xAI cofounder is taking a step back to 'go founder mode on my health' after Lyme disease diagnosis

"Over time, the symptoms worsened, with workouts or certain foods leaving him exhausted for days, he said. "There was a week where I slept 12 hours a day and still couldn't recover," he added. After multiple rounds of testing, Yang said his doctor diagnosed him with Lyme disease, a condition that is "famously hard to diagnose." He said that he was surprised by the diagnosis, as he did not recall a tick bite."

""Likely I contracted Lyme a long time ago, but until I pushed myself hard building xAI and weakened my immune system, the symptoms weren't noticeable," he added. Despite the setback, Yang said he felt "lucky" to have caught the condition relatively early. He said discovering it now would allow him to "fix it so I can push myself even harder when I rebound.""

Greg Yang will move into an informal advisory role at xAI immediately to "go founder mode on my health." His symptoms began after an illness in early 2025, with lingering fatigue and a drop in energy and creativity weeks after he believed he had recovered. Symptoms worsened over time, with workouts or certain foods leaving him exhausted for days and a week where he slept 12 hours daily and still could not recover. After multiple rounds of testing, a doctor diagnosed Lyme disease, a condition famously hard to diagnose. Yang did not recall a tick bite and suspects he contracted it long ago. He said he felt lucky to have caught it relatively early and plans treatment to recover and return at full strength. Elon Musk responded wishing him well.

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