All you have to do is stay away from the Ranch for 24 In-Game hours (24 minutes) and this achievement is yours! I would suggest that you start these 24 minutes just before 6 AM, and get Up All Night at the same time. Simply don't return to the Ranch until after Up All Night pops and you'll get this achievement too!
Here's my video for all achievements if you'd prefer. Skip to 6:08 for While You Were Away.