Danish researchers from the Glostrup Hospital in Copenhagen have suggested that the yellowing of the eye lens could be one of the reasons for sleeping problems among the elderly.
The researchers said that the eye lens slowly becomes yellow as we grow old and acts as a filter preventing blue portion of the spectrum light from reaching the retina.
The researchers added that this blue light was responsible for regulating the body's 24-hour circadian rhythm and also triggering the release of melatonin hormone that governed the sleep-wake cycle of the body.
"You need the blue light input to send a signal to the brain. From the age of 10, our lenses slowly become more and more yellow. So when you're a senior, you are getting very, very little blue light. I think the yellowing of the lenses might be one explanation why older people have poorer sleep", lead researcher Line Kessel said.