Sleeping Patterns Are Governed by Light

Your biological clock is not the only thing that reminds you to shut your eyes every 24 hours; a new study has found that it's actually light that governs your sleeping patterns.

Your eyes use light to reset your biological clock through a mechanism that is separate from your ability to see, researchers at Johns Hopkins University found.

Researchers genetically modified laboratory mice so that a particular set of retinal ganglion cells - the ones that received input from the rods and cones of the eyes and send information to your brain - no longer functioned. The mice were still able to use light to see normally, but had great dificulty synchronizing their circadian rhythms to light or dark cycles.

The findings suggest that people who have trouble sleeping or seasonal depression may be having a malfunction that is contributing to their inability to detect light, which in turn may adversely affect their biological clocks.

Nature