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I am searching for a science fiction short story I read in an anthology obtained from the public library in Riverside, California around 1964.
It is written in the first person, and deals with a man who takes an illegal drug during an epidemic of the drug's use. People who have taken the drug display one common after-effect: when approached, they all say "You aren't real" or "This isn't real".
The man enters a shop and is instructed to lie down on a cot. He is given the drug. He goes to sleep. He wakes up. He leaves the shop. He lives the rest of his life. He dies.
He wakes up on the cot in the shop. He gets up and leaves. He lives a different life, full of joy, heartbreak, boredom - the sort of things that make up a typical human lifetime - grows old, dies . . .
And, of course, wakes up again on the same cot, in the same shop. This goes on and on. Sometimes he dies violently, other times of old age and/or illness, but always reawakens on the cot in the shop. Can anyone help me find this story?