Jan is a psychiatrist and head of the research group Internet and Mental Health at the Department of Psychiatry and Psychotherapy of the Charité -University Medicine Berlin. Before he came to the Charité in 2009, he studied philosophy and medicine in Freiburg i. Br. and Hannover and then worked as a researcher at the Universities of Copenhagen and Oxford. In Copenhagen, he completed a PhD program on seasonal changes in the environment and their effect on neurotransmission. He described how environments that appear potentially hostile and dangerous are associated with changes in brain chemistry that can lead to more dogmatic behavior. From 2011 to 2014 he headed the neurochemistry research group of his department.

While being on a one-year paternity leave in 2014, an older case study he had written on "Twitter psychosis" appeared online and caused international attention of the media. He was stunned by this great need for information of the public (combined with a great potential to overreact of the mass media). So when he returned from paternity leave in 2015, he changed his research focus and founded a center for Internet and mental health for which he and his team received the Max Rubner Award - The Innovation Award For Trailblazers At the Charité.