A global effort to streamline how we talk about the 24-hour cycle of physical activity, sedentary behavior, and sleep.
By Ryan Falck, Karen Spruyt, Sjaan Gomersali, Kirk Erickson, Ester Cerin, Liye Zou, Antonio Palmeira, Teresa Liu-Ambrose
Have you ever thought about how your day is divided between moving, sitting, and snoozing? These three activities, also known as physical activity, sedentary behavior, and sleep, make up every moment of our 24-hour day and are interconnected. When you spend more time doing one, you automatically spend less time doing another. How we balance them matters. A poor night’s sleep can impact your motivation to move the next day, while regular exercise can help you sleep better at night.
The challenge: There hasn’t been a clear, consistent way to talk about this 24-hour activity cycle as a whole
In 2021, we recognized the lack of clear terminology for discussing these behaviors collectively. Researchers currently use a number of different terms to talk about these behaviors, including: movement behaviors, physical behaviors, or the 24-hour activity cycle. With so many names floating around, it’s hard to compare studies or communicate findings clearly. Not to mention, when we discuss behaviors across different languages, different terms might have different meanings. To address these challenges, the Around the Clock Terminology Consortium (ACT-C) was created.
The Around the Clock Terminology Consortium
Formed in September 2024, ACT-C is an international collaboration of researchers and organizations working to create a shared language for talking about the full 24-hour day, including how we move, sit, and sleep. The group brings together experts and societies from around the world, including:
What has ACT-C accomplished so far?
To get a clear picture of the problem, ACT-C conducted a massive review of nearly 1,000 scientific articles to map out how different researchers describe daily behaviors. We expect this review will be published in 2025.
Next, our team is launching a Delphi consensus process, a structured way to gather expert opinions and reach agreement. This process will bring together a diverse panel of experts from around the world to help shape consistent and inclusive terminology. We are currently recruiting expert panelists for our Delphi panel. As with the formation of our steering committee, we are adopting a multi-pronged approach to ensure a diverse and inclusive representation. We have recruited panelists from over 30 countries and 6 continents.
Why does this matter?
Clear and consistent terminology might sound like a small detail, but it’s a cornerstone of good science. When everyone speaks the same language, researchers can better share findings, build on each other’s work, and ultimately improve how we understand and promote healthy lifestyles.
Looking ahead
The ACT-C team is working hard to create an internationally-accepted framework for discussing the 24-hour cycle—from the moments we move, to when we sit, to when we sleep. By developing shared terminology, we can better study how these behaviors interact to improve our health and well-being.
You can follow the consortium’s progress, learn more about our team, and stay updated on results by visiting aroundtheclock.med.ubc.ca.