During the entire life of any human body, human growth hormone has a descending graph. In the beginning of the life, (about 1 to 2 years), the human growth hormone level is at its peak, that measure up to 2000 units. After puberty the high level decreases. At the age of about 25, human growth hormone again decreases and now it measures approximately 600 units.
Further as the human body grows, human growth hormone level decreases constantly up to 80-90 units every year till the age of 60. Almost all people look so nervous, exhausted and older.
If the levels of human growth hormone are higher in a person, it can lead to markedly healthier life, and as a result, such individuals tend to look less affected by the aging cycle. This links the human growth hormone and biological cycle of getting older.