Middle age

Middle age is the period of age beyond young adulthood but before the onset of old age. Though the exact range is disputed, most sources place middle adulthood between the ages of 45-65. This phase of life is marked by gradual physical, cognitive, and social changes in the individual as they age. 
Middle adulthood.
This time span can be referred to as 'middle age' and has been defined as the time between ages 45 and 65. Many changes may occur between young adulthood and this stage.
The body may slow down and the middle aged might become more sensitive to diet, substance abuse, stress, and rest. Chronic health problems can become an issue along with disability or disease. Approximately one centimeter of height may be lost per decade. Emotional responses and retrospection vary from person to person, for example, experiencing a sense of mortality, sadness, or loss are common emotions at this age.
Those in middle adulthood or middle age continue to develop relationships and adapt to the changes in relationships. These changes are highly evident in the maturing relationships between growing/grown children and aging parents. Community involvement is fairly typical of this stage of adulthood, as well as continued career development.
Physical characteristics.
Middle-aged adults may begin to show visible signs of aging. This process can be more rapid in women who have osteoporosis. Changes might occur in the nervous system. The ability to perform complex tasks remains intact. Women experience menopause in the years surrounding the age of 50, which ends natural fertility. Menopause can have many side effects. Men may also experience physical changes. Changes can occur to skin and other changes may include decline in physical fitness, including a reduction in aerobic performance and a decrease in maximal heart rate. These measurements are generalities and people may exhibit these changes at different rates and times.
The mortality rate can begin to increase from 45 and onwards, mainly due to health problems like heart problems, cancer, hypertension, and diabetes.
Still, the majority of middle-aged people in industrialized nations can expect to live into old age.
Cognitive characteristics.
Erik Erikson refers to this period of adulthood as the generativity-versus-stagnation this is the seventh out of eight stages of Erik Erikson stages. Persons in middle adulthood or middle age may have some cognitive loss. This loss usually remains unnoticeable because life experiences and strategies are developed to compensate for any decrease in mental abilities.
During this stage, we can see that adults strive to have things that will outlast them. When we are talking about this stage, the generativity means that one is making ones mark. This is where one is trying to make the world a better place.
Key characteristics of generativity:
Then we can see that stagnation means a failure to find a way to contribute. When people are in this part of the stage we can see that people can feel disconnected from the community and society. 
Key characteristics of stagnation: 
There when we can understand how to increase our generativity and make sure that we are not using stagnation we can become better and be more connected in cognitive ways.
Social and personality characteristics.
For some, marital satisfaction remains but other family relationships can be more difficult. Career satisfaction focuses more on inner satisfaction and contentedness and less on ambition and the desire to "advance". Even so, career changes often can occur. Middle adulthood or middle age can be a time when a person re-examines their life by taking stock, and evaluating their accomplishments. Morality may change and become more conscious. The perception that those in this stage of development of life undergo a "mid-life" crisis is largely false. This period in life is usually satisfying, tranquil. Personality characteristics remain stable throughout this period. The relationships in middle adulthood may continue to evolve into connections that are stable.