Evaluation of cognitive function is an important tool in clinical care. A novel method of cognitive monitoring is proposed, whereby subjects complete three sessions of the popular past-time Sudoku while EEG is recorded. Data epochs surrounding a correct solution are extracted and compared to a resting condition. Mean EEG amplitude in the alpha and theta bands are examined by means of the temporal spectral evolution method, and significant results include a desynchronization of alpha amplitude coinciding with an increase in theta amplitude prior to a correct solution in healthy adults. These results indicate that Sudoku may function as a light-touch, non-invasive and enjoyable means of monitoring for deteriorations in cognitive status.