After read the concepts in the textbook about sleep disorders, I was surprised to learn that what my cousin often does during the night is not planks intended to scare me and my parents: what he does is he would suddenly awake during the sleep and sit straight up on his bed with his arms waving around, and mumbling as if someone is forcing him doing something, few seconds later he would landed heavily on bed again.
The eerie behavior of my cousin has a name called the "Night Terrors", which can happen in about 15% of younger children. Children who is having a night terror is often reported with their eyes wide open, screaming, perspiring and confused, these reports largely describe my cousin's late night actions except the kicking and griping he usually did. There were few times I waked him during his night terror and tried ask him what's going on, but he seems so tired to react to anything that he fell right back to sleep. To be honest, I was too scared to look at him on face, so I couldn't tell whether his eyes were open, but it seems that he can't recognize anyone, and he was not able to recall what happened the next morning.
I learned with relieve that the night terror is not a serious psychological disorder and it is normal among the children, with no need of special treatment but some good, regular sleep. It says that children will outgrow night terrors as they get older, but as I founded out personally, the night terror did not go away as my cousin growing up. I had a chance to share a same bedroom with my 17-year old cousin during a family trip. As the night goes deeper I heard someone talking angryly, then I felt someone is touching my ear. I turned my head around slowly:
Yes, it was my cousin, again...
But thanks to what I had learned about the night terror in psychology 1001, I'm no longer having nightmare about it.