Your brain loses oxygen during the seizure. It starts getting bad after reaching 4 minutes.

Yes

I don’t know what levels are normal but my noctural seizures were put down to the fact that I stopped breathing multipal times while sleeping. After having a sleep test I was given a CPAP machine to use and with medication my nocturnal seizures have stopped. A video EEG and ECG pick up that my son had a low heart rate and thankfully after further investigation it was found to be ok. Don’t know if this of any help but my go to is if you have questions of this sort ask your doctor Keep well and have a great Christmas or what ever celebration your faith does at this time of year