Would an in-lab overnight assessment for sleep apnea also identify seizures during sleep, if they were occurring?

Yes: Most seizures would be picked up on the eeg leads of the equipment and the techs and docs are trained to recognize them on the polysomnogram readout.There is always a possibility that no seizure activity may show on a given night or that the eeg leads might not pick it up as well as a full seizure montage system.

sleep study: An overnight supervised sleep study would monitor all vital signs including oxygen levels and would make note of any seizures as well as brain activity.