Newton died in his sleep in London, England, on March 31, 1727, at the age 85. On the previous day, after suffering severe pain in his abdomen, Newton blacked out and never regained consciousness.
Towards the end of his life, digestion problems forced Newton to drastically change his diet and mobility. A founding father of modern physics, Newton never married and had few friends, leaving many to be worried about his mental and emotional stability.
Isaac Newton was buried in Westminster Abbey. After his death, his hair tested positive for mercury, most likely from his alchemist pursuits. Mercury poisoning is thought to be a potential cause for his eccentricity later in life.