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.
The pineal gland is a neuroendocrine organ located in the midline of the brain. Melatonin, thought to be the output hormone of the pineal gland, plays a central role in the co-ordination of circadian rhythms and the circadian system. Circadian rhythms are centrally co-ordinated and physiological, psychological and behavioural processes, which in humans follow approximately a 24- to 25-hour alternating cycle. In humans, circadian rhythms are genetically programmed to synchronise with night and day.