Here is the full list of all 29 Dream achievements.
Collect all the Dream bible pages.
Find the mess on floor one.
Play the first bar of 'Counting Sheep'.
Visit all the side dreams.
Finish Act Three's Nightmare.
Finish Act Three.
Finish Act Two.
Find a past project.
Finish Act Two's Nightmare.
Eat all the cupcakes.
Finish the graveyard puzzle in ten moves or less.
Epic support needed...
Show off your festive side.
Finish Act One's Nightmare.
Finish Act One.
Finish all four mazes without getting caught.
Find the memories of an old experiment.
Leave on all the lights before sleeping.