in5

The human body is a complex system itself composed of complex systems; its state influences all aspects of our health, wellbeing including our cognitive to physical performance. In HCI most of us are not well versed in how this complex system works. The following paper proposes in5, a model to help make that physiology accessible for design. The model has two parts: (1) the MEECS dichotomies: five fundamental-to-life, volitional processes - move, eat, engage, cogitate, sleep - that are affected by parameters of quality, quantity, time and context, and (2) tuning: an approach to adjust the parameters of these dichotomies toward "dialing in" health, wellbeing, performance. The paper also offers examples for how this model can be explored for design research.