A BBC feature examines the toll that night-shift work takes on the body, exploring how repeatedly overriding the body's internal clock affects millions of shift workers, including nurses, paramedics, lorry drivers and factory staff. Scientists say the disruption is not simply a matter of tiredness but a collision with deep biological processes that occur during sleep, with growing evidence linking chronic shift work to heart attacks, strokes, cancer, mental illness and cognitive decline. Researchers are now investigating whether altering sleep patterns, rather than merely trying to sleep during the day, could reduce this harm.

The article highlights the brain's "glymphatic system", which clears waste products during sleep, and cites research by Professor Hugh Markus at the University of Cambridge, who analysed brain scans from over 40,000 people in the UK Biobank database. His team found that people with poorer waste-clearance function were significantly more likely to develop dementia later in life, suggesting disrupted sleep may have long-term neurological consequences. Scientists including Professor Russell Foster of Oxford University are also testing whether splitting sleep into two separate blocks, rather than one long daytime stretch, might better suit those working through the night.