In which we try to catch some shut-eye.

 Not gonna add this to my current campaign but you can bet it'll be part of the NEXT one!

Per Xanthar's: 

Sleeping in light armor has no adverse effect on the wearer, but sleeping in medium or heavy armor makes it difficult to recover fully during a long rest.

When you finish a long rest during which you slept in medium or heavy armor, you regain only one quarter of your spent Hit Dice (minimum of one die). If you have any levels of exhaustion, the rest doesn’t reduce your exhaustion level.

OK.  So we'll use this.  Gotta skin outta that medium/heavy armor to get the full benefit of a long rest.  FWIW Elves don't sleep.  They trance, so no effect.  Game-wise it makes those late-night surprise attacks a little more troublesome.  As a player just make it the rule that if you're exhausted and/or have lost more than 1 HD of damage, you need to be comfy! 

So what if you DON'T get a long rest?  I'm a bit skint when it comes to allowing them, so this might be hard on my parties.  I'll need to be aware of this.  IF you go 24 hours without a long rest you need to make a CON check at DC 10 or take a level of exhaustion.  The DC increases by 5 every additional 24 hours.  Result:  going 24 hours is doable.  Making that first roll isn't bad.  But when you go 48 the DC is 15.  Fail THAT and you take a lvl of exhaustion so the NEXT roll (72 hours) is at DC 20 and -1.  Now you're in a death spiral.  Four days is at DC 25 and likely -2.

Some nice plot points can come out of this.  The elf in the party scurrying to find a suitable resting place (!?) for the fragile humans, etc.  Perhaps the exhaustion from lack of sleep doesn't lead to death but rather a coma-like state.  Out for 24 hours under any circumstances reduces exhaustion by 1 lvl, alowing the struggle to continue