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