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 secreted by the pineal gland is an important part of the bodyâs circadian timing system and can synchronise daily rhythms (see the articles on jet lag and circadian rhythm sleep disorders).he pineal gland is situated in the middle of the human brain and is the major site of the bodyâs melatonin production. Alternative names for the pineal gland Pineal body; epiphysis cerebri; epiphysis.