Method and apparatus for determining circadian input

Abstract

A method and apparatus for determining the circadian input of a light source includes selecting a circadian input to be measured based on an action spectrum corresponding to a wavelength sensitivity of photoreceptors for a circadian regulation system, where the circadian input is configured to stimulate a retinaldehyde photopigment, and for measuring spectral intensity across the action spectrum to determine the circadian input of the light source.

What is claimed is: 
     
         1 . A method, comprising:
 selecting a circadian input based on an action spectrum, wherein the action spectrum corresponds to a wavelength sensitivity of photoreceptors for a circadian regulation system, wherein the circadian input is configured to stimulate a retinaldehyde photopigment; and   measuring spectral intensity across the action spectrum to determine the circadian input of a light source.   
     
     
         2 . The method of  claim 1 , wherein the retinaldehyde photopigment comprises at least melanopsin. 
     
     
         3 . The method of  claim 1 , wherein the circadian input is correlated with a depression of serum melatonin levels in a mammal. 
     
     
         4 . The method of  claim 1 , wherein the circadian input has a peak intensity at an electromagnetic wavelength in the range of approximately 425 nanometers to approximately 505 nanometers. 
     
     
         5 . An apparatus, comprising:
 means for selecting a circadian input based on an action spectrum, wherein the action spectrum corresponds to a wavelength sensitivity of photoreceptors for a circadian regulation system, wherein the selected circadian input is configured to stimulate a retinaldehyde photopigment; and   means for measuring spectral intensity across the action spectrum to determine the circadian input of a light source.   
     
     
         6 . The apparatus of  claim 5 , wherein the retinaldehyde photopigment comprises at least melanopsin. 
     
     
         7 . The apparatus of  claim 5 , wherein the circadian input is correlated with a depression of serum melatonin levels in a mammal. 
     
     
         8 . The apparatus of  claim 5 , wherein the circadian input has a peak intensity at an electromagnetic wavelength in the range of approximately 425 nanometers to approximately 505 nanometers.