It studies how individuals change over time and that processes that create those changes. Basic importance of development psychology is study of life. Development refers to the changes over time in the body and in the thinking or other behavior of a person that are due both to biology and to experience.
In case of a fresher how long does it take to become an anesthesiologist varies to that of a Doctor and requires around twelve years. Four years for undergraduate studies, course including organic chemistry, physics, math, anatomy, biochemistry, and molecular chemistry and then four year of medical degree.
After medical school, he or she must complete a residency in anesthesiology (usually four years) until being able to practice independently. . In the US, it would take, at a minimum, 4 years of college, 4 years of medical school, a 1 year internship, and generally 3 years of residency to become an Anesthesiologist. (An RN needs 1 to 2 years after college to become a nurse  anesthetist.)   It takes 4 years of Undergraduate Study at a University of your  choice, 4 years at a Medical School of your choice, and about 2-4  years of Internship.