Lukasz Sandelewski, 36, died of a caffeine overdose.
He was a Polish migrant who lived and worked as a welder in the English city of Peterborough, Cambridgeshire, News Sky reported.
He was found dead after his mother became concerned and asked the neighbor to check on her son.
According to a coroner, his room was "very cluttered with lots of empty drinking vessels on the floor".
Cambridgeshire assistant coroner Sean Horstead noted: "It's unclear how or by what means the deceased consumed very significant levels of caffeine but caffeine toxicity is the cause of his death.
The welder had a blood caffeine concentration of 282 micrograms of caffeine per millilitre of blood (any level above 80 micrograms of caffeine per millilitre of blood can be deadly).