No, not your ordinary kid having screaming in the night.
The night terrors are humans infected with the night-stalker disease, once infected through the native bat like creatures begin to loose huge amounts of weight, until your basically skeleton-thin. further into the disease skin begins to pale and the hair begins to turn jet black. soon, over exposure to vitamin-c becomes fatal. despite your malnourishment further symptoms include development of super human abilities, and finally your sanity is stolen by primal instincts, and begin producing the night stalker disease yourself in your once inactive appendix, and soon people around you become infected.
Once an sufficient amount of hosts are infected to sustain a population a 'pack' form of order is formed and a depending on the biggest, strongest, most able
leader- Stays in the burrow and mates the healthiest females on breeding seasons, while the 'lesser' take whatever is left
raiders- The eldest males and females go about raiding and collecting whatever may of be use, make weapons out of objects used in there lives before, e.g a farmer using his shovel, a soldier using a firearm, a miner with a pickaxe, you get me right?
younglings- stay in the burrow until there old enough to become raiders
non-humans: mostly dogs, despite there master being infected, remain loyal to them. normally help the raiders
They are also very territorial over there food and water sources, and when aren't terrorising us, are battling each other