The pineal gland is part of the endocrine system and like the other endocrine glands; it is responsible for releasing hormones in the body. Similar to the other organs in the body, the pineal gland has specialized cells. The primary cells of the pineal gland are known as pinealocytes. Their function for the body is to release the hormone melatonin which plays an important role in several bodily functions throughout a person’s life.
The pineal gland is a pea-sized organ located in the brain, almost at the exact center, and was the last gland of the endocrine system to have its function discovered. For a long time, scientists believed that the gland had no function and that it was an organ similar to the appendix, which no longer serves a function in the body. This however was proven wrong in the 1960s when it was discovered that the pineal gland actually plays an important role and the pinealocyte cells of the gland are responsible for producing melatonin.
The production of melatonin happens in the pinealocytes and the hormone is secreted to the rest of the body through capillaries. The cells are important because melatonin is primarily responsible for regulating sleeping cycles. The melatonin production in the pinealocytes is suppressed by light and stimulated by darkness and is the reason why people feel tired when it gets dark out and wake up in the morning when the sun is out.
The production of melatonin by the pinealocytes will decrease and change with age. Children or young adults produce more of the hormone and its production occurs earlier in the late afternoon (between 6 and 7pm) while adults produce less melatonin and the production in an average adult may occur a few hours later than with children (between 8 and 9pm). This is partly responsible for many sleeping problems for adults as they no longer have the melatonin production that they once did when they were younger. Normal sleeping cycle and melatonin cycle can easily be disrupted by changes in routine, working late shifts, or by jet-lag.
In women, melatonin is also responsible for regulating menstrual cycles. The melatonin cycle will regulate when female reproduction hormones begin to be released and also when the release should stop.
In addition to the primary function of melatonin, the hormone is also linked to a variety of other functions in the body such as boosting the immune system, decreasing depression and anxiety, as well as heart, thyroid, adrenal gland, and temperature functions. Because of the links to these problems, melatonin supplements are available for use. The supplements are usually taken by those with sleeping disorders but there are a variety of other ailments that melatonin supplements are supposed to help. While there is little chance of toxicity with taking supplements, there is not enough evidence to support that taking melatonin supplements will help improve any conditions or that it is safe for long-term usage.