He might be testing for subclinical seizures. Those may not have symptoms and could happen during sleep. Heard this at an autism conference.

We did a three day EEG.

My son would sometimes have "staring spells." In addition, he had at least three febrile seizures. So, while we weren't sure if he was actually having an absence seizure, we decide to do an EEG.

Basically, they first begin by putting the electrodes on their head. My son is pretty good about things, but even he got a little upset by the process. Basically, they glue the electrodes to their head using a water soluble glue. Next, they hook all the electrodes up to wires. I swear, there are at least 20 wires maybe 30. Nevertheless, my son did a good job and stayed relatively calm.

As for the actual monitoring, they had a computer with a screen that would display the feedback from each of the electrodes. It's actually quite fascinating – I could tell when my son was simply closing his eyes or when he was actually asleep based on the feedback from the electrodes. (When they are asleep, you see periodic spikes that are consistent.) Additionally, we were given a keypad with a button to push if we thought he was having a seizure, so the doctors could look at that period of time with greater detail.

If you're able to look at the feedback in real time, you'll see a chart of all these different lines that indicate feedback from the electrodes. While this is occurring, the software that monitors the feedback from the electrodes will mark areas where they want a doctor to look at it. Don't be too concerned if you see a lot of areas where a "spike detected" or other variations. It's normal.

At the end of the EEG, the doctors pretty much came to the conclusion that my son was a "slightly higher" risk of seizure but not noticeably higher risk of seizure. In addition to doing an MRI to rule out any tumors, it was nice to know that we could at least stop worrying that his staring spells were absent seizures.

Also, the longer the EEG – the better. If a seizure is not detected in the first 24 hours, that's very good. If it's not detected in the next 24 hours - that's even better. And if they can't detect any seizures with an additional 24 hours (so 72 hours total) it's unlikely you have anything to worry about

My son had a staring spell where he stopped what he was doing and began to stare straight in front himself. I waved my hands in front of him, called his name then shook him lightly. There was no response. I called the ambulance and by the time they got to my house he snapped out of it. I set an appointment with neurologist at Boston Childrens Hospital and they determined to do a two day test where he wore eeg probes on his head which were attached to a machine. He stayed home from school because of this. When I took him back they downloaded the data from the machine onto their computer to discover the issue. The test was inconclusive for seizures, although he had a history of frebal seizures due to high temperatures

Please get it done. My son showed seizure activity in the tests YEARS before he had an actual seizure. The good news, with the onset of puberty came changes. No more seizures. Hopefully, that will be the case for many if not all of you. Blessings.

My son is having one done also..his glossy eye blank stare, with compulsive laughing, with aggressive out burst they say may be a seizer..
I've not had eeg done yet ,but the neurologist also asked for chromosome tests..that are suppose to be easier and accurate