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