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.
Complete the game in nightmare mode.
Send 10 wheel clocks over the edge.
Complete the first dream world in nightmare mode.
Skip five cutscenes.
Open a door in nightmare mode.
Watch the credits to the end.
Get Bob safely to the end of the last level.
Walk through portals 30 times.
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.
Use the fast forward function for a combined 5 minutes.
Scare five chess pieces.
Spend 10 minutes in one level.
Complete level 8 by moving only one apple.
Retry a single level 5 times.
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.