Here is the full list of all 27 Dreamwalker: Never Fall Asleep achievements.
Complete 3 Hidden Object Puzzles with no more than 5 mistakes in each one.
Release Sandra from the Nightmare.
Complete all Hidden Object Puzzles without using a hint.
Finish any Hidden Object Puzzle in less than 30 seconds.
Collect all Postcards and Stamps.
Find 32 Dreamer's Sheep.
Finish all Minigames without skipping.
Finish all Meditation Minigames without skipping.
Record the murderer's confession.
Get to Allan's atelier.
Find the hard evidence.
Find 3 Hidden Objects in 3 seconds.
Escape the prison cell.
Break into the mayor's cabinet.
Read all the notes placed throughout the game.
Find 16 Dreamer's Sheep.
Find the book about the Nightmare.
Save Hellen from the car wreckage.
Escape the carriage.
Watch all the cutscenes from the first hour of the game.
Get into the Tower.
Find Sandra's diary.
Finish three Minigames in a row without skipping.
Confront Sandra's trauma.
Complete any Hidden Object Puzzle without using a hint.
Finish a Minigame in less than 1 minute.
Find your first Dreamer's Sheep.