A recently published study in The Lancet Healthy Longevity has investigated how sleep time and physical activity can affect a person’s cognitive function over time. The researchers, from University College London, examined the cognitive function and sleep habits of 8,958 people aged 50 years and over in England over a period of 10 years. They found that those who engaged in more physical activity but slept less (less than 6 hours on average) had faster cognitive decline overall. This means that after 10 years, a more physically active person sleeping less than 6 hours had the same level, on average, as someone who slept more but engaged in less physical activity. It was found, however, that those who, in general, were more physically active, were linked to better cognitive function compared to those who were less physically active at the very beginning of the study (beginning of the 10-year period). But this changed over the 10-year period, with shorter sleepers experiencing a more rapid cognitive decline.
This more rapid cognitive decline was, however, only applicable to people in their 50s and 60s. On the other hand, older participants, aged 70 and over, still profited from all the benefits of exercise on cognition even if they slept less than 6 hours. There is already a lot of knowledge about the important beneficial effects of physical activity on cognitive decline. The results highlight that sleep should also be considered when thinking about leveraging the positive impact of physical activity on cognition.
