A global consensus on terminology to discuss the 24-hour cycle of physical activity, sedentary behaviour, and sleep.

What is the Around the Clock Terminology Consortium?

Physical activity, sedentary behavior, and sleep occupy most of the 24-hour cycle and are associated with a multitude of health outcomes. As this field of research rapidly increases, a key question emerges: what should we collectively call these behaviors? In September 2024, we established the Around the Clock Terminology Consortium (ACT-C) – an internationally representative group of researchers and key interest-holder organizations to develop a consensus in terminology for the 24-hour cycle of physical activity, sedentary behavior, and sleep (https://aroundtheclock.med.ubc.ca/team/).

Why do we need a consensus?

There is a looming “24-hour Babel”. In 2021, we highlighted that there were at least five separate terms used by researchers when referring to physical activity, sedentary behavior, and sleep collectively (e.g., movement behaviors, physical behaviors, or the 24-hour activity cycle) (https://bjsm.bmj.com/content/56/7/367.long). As more scientists enter this field, the terminology is becoming increasingly inconsistent and confusing. The time is now to develop a consensus.

Achieving consensus the right way

However, consensus statements are prone to bias (https://bjsm.bmj.com/content/bjsports/56/6/306.full.pdf). For example, they are often male dominated, rely on a narrow definition of ‘expert’, lack representation from developing and lower income countries, and often do not conduct a review of the literature to identify the knowledge gaps. The lack of consideration for equity, diversity, and inclusion in previous consensus-building projects motivated ACT-C to pursue an inclusive, representative, and international consensus regarding terminology for physical activity, sedentary behavior, and sleep (See Figure 1).

Current progress

We have partnered with 12 different national and international scientific interest-holding societies, including: 1) International Society of Physical Activity and Health (https://ispah.tecology-hosting.co); 2) International Society of Behavioral Nutrition and Physical Activity (https://isbnpa.org); 3) World Sleep Society (https://worldsleepsociety.org); and 4) International Society for the Measurement of Physical Behavior (https://ismpb.org), among others. As a means of ensuring that we have a clear identification of the knowledge gaps, we have conducted a 979-article scoping review which examines the current terminology used to describe physical activity, sedentary behavior, and sleep over the 24-hour day. We aim to publish this review in 2025.

Next steps

As we analyze the data from the scoping review, we are now conducting our Delphi consensus which has recently been approved by the University of British Columbia’s Behavioral Research Ethics Board (H25-02045) in August 2025. We are currently recruiting expert panelists for our Delphi panel, and as with the formation of our steering committee, we are adopting a multi-pronged approach to ensure a diverse and inclusive representation. Our Delphi panel survey questions will be informed by the results of our scoping review.      

Summary

We have outlined our progress and plans to address the current lack of clear terminology for discussing the 24-hour day through an inclusive, international, and systematic process. ACT-C will establish internationally agreed-upon terminology for discussing the 24-hour cycle of physical activity, sedentary behavior, and sleep. For more information about our ongoing project, news, and results, please visit our website: https://aroundtheclock.med.ubc.ca.

Messages à emporter

• Clear, concise, and consistent language is fundamental for effective international scientific communication.
• The Around the Clock Terminology Consortium is dedicated to developing clear terminology for discussing the 24-hour cycle of physical activity, sedentary behavior, and sleep
• We are currently conducting a consensus to achieve internationally agreed upon terminology for the 24-hour day

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Authorship, Declarations, Affiliations, Keywords 

• Titles, first name, last names & numbered affiliations (separate with semi-colon) 

