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