One of the hardest moments as a new parent was the night I couldn't console my son. It happened one random night but my wife took care of him while I slept....the following night it happened again...and it was "my turn".
He was only six months old at the time and traditionally a great sleeper. It was around midnight (only 20 min after I laid my own head down, of course) and he woke up with a weird cry. The crying was different than pain, hunger or fright...it was a cyclical cry/whine/whimper. It only took a few minutes for me to realize something was up...and this was not normal.
He was not alert or aware, but awake. Was he sleep-crying? I became really concerned when he wouldn't respond to my voice, clapping my hands, or any soothing actions. He didn't really "see" me when we looked at each other. I walked around with him, sat in a different room, even went outside...but nothing calmed him down. I grabbed bunny (a favorite toy that was in the laundry for the last few days), which helped a bit, but after an hour, he just "came out of it" and fell asleep...exhausted. I put him back in his crib and rubbed his belly for a few minutes while he fell asleep like nothing happened.
I immediately did an internet search, which will generally scare you even more, but found that many kids get these night-terrors. A combination of illness and lack of sleep can trigger this interruption in REM sleep. Additionally, over stimulation after it occurs, only makes it worse. He seriously was never "awake", just stuck between a few sleep stages. I never felt so helpless in my life.
Afterwords, as I shut my eyes, all I could hear is his cyclical/hysterical screaming and crying in my head. Wow...that was not in the "new parent brochure".
There are differing philosophies on this, some pick up, some let lie. The first and second nights we had no idea what it was, therefore we picked him up. We decided if it happens again, we'll just monitor him (since our presence didn't seem to help)...luckily it didn't come to that. Looking back, he did have a fever for a few days, was changing from 3 to
2 naps a day and picking him up and turning on lights were all
contributions to these episodes.
He's fine now.