Reaction time (RT) tests are known as simple and sensitive cognitive tests. A drawback of existing RT tests is that they require the full attention of a test person which prohibits the measurement of cognitive functioning during daily routine tasks. In this contribution we present our first steps in designing and evaluating reaction time tests which can be operated throughout everyday life by means of wearable devices. In a feasibility study we induce changes in reaction times by applying cognitive load in 5 test subjects. We compare the obtained wearable reaction times with desktop-based reaction time tests. We show that relative changes in the mean duration and the variability of reaction times are similar for both desktop-based and wearable reaction time test. We conclude that wearable reaction time tests seems feasible to measure changes in reaction times and hence would allow the measurement of cognitive functioning throughout everyday life.