Gfp - in regards to the sleep reduction, and I'm just spitballin' here, but I'd guess that patients with SA sleep longer than "normal" to make up for the disruptive sleep they get during the night.
So maybe - maybe - the sleep reduction caused by an ampakine would still result in a more restful / restorative sleep than a longer sleep duration but one disrupted by SA.
Also maybe over time the body would adjust to the presence of an ampakine in terms of sleep duration and the insomnia effect would grow smaller.