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Li Y, Androulakis IP. The SCN-HPA-Periphery Circadian Timing System: Mathematical Modeling of Clock Synchronization and the Effects of Photoperiod on Jetlag Adaptation. J Biol Rhythms 2023; 38:601-616. [PMID: 37529986 PMCID: PMC10615703 DOI: 10.1177/07487304231188541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/03/2023]
Abstract
Synchronizing the circadian timing system (CTS) to external light/dark cycles is crucial for homeostasis maintenance and environmental adaptation. The CTS is organized hierarchically, with the central pacemaker located in the suprachiasmatic nuclei (SCN) generating coherent oscillations that are entrained to light/dark cycles. These oscillations regulate the release of glucocorticoids by the hypothalamus-pituitary-adrenal (HPA) axis, which acts as a systemic entrainer of peripheral clocks throughout the body. The SCN adjusts its network plasticity in response to variations in photoperiod, leading to changes in the rhythmic release of glucocorticoids and ultimately impacting peripheral clocks. However, the effects of photoperiod-induced variations of glucocorticoids on the synchronization of peripheral clocks are not fully understood, and the interaction between jetlag adaption and photoperiod changes is unclear. This study presents a semi-mechanistic mathematical model to investigate how the CTS responds to changes in photoperiod. Specifically, the study focuses on the entrainment properties of a system composed of the SCN, HPA axis, and peripheral clocks. The results show that high-amplitude glucocorticoid rhythms lead to a more coherent phase distribution in the periphery. In addition, our study investigates the effect of photoperiod exposure on jetlag recovery time and phase shift, proposing different interventional strategies for eastward and westward jetlag. The findings suggest that decreasing photic exposure before jetlag during eastward traveling and after jetlag during westward traveling can accelerate jetlag readaptation. The study provides insights into the mechanisms of CTS organization and potential recovery strategies for transitions between time zones and lighting zones.
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Affiliation(s)
- Yannuo Li
- Department of Chemical & Biochemical Engineering, Rutgers University-New Brunswick, New Brunswick, New Jersey, USA
| | - Ioannis P Androulakis
- Department of Chemical & Biochemical Engineering, Rutgers University-New Brunswick, New Brunswick, New Jersey, USA
- Department of Biomedical Engineering, Rutgers University, Piscataway, New Jersey, USA
- Department of Surgery, Robert Wood Johnson Medical School, Rutgers University-New Brunswick, New Brunswick, New Jersey, USA
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Jones DL, Rhymes JM, Green E, Rimmer C, Kevill JL, Malham SK, Weightman AJ, Farkas K. Poor air passenger knowledge of COVID-19 symptoms and behaviour undermines strategies aimed at preventing the import of SARS-CoV-2 into the UK. Sci Rep 2023; 13:3494. [PMID: 36859503 PMCID: PMC9976683 DOI: 10.1038/s41598-023-30654-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 02/27/2023] [Indexed: 03/03/2023] Open
Abstract
Air travel mediates transboundary movement of SARS-CoV-2. To prepare for future pandemics, we sought to understand air passenger behaviour and perceived risk during the COVID-19 pandemic. This study of UK adults (n = 2103) quantified knowledge of COVID-19 symptoms, perceived health risk of contracting COVID-19, likelihood of returning to the UK with COVID-19 symptoms, likelihood to obey self-quarantining guidelines, how safe air travellers felt when flying during the pandemic (n = 305), and perceptions towards face covering effectiveness.Overall knowledge of COVID-19 symptoms was poor. Men and younger age groups (18-44) were less informed than women and older age groups (44 +). A significant proportion (21%) of the population would likely travel back to the UK whilst displaying COVID-19 symptoms with many expressing that they would not fully comply with self-isolation guidelines. Overall, males and younger age groups had a reduced perceived personal risk from contracting COVID-19, posing a higher risk of transporting SARS-CoV-2 back to the UK. Poor passenger knowledge and behaviour undermines government guidelines and policies aimed at preventing SARS-CoV-2 entry into the UK. This supports the need for stricter, clearer and more targeted guidelines with point-of-departure viral testing and stricter quarantining upon arrival.
