This achievement is rather insane. It requires you to, literally, spend 7 consecutive hours in the tent. The easiest way to do this, unless you really want to try to sleep with the headset on, is to get into the tent, place your headset on the floor or on a pillow, then go away for 7 hours.
Note 1: There is a bug which has allowed some people to get it to unlock by just lying down for a few minutes. Most are not so lucky.
Note 2: Prior to a recent update, this was almost impossible to get legitimately due to tracking bugs which would case you to gradually find yourself sliding out of the tent or teleported out. The 1.1 fix added a check point inside the tent for when tracking is lost, so by putting the headset on the floor it will constantly lose tracking but teleport you right back inside the tent without resetting the counter.