Human life expectancy has increased dramatically over the past two centuries, owing to advances in modern medicine, nutrition and hygiene. However, molecular mechanisms controlling ageing and lifespan have only recently started to emerge. Ageing coincides with changes in a multitude of physiological processes, including circadian rhythms and sleep. Conversely, recent discoveries have revealed the role of circadian rhythm disruption in the progression and acceleration of ageing. Thus, understanding the interconnection between circadian decline and ageing, as well as the consequences of circadian misalignment, is key to uncovering potential therapeutic approaches to target age-related pathologies. Here, we present an overview of the role of circadian clocks in ageing and age-related processes.