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