the claim that Celsius causes brain fog is mostly false. Although, this article does a good job breaking down the way that Celsius can lead to brain fog, Celsius is not directly correlated with having brain fog. The article goes into how caffeine over time can effect peoples sleep and stress levels which then leads to brain fog, so they explain caffeine is problem not directly Celsius which they do site from a respectable government source the National library of Medicine and cite other information from Harvard. Overall this article has some truth to it and has evidence to back up what they are arguing, there main argument that Celsius causes brain fog is false.