This release contains the R sample code for the research project entitled "Long-term impacts of heatwaves on accelerated ageing". This version has been archived on Zenodo to ensure the reproducibility of the analysis. Computational Environment The analysis was performed using the following environment: R Version: R version 4.3.1 (2023-06-16 ucrt) Platform: x86_64-w64-mingw32 (64-bit Windows) Key R Packages Used The following R packages are essential for running the code: lme4 & lmerTest (for mixed-effects modeling) dplyr & ggplot2 (for data manipulation and visualization) ipw (for calculating inverse probability weights) dlnm (for creating basis functions for non-linear models) emmeans (for post-hoc interaction analysis)