When you reach the very first bed in the game before hacking the door to bring down the ladder, sleep 50 times for 24 hours each(move the left stick to the left once to choose 24 hours). I played on custom difficulty with everything set to easy so hunger and whatnot wouldn't bother me. You can track what day you are currently on in the top right of the screen. The achievement should unlock once you reach day 50, but mine was delayed about 20 minutes.
Here is a video if you need a visual guide. Credit: Trophy Germany. Note that the bed does not matter, it can be done at any bed in the game.