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.
What is melatonin? Melatonin is produced by various tissues in the body, although the major source is the pineal gland in the brain. The production and release of melatonin from the pineal gland occurs with a clear daily (circadian) rhythm, with peak levels occurring at night. Melatonin is carried by the circulation from the brain to all areas of the body.