Zeke immediately tried to calm himself. He suspected that his old illness had relapsed again.
The first few times he entered the simulations and encountered ones which closely mirrored the real world, he had not been able to differentiate whether he had returned to reality or was still trapped inside the system. As such, he had come up with an alternative way.
In the house he woke up in, he had placed something that was very personal to him. It was a letter that was personally written by him and there was no second person in the world who knew its content. Hence, every time he awoke, he would first check if the letter was still present. If it did, then it meant he had returned to reality because there was no way this little piece of detail would be copied into the simulator, and vice versa.
It had already become a routine by now. This time, too, as soon as he woke up, the first thing he did was to check if the letter was still present. And it did.