Most organisms have a biological clock which has evolved as a consequence of the rotation of the earth around its axis. The biological clock generates rhythms of about 24 hours and adapts to daily changes in its environment. Light is the main synchronizer of the biological clock to the external light-dark cycle, and is detected by photoreceptors in the eye. To determine the effects of light on the biological clock in mice, in vivo electrophysiological recordings of neurons of the biological clock were performed. Mice were exposed to various wavelengths of light using monochromatic LEDs.
The spectrometer used in these experiments is an AvaSpec-2048. This spectrometer was used to determine the exact wavelength of light, including the bandwidth and to determine the light intensity and amount of photons per wavelength light. The effects of light on electrical activity of neurons in the biological clock were dependent on the wavelength, duration and intensity of light.