People connect with others with similar experiences in social media. Knowing that other people feel the same way is very validating. However, too much social media engagement involving exchange of distressing information may result in psychological distress. 
Social media has become a huge virtual support group for many. Here, people provide each other emotional support. Usually, high amounts of received social support result in positive psychological outcomes. However, that is not always the case. While social media allows for provision of emotional support, this process of providing and receiving support by listening to each other’s distressing stories may have the opposite of the intended effect. This distress may be explained by the “pressure-cooker” effect. 
The “pressure-cooker” effect (Hobfoll, 1986; 2009) is observed when members of support networks, especially those at the centre (e.g., fully immersed in social media), also get the most exposure to distressing information. In social media, these information are shared rapidly, but are also shared mostly within the members of these online social groups. Information bounces back and forth, increasing one’s exposure to these information exponentially (imagine how a pressure cooker works).
The distress due to social media activity may also be explained by the stress-contagion effect (Riley & Eckenrode, 1986; Wilkins, 1974). This is observed when people carry the burden of a much wider social network in addition to their own. In times of emergencies and disasters, people may experience stress contagion when the knowledge of other people’s suffering negatively affect those who have not experienced them personally (Hobfoll et al., 1995; Kaniasty & Norris, 2004).
For both the “pressure-cooker” effect and the stress-contagion effect, the size of the social network is directly proportional to the level of psychological distress. In social media, the degree of engagement may also be directly proportional to the level of distress. Therefore, while being on social media during times of emergencies and disasters have benefits (e.g., information), too much engagement in these platforms may backfire and cause unintended, unnecessary distress.
References
Hobfoll, S. E., & London, P. (1986). The relationship of self-concept and social support to emotional distress among women during war. Journal of Social and Clinical Psychology, 4(2), 189-203.
Hobfoll, S. E. (2009). Social support: The movie. Journal of Social and Personal Relationships, 26(1), 93-101.
Kaniasty, K., & Norris, F. H. (2004). Social support in the aftermath of disasters, catastrophes, and acts of terrorism: Altruistic, overwhelmed, uncertain, antagonistic, and patriotic communities. Bioterrorism: Psychological and public health interventions, 3, 200-229.
Riley, D., & Eckenrode, J. (1986). Social ties: Subgroup differences in costs and benefits. Journal of Personality and social Psychology, 51(4), 770.

Wilkins, W . (1974). Social stress and illness in industrial society. In E. Gunderson & R. Rahe (Eds.), Life stress and illness (pp. 242-254). Springfield, IL: Charles C. Thomas.