Mice and humans have the same photopigments in the same types of cells. How did they test this? They used mice, since mice are similar to humans in terms of genetics and behaviors. Scientists learned that circadian photoreception requires the eyes. Characteristics of Circadian Photoreception Each photoreceptor cell contains only one type, or color, of photopigment. Rods and cones contain photopigments, special pigments that change when they absorb light. In the nighttime, when there is little light, we use another type of photoreceptors, called rods. In the daytime, we use photoreceptors called cones. Photoreceptors are a special type of nerve cells in the eyes that respond to light. Normally, when you think of the eyes, you think about vision. Circadian photoreception is a part of the visual system, so it is related to processes happening in the eyes.
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The biological clock of the brain is in turn responsible for maintaining many circadian rhythms: mental, physical, and behavioral changes linked to the 24-h clock.
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So, circadian photoreception is how the biological clock of the brain, a special part of brain called the SCN, synchronizes its 24-h rhythm to the sunrise. Circadian means a rhythm which is close to 24-h. Photoreception means that a biological system is sensing light. Why are you active during the day and sleepy at night? This cycle happens due to a process called circadian photoreception, which is the way we synchronize the body’s internal, 24-h clock to the light and dark periods outside. Last, we examine ganglion cells, which are special cells in the eye that send information to the brain. We explore the key parts involved in circadian photoreception: photopigments, which are the pigments in the eye that change when they absorb light and are each found in their own cells. In this article, we discuss the characteristics of circadian photoreception and the scientists that helped us understand this process. Have you ever wondered why you are active during the day and sleepy at night? Why are some animals like owls and mice the opposite? A big reason for this is called circadian photoreception, which is the way we synchronize the body’s internal, 24-h clock to the light cycle outside.