[NoPie]

Even if it is, no one suggested that local hunters sleep every night in the forest. If they happen to sleep under the tree once in a year, it won't increase their risk of death significantly.

There could be another reason why sleeping in the forest was dangerous – e.g., poisonous snakes or dangerous animals etc. Also if the temperature drops at night and they didn't have enough clothing, they could get hypothermia and so on.