Here is the full list of all 14 Melatonin achievements.
Finish a custom edited level
Collect all rings in the game
Collect all stars in the game
Perfect the tutorial
Get through the morning
Get through night 4
Get through night 3
Get through night 2
Get a perfect score in scored mode
Get a perfect score in hard mode
Get through night 1
Score 3 rings in a level
Score 3 stars in a level
Get all perfect scores