Title (e.g. Dr)	First name	Last name	Numbered affiliation	Competing interests (if none, please say “I have no relevant competing interests to declare”)
Dr	Ryan	Falck	1	I have no relevant competing interests to declare
Dr	Sjaan	Gomersall	2	I have no relevant competing interests to declare
Dr	Jasper	Schipperijn	3	I have no relevant competing interests to declare
Dr	Kirk	Erickson	4	I have no relevant competing interests to declare
Dr	Ester	Cerin	5	I have no relevant competing interests to declare
Dr	Liye	Zou	6	I have no relevant competing interests to declare
Dr	Ashleigh	Smith	7	I have no relevant competing interests to declare
Dr	Francisco	Ortega	8	I have no relevant competing interests to declare
Dr	Jennifer	Davis	9	I have no relevant competing interests to declare
Dr	Jannique	Van Uffelen	10	I have no relevant competing interests to declare
Dr	António	Palmeira	11	I have no relevant competing interests to declare
Dr	Michelle	Voss	12	I have no relevant competing interests to declare
Dr	David	Dunstan	13	I have no relevant competing interests to declare
Dr	Linda	Li	14	I have no relevant competing interests to declare
Dr	Jairo	Migueles	15	I have no relevant competing interests to declare
Dr	Nucharapon	Liangruenrom	16	I have no relevant competing interests to declare
Dr	Guilherme Moraes	Balbim	17	I have no relevant competing interests to declare
Dr	Jennifer	Tomasone	18	I have no relevant competing interests to declare
Dr	Matthew	Ahmadi	19	I have no relevant competing interests to declare
Dr	Karen	Spruyt	20	I have no relevant competing interests to declare
Dr	Frank Hookin	Fu	21	I have no relevant competing interests to declare
Dr	Lora	Giangregorio	22	I have no relevant competing interests to declare
Dr	Zhaowei	Kong	23	I have no relevant competing interests to declare
Dr	Jean-Philippe	Chaput	24	I have no relevant competing interests to declare
Dr	Miao	Miao	25	I have no relevant competing interests to declare
Dr	Natan	Feter	26	I have no relevant competing interests to declare
Ms	Keerthana	Swaminathan	27	I have no relevant competing interests to declare
Dr	Robert	Schinke	28	I have no relevant competing interests to declare
Dr	Yiqun	Gan	29	I have no relevant competing interests to declare
Dr	Shigeru	Inoue	30	I have no relevant competing interests to declare
Ms	Varadyini	Gorhe	31	I have no relevant competing interests to declare
Dr	Takumi	Abe	32	I have no relevant competing interests to declare
Ms	Maurelle	D’Sa	33	I have no relevant competing interests to declare
Dr	Yu-Kai	Chang	34	I have no relevant competing interests to declare
Dr	Amy Shirong	Lu	35	I have no relevant competing interests to declare
Dr	David	Lubans	36	I have no relevant competing interests to declare
Dr	Åsa	Tornberg	37	I have no relevant competing interests to declare
Dr	Teresa	Liu-Ambrose	38	I have no relevant competing interests to declare

• Numbered affiliations (separate with semi-colon): 

