Researchers at Cardiff University believe sleeping in a bright room could help to prevent the onset of a serious eye disease in people with diabetes.

One in 10 diabetics is affected by retinopathy, which can cause severe visual impairment and can lead to blindness.

This is important research because diabetic retinopathy can be a devastating complication for people with diabetes

Suzanne Lucas, Diabetes UK

Retinopathy occurs when tiny blood vessels at the back of the eye burst or get blocked, damaging the retina.

If it is detected early it is treatable, either through changes in diet or laser surgery.

It has been suggested that the damage to the eye may be caused by a lack of oxygen to the retina.

Low oxygen

This is a particular problem for people with diabetes because they generally suffer from impaired blood flow which reduces the amount of oxygen pumped around the body.

It is also a particular problem at night. The eye uses much more oxygen to see when it is dark.

If the flow of oxygen is limited or reduced then there is a risk of damage.

Professor Neville Drasdo and colleagues believe that leaving the light on at night could reduce any strain on the eye and the risks of developing retinopathy.

In studies on seven patients with type 2 diabetes, they found that the light could pass through the eyelid and prevent the eye from adapting to night vision.

This helped to reduce the eye's demand for oxygen and the risks of damage.

Night light

Writing in The Lancet, Prof Drasdo said: "Since light transmission through closed lids is adequate to suppress dark adaptation, our findings strengthen the suggestion that diabetic patients might benefit from a modified cycle of night-time illumination during sleep to reduce oxygen consumption in the retina."

Suzanne Lucas, director of care at the charity Diabetes UK welcomed the findings but said further research is needed.

"This is important research because diabetic retinopathy can be a devastating complication for people with diabetes.

"However, the research is in its very early stages with a small number of participants. It is also difficult to know how this could be practically applied and how it would effect normal diabetes management.

"We look forward to seeing the results of similar research in the future."