All of us worry about losing our mental capacities as we grow older – but there’s a very simple technique we can adopt that will help keep us sharp, researchers have discovered this week.

They have found that our exposure to bright light can help ward off dementia.  For people who already have early stages of the disease, bright lighting can slow its progress by 5 per cent, which can mean the difference between living at home and having to move to a care centre.

Researchers from the Netherlands Institute for Neuroscience have found that cognitive decline is associated with poor sleep patterns, and people with dementia often sleep during the day and spend the night awake.

By increasing the level of light during the day, they discovered that a sufferer’s circadian cycle is normalized, slowing the progress of the disease.

They tested the theory on 189 residents in a care home, and installed bright lighting, which stayed on between 9am and 6pm every day, and their progress was compared with those whose lighting was not improved.

The good effects of brighter lighting was also amplified by using the natural supplement, melatonin, which is regularly taken in the US as a way of warding off jet lag after a long flight.  The supplement is banned in the UK.

Although those who were also given melatonin saw the best results in terms of the progress of their dementia, they were more withdrawn and had worse moods than those who were just exposed to brighter lighting.

Overall, the light therapy reduced cognitive deterioration by 5 per cent, and depression by 19 per cent, results that match powerful dementia drugs such as Aricept.

It’s thought that light therapy could benefit Huntingdon’s and Parkinson’s sufferers, diseases that are also associated with a disturbed circadian cycle.

(Source: Journal of the American Medical Association, 2008; 299: 2642-55).