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Some, including Rick Strassman, have suggested that the third eye is in fact the partially dormant pineal gland, which resides between the two hemispheres of the brain. This concept is supported by the pinealocytes, one type of cells within the pineal gland, having a strong resemblance to the photoreceptors of the eye. Additionally, the pineal gland is said to excrete dimethyltryptamine (DMT)[citation needed], which induces dreams, near-death experiences, meditation, or hallucinations. Various types of lower vertebrates, such as reptiles and amphibians, can actually sense light via a third parietal eye—a structure associated with the pineal gland—which serves to regulate their circadian rhythms.
The pineal gland produces the hormone melatonin, which has a role in regulating the body's circadian rhythm to the daily light/dark cycle and also assists with the immune system[citation needed]. Because of all the above, the pineal gland has become for some the subject of speculation about its origin as a physical third eye.
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