What is a 'Z-Score'. A Z-score is a numerical measurement of a value's relationship to the mean in a group of values. If a Z-score is 0, it represents the score is identical to the mean score. Z-scores may also be positive or negative, with a positive value indicating the score is above the mean and a negative score indicating it is below the mean.
The pineal gland, also known as the pineal body, is an important endocrine gland that produces the hormone melatonin. Melatonin plays a key role in the sleep/wake cycle and the bodyâs response to sunlight. The pineal gland is a small, pinecone-shaped mass of glandular tissue about 1/3 of an inch (8 mm) long.
Melatonin is a hormone produced in the brain by the pineal gland from the amino acid tryptophan. The production and release of melatonin are stimulated by darkness and decreased by light, suggesting that melatonin is involved in circadian rhythm (the internal body clock) and regulation of diverse body functions.elatonin is a hormone produced in the brain by the pineal gland from the amino acid tryptophan. The production and release of melatonin are stimulated by darkness and decreased by light, suggesting that melatonin is involved in circadian rhythm (the internal body clock) and regulation of diverse body functions.