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Affiliation(s)
- David. L. Jones
- grid.7362.00000000118820937Centre for Environmental Biotechnology, School of Natural Sciences, Bangor University, Bangor, LL57 2UW Gwynedd UK ,grid.1025.60000 0004 0436 6763SoilsWest, Centre for Sustainable Farming Systems, Food Futures Institute, Murdoch University, Murdoch, WA 6105 Australia
| | - Jennifer M. Rhymes
- grid.7362.00000000118820937Centre for Environmental Biotechnology, School of Natural Sciences, Bangor University, Bangor, LL57 2UW Gwynedd UK ,grid.494924.60000 0001 1089 2266UK Centre for Ecology and Hydrology, Environment Centre Wales, Bangor, LL57 2UW Gwynedd UK
| | - Emma Green
- grid.7362.00000000118820937Centre for Environmental Biotechnology, School of Natural Sciences, Bangor University, Bangor, LL57 2UW Gwynedd UK
| | - Charlotte Rimmer
- grid.7362.00000000118820937Centre for Environmental Biotechnology, School of Natural Sciences, Bangor University, Bangor, LL57 2UW Gwynedd UK
| | - Jessica L. Kevill
- grid.7362.00000000118820937Centre for Environmental Biotechnology, School of Natural Sciences, Bangor University, Bangor, LL57 2UW Gwynedd UK
| | - Shelagh K. Malham
- grid.7362.00000000118820937School of Ocean Sciences, Bangor University, Menai Bridge, LL59 5AB Anglesey UK
| | - Andrew J. Weightman
- grid.5600.30000 0001 0807 5670Microbiomes, Microbes and Informatics Group, School of Biosciences, Cardiff University, Cardiff, CF10 3AX UK
| | - Kata Farkas
- grid.7362.00000000118820937Centre for Environmental Biotechnology, School of Natural Sciences, Bangor University, Bangor, LL57 2UW Gwynedd UK ,grid.7362.00000000118820937School of Ocean Sciences, Bangor University, Menai Bridge, LL59 5AB Anglesey UK
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Kunorozva L, Rae DE, Roden LC. Dim light melatonin onset following simulated eastward travel is earlier in young males genotyped as PER35/5 than PER34/4. Chronobiol Int 2022; 39:1611-1623. [PMID: 36324294 DOI: 10.1080/07420528.2022.2139184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Inter-individual variability exists in recovery from jetlag following travel across time zones. Part of this variation may be due to genetic differences at the variable number tandem repeat (VNTR) polymorphism of the PERIOD3 (PER3) gene as this polymorphism has been associated with chronotype and sleep, as well as sensitivity to blue light on melatonin suppression. To test this hypothesis we conducted a laboratory-based study to compare re-entrainment in males genotyped as PER34/4 (n = 8) and PER35/5 (n = 8) following simulated eastward travel across six time zones. The recovery strategy included morning blue-enriched light exposure and appropriately-timed meals during the first 24 h after simulated travel. Dim light melatonin onset (DLMO), sleep characteristics, perceived sleepiness levels (Stanford Sleepiness Scale), and resting metabolic parameters were measured during constant routine periods before and after simulated travel. While DLMO time was similar between the two groups prior to simulated eastward travel (p = .223), it was earlier in the PER35/5 group (17h23 (17h15; 17h37)) than the PER34/4 group (18h05 (17h53; 18h12)) afterwards (p = .046). During resynchronisation, perceived sleepiness and metabolic parameters were similar to pre-travel in both groups but sleep was more disturbed in the PER35/5 group (total sleep time: p = .008, sleep efficiency: p = .008, wake after sleep onset: p = .023). The PER3 VNTR genotype may influence the efficacy of re-entrainment following trans-meridian travel when blue-enriched light exposure is incorporated into the recovery strategy on the first day following travel.
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Affiliation(s)
- Lovemore Kunorozva
- Department of Molecular and Cell Biology, University of Cape Town, Private Bag Rondebosch, Cape Town, South Africa.,Division of Sleep Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Dale E Rae
- Health through Physical Activity, Lifestyle and Sport Research Centre & Division of Physiological Sciences, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Laura C Roden
- Department of Molecular and Cell Biology, University of Cape Town, Private Bag Rondebosch, Cape Town, South Africa.,Health through Physical Activity, Lifestyle and Sport Research Centre & Division of Physiological Sciences, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Centre for Sport, Exercise and Life Sciences/School of Life Sciences, Coventry University, Coventry, UK
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Beh SF, Lee SKM, Bin YS, Cheung JMY. Travelers' perceptions of jetlag and travel fatigue: A scoping review. Chronobiol Int 2022; 39:1037-1057. [PMID: 35587565 DOI: 10.1080/07420528.2022.2072224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Effective management strategies for jetlag have largely been studied and evaluated through the lens of circadian science and biological rhythms. Jetlag is mostly self-managed by the individual. The most effective strategies require individuals to make behavioral changes to carefully alter sleep-wake schedules and time light exposure. However, travelers' perceptions, including their experiences, beliefs about jetlag/travel fatigue, and management expectations remain unclear. Therefore, the aim of this scoping review was to systematically synthesize the literature to understand what is currently known about travelers' perceptions of jetlag and travel fatigue. A literature search was conducted through EMBASE, PsycINFO, PubMed and Scopus generating 1164 results (2 articles known to authors), which were screened against our inclusion criteria. Twenty-two studies including data from 3952 participants were evaluated for its study design and traveler-centered outcome measures across the domains of: 1) Traveler Health Beliefs and Knowledge about Jetlag and Travel Fatigue; 2) Experience of Jetlag and Travel Fatigue 3) Traveler Priorities; 4) Self-reported Management Strategies for Jetlag and Travel Fatigue; and 5) User Experiences of Management Strategies. Synthesis of results suggests a potential mismatch between researchers' focus on circadian misalignment and travelers' focus on air travel comfort. A better understanding of the beliefs, attitudes, knowledge, satisfaction, experiences, and expectations about jetlag and travel fatigue will better enable the development of interventions that align with traveler priorities.
