospheric trace gases
5. eutrophication
6. land use change
7. biodiversity loss
8. biological feedback to climate change
9. biological mitigation of atmospheric change
10.  

About the Institution

Affiliated with the Chinese Academy of Sciences, South China Botanical Garden (SCBG) is one of China's earliest botanical research institutions. It was founded in 1929 by Academician Huan-Yong Chen (Woon-Young Chun) and officially designated as a national botanical garden in 2022. Focusing on South China, it commits to plant conservation, scientific research and science popularization across tropical and subtropical regions, and provides scientific underpinnings for ecological and green development. As a leading institution for plant germplasm conservation, SCBG has attained outstanding achievements since 1988: it has published over 540 monographs, issued more than 6,900 SCI-indexed papers, won over 350 scientific awards, obtained more than 630 patents, and bred over 410 new plant varieties. Its research work is strongly supported by three core academic divisions and a number of field research stations.   

 

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Journal

Global Change Biology

DOI

10.1111/gcb.70912 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Enhanced Root Exudation as an Adaptation Mechanism to Facilitate Phosphorus Mobilization in a Primary Tropical Forest Under Chronic Nitrogen Deposition

Article Publication Date

15-May-2026

COI Statement

Ethics Statement Field sample collection were approved and conducted in compliance with the relevant national laws and local regulations. Conflicts of Interest The authors declare no conflicts of interest.

From environmental crisis to climate opportunity: New study shows how Atlantic seaweed could power carbon removal and biofuels

CMCC Foundation - Euro-Mediterranean Center on Climate Change

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Across the Caribbean, Gulf of Mexico, and West African coasts, massive arrivals of Sargassum seaweed have become an annual crisis. Thick mats of algae blanket beaches, disrupt fisheries, damage tourism, and release harmful gases as they decay, with cleanup costs reaching hundreds of millions of dollars each year. What began as an unexpected environmental phenomenon has grown into a persistent socio-economic challenge affecting multiple regions on both sides of the Atlantic.

A new study by international researchers, led by CMCC scientist Annalisa Bracco, now suggests that this growing problem could also represent an untapped opportunity. The research, “Changing Drivers of the Great Atlantic Sargassum Belt from Physical Forcing to Ecological Control,” shows that the vast blooms of Sargassum are not only likely to persist, but may be predictable. This is significant because being able to predict blooms greatly increases our chances of using them for climate solutions such as marine carbon dioxide removal and biofuel production.

The so-called Great Atlantic Sargassum Belt appeared in 2011 and has since expanded into a transoceanic system stretching over 8,000 kilometers from West Africa to the Caribbean. By 2025, its biomass exceeded 37 million tons – about six times the total body mass of Italy’s population. While this expansion has amplified its impacts on coastal communities, it also represents an enormous, naturally occurring pool of carbon captured through photosynthesis.

“Sargassum absorbs large amounts of carbon dioxide as it grows,” explains Bracco. “The key challenge is that when it reaches the coast and decomposes, much of that carbon is released back into the atmosphere. If we can intervene before this happens, this system could instead be part of the solution.”

The study reveals that the drivers behind Sargassum growth have fundamentally changed over time. In its early years, the expansion of the belt was primarily driven by physical processes, particularly stronger winter winds that deepened the ocean’s mixed layer and brought nutrients to the surface. Over time, however, the system has evolved into a self-sustaining ecosystem. Sargassum hosts entire communities of marine organisms that recycle nutrients – especially nitrogen – within the floating mats, while decaying algae release additional nutrients back into the water. This internal ability to regenerate nitrogen has created a feedback loop that allows for growth even in the absence of wind events, and has become the dominant driver in recent years.

Using a model based on satellite observations and oceanographic data, the researchers reconstructed Sargassum variability from 2011 to 2022 and successfully predicted concentrations for 2023 and 2024. This predictive capability is a crucial step forward, as it reduces uncertainty about the future of the blooms and makes long-term planning feasible. The study also shows that the system is now largely self-sustaining through an internal ecological feedback, making natural decline unlikely and reinforcing the need for long-term management strategies.

The persistence and predictability of the Great Atlantic Sargassum Belt suggest opportunities to turn it from a burden into a resource, including offshore harvesting for deep-ocean carbon storage or conversion into biofuels and other materials, with potential benefits for emissions reduction and cleanup costs.

“It’s a striking example of how the ocean can reorganize itself very quickly,” says Bracco. “What started as a wind-driven event has become a self-sustaining biological system. The fact that we can now understand and predict it means we can also start thinking seriously about how to manage it.”

The findings provide a scientific foundation for policymakers, investors, and coastal nations to explore long-term solutions that combine environmental protection with climate innovation.

 

More information:

Zhou, X., Novi, L., Hay, M.E. et al. Changing drivers of the Great Atlantic Sargassum Belt from physical forcing to ecological control. Nat Commun 17, 4600 (2026). https://doi.org/10.1038/s41467-026-72183-4

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Journal

Nature

 

Travel dating apps and the emotional risks of intimacy

New research finds queer travellers use apps like Grindr not just for sex, but for fantasy, identity, connection and self-exploration.

