Main Sleep is a fundamental biological process that is essential for physical restoration, cognitive functioning and overall health. Increasing evidence underscores its association with ageing 4 , disease susceptibility 5 and longevity 6 . Both insufficient and excessive sleep duration have been linked to a wide range of adverse health outcomes, including cardiometabolic disease 7 , cognitive decline 8 and psychiatric disorders, such as late-life depression (LLD) 9 . Importantly, sleep is probably modifiable, making it a potential target for promoting healthy ageing and reducing the burden of age-related diseases across the lifespan. In parallel, the field of ageing research has seen rapid progress through the development of biological ageing clocks derived from imaging and multi-omics data, like magnetic resonance imaging (MRIBAG) 1 , 10 , plasma proteomics (ProtBAG) 2 and metabolomics (MetBAG) 3 .…