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Affiliation(s)
- Su Fern Beh
- Sydney Pharmacy School, Faculty of Medicine and Health, the University of Sydney, Sydney, Australia
| | - Samantha K M Lee
- Sydney Pharmacy School, Faculty of Medicine and Health, the University of Sydney, Sydney, Australia
| | - Yu Sun Bin
- Northern Clinical School, Faculty of Medicine and Health, the University of Sydney, Sydney, Australia.,Sleep Research Group, Charles Perkins Centre, the University of Sydney, Sydney, Australia
| | - Janet M Y Cheung
- Sydney Pharmacy School, Faculty of Medicine and Health, the University of Sydney, Sydney, Australia.,Sleep Research Group, Charles Perkins Centre, the University of Sydney, Sydney, Australia
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Beh SF, Holdik EN, Bin YS, Cheung JMY. Air travellers' experiences and understanding of jetlag and perceptions of management strategies: a qualitative study. ERGONOMICS 2022; 65:642-658. [PMID: 34615442 DOI: 10.1080/00140139.2021.1980112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 09/08/2021] [Indexed: 06/13/2023]
Abstract
Jetlag is largely self-managed by the individual traveller. This paper explores the lived experiences of air travellers, their understanding of jetlag, and their perceptions of management strategies. 32 international travellers (mean age = 31, SD: 15 years; 47% female, mean flight duration = 16, SD: 6 hours) were interviewed. Interviews were recorded, transcribed verbatim and analysed using the Framework Approach. Analysis of the qualitative data revealed three emergent themes: Travel beliefs and experiences, Impact of jetlag, and Approaches to jetlag management. Participants' experience of jetlag was described in terms of the entire journey with no distinction made between circadian disruption and travel fatigue. Management strategies revolved around needs for comfort and avoiding fatigue, and were mostly guided by somatic symptom cues, prior travel experiences, or the experiential advice from others. Our findings highlight the need for traveller involvement in co-designing evidence-based interventions for jetlag to enhance their transferability into the real world. Practitioner summaryQualitative findings highlighted jetlag as encapsulating the entire journey, and not limited to post-flight circadian disruptions during international travel. Jetlag management interventions need to address issues of circadian misalignment together with travel fatigue and in-flight discomfort through behavioural and nutritional strategies. Travel context and environmental factors such as airport facilities also influenced perceived jetlag severity.
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Affiliation(s)
- Su Fern Beh
- Sydney Pharmacy School, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
| | - Elisa Nicola Holdik
- The Brain and Mind Centre, The University of Sydney, Sydney, Australia
- Sleep Research Group, Charles Perkins Centre, The University of Sydney, Sydney, Australia
| | - Yu Sun Bin
- Sleep Research Group, Charles Perkins Centre, The University of Sydney, Sydney, Australia
- Northern Clinical School, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
| | - Janet M Y Cheung
- Sydney Pharmacy School, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
- Sleep Research Group, Charles Perkins Centre, The University of Sydney, Sydney, Australia
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Chan V, Wang L, Allman-Farinelli M. Efficacy of Functional Foods, Beverages, and Supplements Claiming to Alleviate Air Travel Symptoms: Systematic Review and Meta-Analysis. Nutrients 2021; 13:nu13030961. [PMID: 33809656 PMCID: PMC8002180 DOI: 10.3390/nu13030961] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 03/10/2021] [Accepted: 03/12/2021] [Indexed: 11/16/2022] Open
Abstract
Airline passengers experience a range of symptoms when travelling on long flights. This review evaluated the efficacy of functional foods, beverages, and supplements claiming to address the effects of air travel for healthy adults. Products were identified in a scoping review of electronic databases, search engines, and grey literature (March to August 2019). A systematic review of the efficacy of product ingredients was conducted using five electronic databases from inception to February 2021. Articles were screened, data extracted, and assessed for risk of bias by two researchers independently. Meta-analysis was performed. Of the 3842 studies identified, 23 met selection criteria: melatonin (n = 10), Pycnogenol (n = 4), various macronutrients (n = 2), caffeine (n = 2), Centella asiatica (n = 1), elderberry (n = 1), Echinacea (n = 1), fluid (n = 1), and Pinokinase (n = 1). Meta-analysis (random effects model) indicated melatonin reduced self-reported jetlag following eastbound (n = 5) and westbound (n = 4) flights: standard mean difference −0.76 (95% CI = −1.06 to −0.45, I2 0%, p < 0.00001) and −0.66 (95% CI = −1.07 to −0.26, I2 45%, p = 0.001), respectively. Pycnogenol also reduced edema scores (n = 3), standard mean −4.09 (95% CI = −6.44 to −1.74), I2 98%, p = 0.0006). Overall, 12 of 183 ingredients contained in 199 products had evidence to support claims.
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