HALO Director, Professor Mark Tremblay was invited to deliver a presentation titled “Need for 24-hour movement behavior guidelines” at an invitation-only Wearable Devices & the 24-hour Activity Cycle Workshop at Stanford University in Palo Alto, California. The two day workshop brought experts from around the world together to discuss issues related to the measurement of physical activity, sedentary behaviour and sleep using wearable devices that collect a variety of different behavioural and biological signals. Methods for large data management and analysis were also discussed.