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.
You need four years of college followed by four years of medical school, one year as an intern and three or four years in an anestheiology residency program. In total -- that is 12 years (though you get paid as an intern and resident). Chemistry would probably be a good major. It depends on what route you want to go. If you want to go the Med School route, it will take 8-10 years before you are registered to practice as an Anesthesiologist. The other route to go is to become an Registered Nurse, get your Bachelor of Science in Nursing, then go through a Master's Degree program to become a Certified Registered Nurse Anesthetist (CRNA.)