In 2018, the Times reported that members of the Tesla board had grown concerned about Musk’s use of the prescription sleep aid Ambien, which can cause hallucinations. The Wall Street Journal reported earlier this year that he uses ketamine, which has gained popularity both as a depression treatment and as a party drug, and several people familiar with his habits have confirmed this. Musk, who smoked pot on Joe Rogan’s podcast, prompting a NASA safety review of SpaceX, has, perhaps understandably, declined to comment on the reporting that he uses ketamine, but he has not disputed it. “Zombifying people with SSRIs for sure happens way too much,” he tweeted, referring to selective serotonin reuptake inhibitors, another category of depression treatment. “From what I’ve seen with friends, ketamine taken occasionally is a better option.” Associates suggested that Musk’s use has escalated in recent years, and that the drug, alongside his isolation and his increasingly embattled relationship with the press, might contribute to his tendency to make chaotic and impulsive statements and decisions. Amit Anand, a leading ketamine researcher, told me that it can contribute to unpredictable behavior.