My Circadian Clock. The My circadian clock app is for use in research studies examining how diet, exercise, and sleep affect health. Our body contains circadian (circa – approximately and dian – day) or 24 h clocks that influences the timing of sleep, hunger, metabolism, and physical ability. Research studies run in different locations are trying to understand the interaction between “how much” and “when” we sleep, eat, or exercise for better health. You need an activation code from these resear