Link between reading news and deteriorating mental health?
There was a talk on this topic at the 2019 Society for Personality and Social Psychology (SPSP) conference. I haven't been able to find a published paper based on the study they presented, but the authors generally concluded that political engagement can be associated with significant mental, emotional, and social health costs.

Reference
Smith, Kevin; Hibbing, John; Hibbing, Matthew (2019). Friends, Relatives, Sanity and Health: The Psychological Costs of Politics. Presented at the annual conference of the Society for Personality and Social Psychology (SPSP). Portland, OR.
Description
Using a nationally representative sample this study investigates the impact of political engagement on the psychological health of the American electorate. Results suggest that among large numbers of Americans politics is linked to stress, depression, various compulsive behaviors and even thoughts of suicide.