Can sunlight regulate circadian rhythm?

Yes, sunlight plays a crucial role in regulating the circadian rhythm. Andrew Huberman explains that neurons in the eye specifically respond to the quality and intensity of sunlight, particularly when the sun is low in the sky, such as during sunrise. This light exposure sets the body's circadian clock, which in turn helps regulate the body's overall biological functions across various organs and tissues. It is typically most effective to get sunlight exposure into your eyes soon after waking up to optimize the resetting of your circadian clock 1.

Furthermore, sunlight exposure is significantly more effective outdoors as the same conditions cannot be replicated through windows or from indoor lighting, which can filter out essential light wavelengths required for optimal physiological responses 1.