Burning the candle at both ends could wipe out the beneficial effects of exercise for silvers, new research suggests. But the findings are confusing. While they were true for those aged between 50 and 60, researchers at University College London found it did not apply to people in their 70s and older. The study showed cognitive function improved over 10 year in the former group if they engaged in “higher levels of physicial acivity” as well as getting 6 to 8 hours sleep. But despite exercising, those in the group who slept fewer than 6 hours a night over the same period experienced a more rapid decline. The research built on earlier studies showing physical activity benefits brain health and may help protect against conditions such as dementia and Parkinson’s disease.