The below linked article related to problem gaming at it highlights possible consequences of excessive time spent gaming including physical injuries, obesity, and mental heath issues.
The article also indicates that gamers can try the 20-20-20 rule: every 20 minutes, try to look at something 20 feet away for 20 seconds to reduce risk of eye strain. Which may not be something excessive gamers always remember to do.
The article also mentions the pool of mixed research that suggests "that there are some cognitive benefits to gaming, such as better control of one’s attention and improved spatial reasoning"