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