My daughter began having absence seizures at age 9 and has continued to this day with now all types of seizures. It is essential to determine what the brain is doing at these moments.
A competent neurologist will first seek to "induce" an absence seizure during an office visit with rapid, short breaths for 2 minutes (hyperventilation) as a preliminary guide. If this results in a seizure (I've repeatedly observed my daughter seize this way), then you have enough data for most any insurance to cover an outpatient EEG.
During this painless procedure, they use several tools to activate the brain and then have actual photos of electrical activity. Sometimes absence are not the only type of seizures happening, and that can be unknown until this step. Then appropriate medication can be prescribed.
These steps do not usually have any influence over any concomitant psychological issues so those must be dealt with separately. However, of all childhood diseases, seizure disorders have the highest correlation with mental health issues such as anxiety and depression so it's critical to have a good psych evaluation also and have the 2 docs work together on medication and treatment.
Advances in anti-convulsant medications have occurred over the course of my daughter's disease that have allowed her to have a full and fulfilling life.
As a side note, at the worst of my flashbacks of childhood abuse, I had very short losses of awareness of time. Reports from others said I didn't seem unaware of my surroundings as my daughter was during her absence seizures. That's just an anecdotal observation and obviously would vary by individual with traumatic flashbacks. And that loss of time doesn't occur anymore, even when I'm having emotional or mini-flashbacks recently after years of no flashbacks at all (due to the recent death of my father).