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.
Allow Bob to be woken by a dog, an alarm clock, a whale train and a manhole.
Retry a single level 5 times.
Complete level 8 in the second dream world by having Bob take a shortcut.
Complete the game in nightmare mode.
Complete the first dream world in nightmare mode.
Spend 10 minutes in one level.
Make Bob walk over the edge 10 times in a single level.
Open a door in nightmare mode.
Complete levels 1-30 in under 45 minutes.
Send 10 wheel clocks over the edge.
Watch the credits to the end.
Walk through portals 30 times.
Skip five cutscenes.
Get Bob safely to the end of the last level.
Scare five chess pieces.
Help Bob through the first dream world.
Complete level 8 by moving only one apple.
Complete the first 3 levels to learn the basics of the game.
Use the fast forward function for a combined 5 minutes.