Research Suggests Retina Is Body Clock

The daily shedding and regrowth of cells in the retina nerve of the eye may help control the sleep cycle and guide the body’s perception of the passage of time, researchers report.

In laboratory studies using retinas removed from the eyes of hamsters, scientists at the University of Virginia, Charlottesville, found that the cultured cells controlled the release of melatonin based on light levels.

Researchers Gianluca Tosinin and Michael Menaker report in a study to be published today in the journal Science that the retina cells, kept alive in culture dishes, produced melatonin in response to darkness and suppressed melatonin synthesis during periods of light.

Earlier studies have shown that in mammals a part of the brain called the suprachiasmatic nucleus triggers a similar rhythm of melatonin release from the pineal gland in the brain.

The new studies suggest that the changes in the retina is a parallel timing mechanism for the body.

The rise and fall of melatonin is thought to control the body’s sleep-wake cycle.