Seems similar to "He Who Shrank" - I didn't read the book though. https://en.wikipedia.org/wiki/He_Who_Shrank https://en.wikipedia.org/wiki/He_Who_Shrank ETA:

Seems similar to "He Who Shrank" - I didn't read the book though. https://en.wikipedia.org/wiki/He_Who_Shrank https://en.wikipedia.org/wiki/He_Who_Shrank ETA: Seems that was a popular story line from that time. Also seems similar to Inception, with the idea that diving into deeper dream levels makes time in those levels run slower than in the real world.