University of East London

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New research shows that gay dating apps during travel can bring excitement and connection - but also emotional exhaustion, catfishing, and vulnerability.

Dating apps are changing not only how people connect while travelling, but also how they experience desire, loneliness, and emotional wellbeing, according to a new study published in Annals of Tourism Research.

The research, based on interviews with queer male travellers, introduces the idea of “cyber-sexual leisure” to describe the intense digital interactions that shape modern travel experiences - including browsing profiles, flirting, sexting, exchanging photos, fantasising, and seeking connection.

But the study found these experiences were often emotionally complicated. While apps can create excitement, they can also lead to emotional fatigue, risky situations, and feelings of emptiness.

Lead author Dr Oliver Qiu, from the University of East London, said:

“People often assume these apps are only about casual sex. But what participants described was much more emotionally intense and psychologically complicated.

“Many people experienced cycles of anticipation, excitement, rejection, validation, disappointment, and emotional exhaustion - sometimes all within a single trip.”

Participants described using dating apps while travelling not only to arrange sex, but also to cope with boredom, insecurity, and the emotional intensity of being in unfamiliar places.

Some interviewees compared the experience to a “dopamine hit”, where browsing and receiving attention became addictive forms of emotional stimulation during travel.

At the same time, participants also described darker experiences.

One participant described meeting someone abroad who looked different from their profile photos before being pressured into a threatening situation involving money. Others described feeling emotionally pressured into sex after spending hours chatting online or travelling to meet someone.

Dr Qiu, from the Royal Docks School of Business and Law, said:

“What makes these experiences powerful is that pleasure and vulnerability often happen together. The same apps that create excitement and connection can also produce emotional pressure, disappointment, and risk.

“Travel can intensify all of this because people are outside their normal routines, more anonymous, emotionally exposed, and often searching for connection in unfamiliar environments.”

The study argues that digital intimacy has become a major part of how many people now experience travel. Rather than simply using apps to arrange physical encounters, participants described apps becoming woven into the emotional atmosphere of travelling.

The researchers say the findings have wider relevance beyond tourism, particularly as dating apps and digital intimacy continue to shape emotional life, relationships, and wellbeing more broadly.

Qiu, X. (Oliver), Scott Cohen & Jonathan Skinner. (2026). “Digital Intimacies in Motion: Redefining Sex in Tourism.” Annals of Tourism Research, is available online.

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Journal

Annals of Tourism Research

DOI

10.1016/j.annals.2026.104206 

Method of Research

Observational study

Article Title

Digital intimacies in motion: Redefining sex in tourism

Article Publication Date

15-May-2026

 

Magic mushroom chemical cuts nerve pain and enhances drug

University of Reading

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A single dose of psilocybin — the active compound in magic mushrooms — reduces nerve pain for up to a month and makes a widely used painkiller work more effectively, University of Reading research has found. 

The study, published in Communications Biology, tested psilocybin in mice with nerve damage that causes long-lasting pain. Researchers found that psilocybin's pain-relieving effect appeared around two hours after injection, with relief lasting several weeks. Rather than simply blocking pain signals, psilocybin appears to restructure the way the brain's pain-processing networks operate, which may explain why its effects persist long after the drug itself has left the body. 

The most significant finding was how psilocybin interacted with gabapentin, a drug widely prescribed for nerve pain. When gabapentin was given to mice weeks after a single psilocybin dose, after psilocybin's own pain-relieving effect had worn off, it produced pain relief lasting up to four days. In mice that had not received psilocybin, gabapentin's effect was much weaker. 

Between 30 and 50 percent of people with nerve pain do not get adequate relief from gabapentin alone.  

Dr Maria Maiarú, senior author from the University of Reading, said: "Millions of people live with nerve pain that their medication simply does not control well enough, and the medicines we do have can cause serious side effects or lead to addiction. What is exciting here is that psilocybin does not just reduce pain on its own. It appears to reset the brain's pain networks in a way that makes existing treatments significantly more effective. For patients who have run out of options, that could be genuinely transformative." 

The pain-relieving effect was confirmed in both male and female mice, which is significant given that much early pain research was conducted in male animals only. The study used a small number of mice in line with UK Home Office regulations and the 3Rs principles of Replacement, Reduction and Refinement. Procedures were designed to minimise distress, and where possible multiple outcomes were measured from the same animals to keep numbers down. 

There are more ways to find out more about animal research at Reading:   

• Sign up to attend our public lecture on Thursday, 4 June: The Past Present and Future of Animal Research at Reading  

• Find out more about recent animal-related research: Animal research at Reading: past, present and future 

• View the Animal Research at Reading webpage 

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Journal

Communications Biology

DOI

10.1038/s42003-026-10065-7 

Article Title

Psilocybin ameliorates neuropathic pain-like behaviour in mice and facilitates gabapentin-mediated analgesia

Article Publication Date

22-May-2026