The pineal gland or pineal body is a small endocrine gland about the size of a grain of rice and sits in the centre of the brain between the two hemispheres. It is shaped like a miniature pine cone, which is where its name is derived from. Its function was completely unknown until about 1970, and even today is not fully understood.
Sometimes known as the third eye, it features heavily in spiritual and esoteric knowledge. It has been thought to be the key to unlocking the connection to memory, spiritual worlds and the source of supernatural abilities. It is also philosophically said to be the “principle seat of the soul”.
The pineal gland has a far more developed eye-like resemblance in primitive animals such as frogs and some lizards. In humans it is able to sense the difference between light and dark by nerve connections to the part of the brain (optic chiasma) where images from the eyes are first processed.
In simple terms the pineal gland is the clock of the body, and by releasing the hormone melatonin it is able to regulate body functions that change with time. Melatonin release is increased by the pineal gland when a human is in the dark and decreased when they are in light. Other time related changes influenced by the pineal gland include the slowing of the body’s metabolic (biochemistry) activity at night, the cyclical nature of a woman’s menstrual periods, and the time at which puberty should commence, and possibly when menopause should occur.