Answer:
Ian is experiecing a sleep terror.
Step-by-step explanation:
A sleep terror is a sleeping disorder that can affect a person of any age, and it is frecuently to appear in childhood. It is different from a nightmare because of the specific characteristics of it. For instance it is very hard for a person to wake up when experiencing a sleep terror, it is followed by sweating and heart aceleration. The episodes repeat often.
Other syntomps that would appear, are abrupt waking up with agitation and screaming.