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