Working nights could lead to memory loss in middle aged and older adults as those working late have 79% higher rates of cognitive impairment, study finds

Working night shifts could impair memory by up to 79 per cent in middle-aged and older adults, a study suggests.

Previous research has established that shift work – which refers to any work schedule that occurs outside the traditional 9am to 5pm working hours – has significant health effects.

A team analysed data on 47,811 adults which included information on employment, work schedules and results of cognitive function tests. One in five participants reported having been exposed to some kind of shift work in their careers.

Those working night shifts in their current job had 79 per cent higher rates of cognitive impairment compared with those who did only day work. And those who had worked night shifts during their longest job had 53 per cent higher rates.

The authors said disruption to the circadian rhythm – our body clock – may be to blame. 

Previous research has established that shift work – which refers to any work schedule that occurs outside the traditional 9am to 5pm working hours – has significant health effects (Stock Image)

Writing in the journal Plos One, the team from York University in Canada said: ‘The findings suggest a potential link between shift work exposure and cognitive function impairment. We speculate that disruptive circadian stimuli may play a role in neurodegeneration contributing to cognitive impairment.’

Russell Foster, professor of circadian neuroscience at the University of Oxford, said the conclusion that night shift work increases the risk of cognitive impairment was important. 

He added: ‘Such findings agree with both laboratory-based and field studies – for example on long-haul airline pilots – that sleep and circadian rhythm disruption is linked to poorer health outcomes, including impaired emotional and cognitive responses.’

Previous research found night shift work was also ‘significantly associated’ with an irregular and fast heartbeat.

The study of 283,000 people in the UK suggested women and those who were not as physically active might be at most risk of atrial fibrillation. Night shift work was also linked to an increased risk of coronary heart disease.

Figures from the Office for National Statistics revealed the number of night shift workers in the UK has dropped in recent years, from 9.5million in 2016 to 8.7million in 2022. The data showed that last year, 15 per cent of night-time workers did so from home.