VIMAD · Variations In Motivation Across the Day - Understanding the How and Why of Daily Fluctuations

Life on earth has evolved in synchrony with the day-night cycle. Most species, from single-cell plants to humans, have a circadian system that operates as a pacemaker, modulating a multitude of biological processes across the 24h period. Given the ubiquitous involvement of the circadian system in our physiology, it is not surprising that motivation and related neural systems such as dopamine also vary across the day, but with large variation between individuals. Time-of-day is increasingly being utilised to strengthen treatment effects and facilitate behavioural change. However, we still lack fundamental mechanistic knowledge for establishing more effective and widespread therapeutic applications in mental health care as well as in daily life. Hence, there is a need to more fully understand the circadian clock of motivation and drive. The objective is, first, to predict “when” (i.e., at which time of day) drive and motivation are heightened and blunted, and second, to scrutinise the underlying cognitive and neural mechanisms. Specifically, in phase 1, I plan to conduct a large-scale field study using a mobile application to quantify fluctuations in motivation to engage in daily-life behaviours and cognitive mechanisms including incentive motivation, reinforcement-learning, and cognitive flexibility. Then, in phase 2, I will use this knowledge to probe the role of dopamine in time-of-day effects of motivation by pharmacologically modulating dopamine at different times of day in a subset of the participants from phase 1. The combination of field research and basic experimental research will provide unique and clarifying knowledge of how and why motivation fluctuates both within and between individuals. Given the significant role of motivation in the healthy and sick brain, the results will provide novel valuable insights for the society at large.