Very polished game from start to finish. There are many levels, and each one is assembled in different ways, which keeps things interesting. In the end, all you need to do is wake up, and you can loop (replay the game) again by going back to sleep, really neat.
Having reusable platform boxes (echos) across different levels is also a smart design choice. Difficulty is subjective for everyone, but it's a fair challenge, no complaints here.
Overall, great work!