In the present chapter we focus on time lags in panel studies investigating psychosocial factors and stressor-strain relationships. First, a framework of theoretical reasons for choosing specific time lags is provided, which is based on the work by Frese and Zapf (Methodological issues in the study of work stress: objective vs. subjective measurement of work stress and the question of longitudinal studies. In: Cooper CL, Payne R (eds) Causes, coping and consequences of stress at work. Wiley, Chichester, pp 375-411, 1988). Although this theoretical framework provides a clear rationale for time intervals, researchers are frequently mistaken using it to derive appropriate time lags. Second, an overview of other theoretical, methodological, and practical reasons, found in the literature, is provided. Reasons for choosing time lags are categorized as related to the construct, operationalizations, mechanisms, method, epistemology, or to the researcher. We advocate that elaborating on this topic in research papers is crucial in order to expand knowledge on the effects of time on stressor-strain relationships. Third, we suggest a much-needed taxonomy on different time lags. We advocate the use of the terms immediate, short-term, mid-term, meso-term, long-term, and grand-term stress-reactions in order to describe time lags used in different studies in a more nuanced way. Fourth, we apply both the overview of arguments for choosing time lags and the taxonomy on lengths of time lags to systematically review 16 panel studies from the Asia Pacific region, published in high-ranked journals. Case studies of six selected studies are provided and we conclude that studies in the Asia Pacific share both the strengths and the weaknesses of the literature worldwide. Applying the taxonomies and overviews in this chapter will help researchers to justify choices of shorter and longer time lags.