In a particular adventure, the air in the lower levels is poisoned, causing 1d6 poison damage every hour:
From Hidden Shrine of Tamoachan in Tales from the Yawning Portal (p. 61):
"A creature takes 3 (1d6) poison damage every hour it spends in the gas. The gas is light, so it accumulates closer to the ceiling."
If a party take a long rest in such an environment, how do you calculate the cumulative effects of the poison air damage over time in combination with the restorative effects of the long rest?
The rules for a long rest state (PHB, p. 186):
At the end of a long rest, a character regains all hit points.
Does this mean, RAW, the characters take 8d6 damage during the long rest, but then 'wake up' at full HP? If after the nth hour, they drop to 0 HP and start rolling Death Saves, if they save, and make it to 8 hours, they wake up with full HP?
It seems like it shouldn't work that way, but I can't find any suggestion in the books that it would be otherwise.