Paul Erdos famously swore by their productiveness.
From Wikipedia:
His colleague Alfréd Rényi said, "a mathematician is a machine for turning coffee into theorems",[31] and Erdős drank copious quantities. (This quotation is often attributed incorrectly to Erdős,[32] but Erdős himself ascribed it to Rényi.[33]) After 1971 he also took amphetamines, despite the concern of his friends, one of whom (Ron Graham) bet him $500 that he could not stop taking the drug for a month.[34] Erdős won the bet, but complained that during his abstinence mathematics had been set back by a month: "Before, when I looked at a piece of blank paper my mind was filled with ideas. Now all I see is a blank piece of paper." After he won the bet, he promptly resumed his amphetamine use.
From Wikipedia:
His colleague Alfréd Rényi said, "a mathematician is a machine for turning coffee into theorems",[31] and Erdős drank copious quantities. (This quotation is often attributed incorrectly to Erdős,[32] but Erdős himself ascribed it to Rényi.[33]) After 1971 he also took amphetamines, despite the concern of his friends, one of whom (Ron Graham) bet him $500 that he could not stop taking the drug for a month.[34] Erdős won the bet, but complained that during his abstinence mathematics had been set back by a month: "Before, when I looked at a piece of blank paper my mind was filled with ideas. Now all I see is a blank piece of paper." After he won the bet, he promptly resumed his amphetamine use.