The pineal gland is a part of the endocrine system and has an important effect on the body. But what is it, where is located, and exactly what does it do?
The pineal gland is a very small gland that is shaped like a pine cone. It is about one centimetre long and it is located between the two hemispheres of the brain and above the third ventricle of the spinal column. The pineal gland is made up of pinealocytes and glial cells. It is an endocrine gland that secretes melatonin.
The primary role of the pineal gland is to secrete melatonin. Melatonin is a derivative of the amino acid tryptophan, from which serotonin; the precursor of melatonin is derived. This hormone controls various body rhythms, in particular, the internal body clock and sleeping and waking patterns.
The pineal gland works in accordance with circadian rhythms. In times of darkness, more melatonin is produced and released. In daylight, melatonin production is greatly reduced. When night falls, melatonin is released, making a person feel sleepy. When dawn comes, the production of melatonin stops, helping people to feel wakeful and alert. Not only has research shown that melatonin regulates a person’s sleeping patterns, it may also regulate the hormonal changes that bring about sexual maturation.
The production of melatonin by the pineal gland is influenced both by the time of day and also by age. Children under 7 years of age have much higher levels of melatonin. Adolescents have lower levels and adults even lower levels. It is thought that melatonin stops the child’s body from undergoing sexual maturation. This is supported by the fact that sex hormones such as luteotropin (that plays a role in the development of sexual organs), only emerge when melatonin levels decline.