I.G. Mosyagin was born on 24 November 1966 in the village Goncharovskaya, Velsk District, Arkhangelsk Oblast. In 1989, he graduated Military Medicine Faculty of Gorky Medical Institute where he was granted with Honors Diploma. Then he was affiliated with the Northern Fleet. His positions were Deputy Head of the Medical Service of TK-208 heavy nuclear submarine cruiser of the 1^st Fleet of Nuclear Submarines (1989-1990), Head of the 90^th Crew of Heavy Submarine Cruisers (1990-1991), Squadron Doctor of the 338^th Minesweeper Squadron (1991-1993), Flagman Doctor of the 52^nd Brigade of Water Area Defense, and Senior Assistant of Head of the Medical Service of Belomorsk Navy Base (1994-2000). From 2000 to 2002, his service was at the Department of Military and Emergency Medicine of Northern State Medical University (Arkhangelsk) where he took the position of senior tutor. In 2002-2009, he headed the Department. In 2002, he defended his candidate of science dissertation “Psychophysiological characteristics of spine disorders in servicemen” and, in 2007, his MD dissertation “Psychophysiological adaptation patterns in navy specialists”. 

Since 2009, he heads Research Institute of Navy Medicine at Northern State Medical University and, since October 2012, he is at the head of the Medical Service of Navy General Headquarters of Russia. 

I.G. Mosyagin supervised six candidate of science dissertations on military men health care, which were attributed to the following specialties: 05.26.02 “Safety in Calamity Situations”, 19.00.02 “Psychophysiology”, and 19.00.05 “Social Psychology”. He authored 180 publications on military psychophysiology, psychology, and safety in calamity situations and 29 manuals and textbooks, including authorized federal-level tutorials: “Organization and Tactics of Navy Medical Service” (2007), “Calamity Psychology” (2010), and “Calamity Medicine” (2010, 2012).  

Since 2008, I.G. Mosyagin is a member of the Board of Arkhangelsk Branch of I.P. Physiological Society, of the editorial boards of the journals Voyenno-Meditsynskiy Zhurnal (Military Medical Journal) of the Ministry of Defense of the Russian Federation and Morskoy Sbornik (Marine Annals) of the Russian Navy. Since 2015, he is Editor-in-Chief of the theoretical and practical journal Morskaya Meditsyna (Marine Medicine).

In 2015, I.G. Mosyagin was appointed to the position of Chairman of the Marine Medicine Section of the Scientific Expert Council of Marine College under Government of the Russian Federation. He is a contributor to developing the Marine Doctrine of the Russian Federation for up to 2030. This document stipulates for the first time the basics of health care for people employed at the Navy. At present, he is involved in developing the Federal Law of the Russian Federation “On the Governmental Management of Marine Activities in the Russian Federation” and heads drawing-up of the Concept of Marine Medicine in the Russian Federation for up to 2030.