Number	Affiliation
1	University of British Columbia, Faculty of Medicine, School of Biomedical Engineering, Centre for Aging SMART at the Vancouver Coastal Health Research Institute, Vancouver, BC, Canada
2	The University of Queensland, School of Human Movement and Nutrition Sciences, Health and Wellbeing Centre for Research Innovation, Brisbane, QLD, Australia
3	University of Southern Denmark, Department of Sports Science and Clinical Biomechanics, Odense, Denmark
4	AdventHealth Research Institute, Neuroscience Institute, Orlando, FL, United States of America
5	Australian Catholic University-Melbourne Campus, Mary Mackillop Institute for Health Research, Behaviour, Environment and Cognition Research Program, Melbourne, VIC, Australia School of Public Health, The University of Hong Kong, Hong Kong SAR, China
6	Body-Brain-Mind Laboratory, Shenzhen University, School of Psychology, Shenzhen, Guangdong Province, China
7	University of South Australia, Alliance for Research in Exercise, Nutrition and Activity (ARENA) Research Centre, Adelaide, SA, Australia
8	University of Granada, Department of Physical Education and Sports, Faculty of Sport Sciences, Sport and Health University Research Institute (iMUDS); and CIBEROBN Physiopathology of Obesity and Nutrition; Granada, Spain
9	University of British Columbia-Okangan Campus, Faculty of Management, Applied Health Economics Laboratory, Kelowna, BC, Canada
10	KU Leuven, Department of Movement Sciences, Physical Activity, Sports & Health Research Group, Leuven, Belgium & Leuven Brain Institute , KU Leuven, Leuven, Belgium
11	CIDEFES, Universidade Lusófona, Lisbon, Portugal  CIFI2D, Universidade do Porto, Porto, Portugal
12	The University of Iowa, Iowa Neuroscience Institute, Department of Psychological and Brain Sciences, Iowa City, IA, United States of America
13	Institute for Physical Activity and Nutrition, Deakin University, Burwood, Australia Baker Heart and Diabetes Institute, Melbourne, Australia
14	University of British Columbia, Faculty of Medicine, Department of Physical Therapy, Arthritis Research Centre, Vancouver, BC, Canada
15	University of Granada, Department of Physical Education and Sports, Faculty of Sports Sciences, Sport and Health University Research institute (iMUDS), Granada, Spain
16	Mahidol University, Institute for Population and Social Research, Salaya, Thailand
17	University of British Columbia, Faculty of Medicine, Department of Physical Therapy, Aging, Mobility, and Cognitive Health Laboratory, Centre for Aging SMART at Vancouver Coastal Health Research Institute, Vancouver, BC, Canada
18	Queen’s University, School of Kinesiology and Health Studies, Revved Up Group, Kingston, ON, Canada
19	Mackenzie Wearables Research Hub, Charles Perkins Centre and School of Health Sciences, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
20	Université de Paris, INSERM, NeuroDiderot, Paris, France
21	Hong Kong Baptist University, Faculty of Arts and Social Sciences, Department of Sport, Physical Education and Health, Dr. Stephen Hui Research Centre for Physical Recreation and Wellness, Hong Kong
22	University of Waterloo, ​Department​​​ of Kinesiology and Health Sciences, ​​Waterloo, ON, Canada
23	University of Macau, Faculty of Education, Macau, China
24	Healthy Active Living and Obesity Research Group, Children’s Hospital of Eastern Ontario Research Institute, and Department of Pediatrics, University of Ottawa, Ottawa, ON, Canada
25	Peking University, School of Health Humanities, Department of Medical Psychology, Beijing, China
26	Federal University of Rio Grande d​o​​​ Sul, ​School of Medicine, ​​​Graduate Program in Epidemiology, ​     ​Porto Alegre, RS, Brazil
27	​​The Performance Doctor, Chennai, India, INSPA Sport Psychologist’ Association, Manipal Academy of Higher Education, Manipal, Karnataka, India, University of Staffordshire, U.K​​​
28	Laurentian University, Faculty of Education and Health, School of Kinesiology and Health Sciences, Sudbury, ON, Canada
29	Peking University, School of Psychological and Cognitive Sciences, Beijing, China
30	Tokyo Medical University, Department of Preventive Medicine and Public Health, Tokyo, Japan
31	​​​MindFirst Performance Psychology, Pune, India, INSPA Sport Psychologists’ Association ​​
32	School of Commerce, Meiji University, Tokyo, Japan
33	Department of Social Work and Wellbeing, Faculty of Health, Social Care and Medicine, Edge Hill University, Ormskirk, Lancashire, UK
34	National Taiwan Normal University, Department of Physical Education and Sport Sciences, Taipei, Taiwan
35	Northeastern University, Department of Communication Studies, College of Arts, Media, and Design, Department of Public Health & Health Sciences, Bouvé College of Health Sciences, Health Technology Lab, Boston, MA, United States of America
36	Centre for Active Living and Learning, College of Human and Social Futures, University of Newcastle, Callaghan, New South Wales, Australia Hunter Medical Research Institute, New Lambton Heights, New South Wales, Australia Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
37	Lund University, Faculty of Medicine, Department of Health Sciences, Sweden
38	University of British Columbia, Faculty of Medicine, Department of Physical Therapy, Aging, Mobility, and Cognitive Health Laboratory, Centre for Aging SMART at Vancouver Coastal Health Research Institute, Vancouver, BC, Canada