Here is the full list of all 20 Back to Bed achievements. It takes around 3-4 hours to unlock all of the achievements on Windows.
Complete levels 1-30 in under 45 minutes.
Complete the game in nightmare mode.
Spend 10 minutes in one level.
Watch the credits to the end.
Complete the first dream world in nightmare mode.
Retry a single level 5 times.
Complete level 8 in the second dream world by having Bob take a shortcut.
Complete level 8 by moving only one apple.
Send 10 wheel clocks over the edge.
Allow Bob to be woken by a dog, an alarm clock, a whale train and a manhole.
Play the game at 13:37.
Open a door in nightmare mode.
Skip five cutscenes.
Get Bob safely to the end of the last level.
Walk through portals 30 times.
Scare five chess pieces.
Make Bob walk over the edge 10 times in a single level.
Help Bob through the first dream world.
Use the fast forward function for a combined 5 minutes.
Complete the first 3 levels to learn the basics of the game.