Older people facing regular sleep disturbances may be close to finding a breakthrough after new research linked ageing with insomnia. An interesting Danish study revealed at the start of September that a natural deterioration in eye lenses may be partly to blame for their lack of rest. According to Line Kessel and associates at Glostrup Hospital in Copenhagen, researchers found that lenses lose their crystal-clear quality and become yellowish; this discoloration filters blue light and stops it reaching the image-gathering retina at the rear of the eye. Dr Kessel noted that this blue light is a portion of the visible light spectrum that regulates the body's 24-hour circadian rhythm, and also triggers the release of melatonin. This latter hormone governs the sleep-wake cycle. The expert explained: "From the age of ten, our lenses slowly become more and more yellow. So when you're a senior, you are getting very, very little blue light."