Isso soa como "A face da noite" de Julio Cortazar. Eu encontrei fazendo uma busca na web por " sci fi conto asteca cada um sonhando com o outro "(desde que eu tenho certeza que foram os astecas e não os maias que eram famosos por sacrifícios humanos) e encontraram esta página :
A man on a motorcycle has an accident. After he’s given an anesthetic at the hospital, he dreams he’s a Motecan Indian fleeing from Aztec warriors centuries ago in Mexico.
Você pode ler a matéria na íntegra on-line.
Aqui está o homem no hospital moderno (não um médico, mas vítima de um acidente de moto), sonhando em ser perseguido pelos astecas em busca de humanos para sacrificar:
They carried him to the radiography room, and twenty minutes later, with the already-damp sheet placed over his chest like a black tombstone, he moved to the operating room. Someone dressed in white, tall and thin, approached him and examined the radiography results. Feminine hands accommodated his head, and he perceived that they were moving him from one stretcher to another. The man in white approached him once more, smiling, with something that glinted in his right hand. He patted his cheek and gave a signal to someone standing behind.
It was a curious dream because it was full of smells and he never dreamed smells. First the smell of a swamp, since at the right of the road lay a marsh, quagmires from which no one ever returned. But the smell stopped, and in its place came a dark and complex fragrance like the night, through which he was fleeing the Aztecs. And it was so natural, he had to flee the Aztecs who were on a hunt for men, and his only chance was to hide himself in the densest part of the jungle, taking care not to separate himself from the narrow road that only they, the Motecas, knew.
E aqui está o final da história, onde o homem sendo sacrificado pelos astecas percebe que esta é a verdadeira realidade e o futuro com tecnologia estranha é o sonho:
With one last hope he parted his eyelids, groaning to wake up. For a second he thought he had achieved it, because once again he was immobile in his bed, safe from the swinging with his head propped up. But it smelled of death, and when he opened his eyes he saw the bloody figure of the high priest that came toward him with a stone knife in his hand. He was able to shut his eyelids once more, but now he know that he would not wake, that he was awake, that the marvelous dream had been the other, absurd like all dreams; a dream in which he had ridden the strange avenues of an astonishing city, with red and green lights that burned with neither flame nor smoke, with an enormous metal insect that buzzed beneath his legs. In the infinite lie of that dream they had also lifted him from the floor, someone had also cut him with a knife in his hand, with him lying face up, face up with his eyes shut in the midst of the fires.