It wasn't out of the ordinary for Xemnas to wake in the middle of dreams. They weren't really dreams, they were instances rewound and meshed together in odd sequences. He preferred not to classify his hallucinations as dreams, but much rather, his mind too busy to slow down when his body did.
Sometimes when he slept he saw nothing, and heard everything. Loud voices, maybe muffled conversations echoed in a black void behind his eyelids. He never recognized any of them, but found the assortment of sounds vaguely familiar. Though he could, he never spoke back. Very few of the voices called him by his name anyway.
Other dreams were more interesting. Senses never agreed with whatever was displayed in his memory. Once he recalled dreaming of an open field. The fresh scent of spring dew and budding flowers filled his nostrils, and the bitter taste of blood clung to the back of his throat. Strange. Someone brushed his back, and a twister ripped the earth from under his feet. It appeared to be the end, but he knew he had stirred midway. The sensation of something missing plagued him for the rest of his working day.
It also wasn't out of the ordinary for Xemnas' dreams to plague him. Some, to any normal someone, would be considered traumatizing. Xemnas only found them mildly unsettling. These sorts of dreams always began in the same place; a world he could not name next to someone he did not entirely know. Faces conveniently blurred and no amount of squinting could bring the outlines into focus. Their voices drowned when the world tilted and the sea crashed down from the sun. He always expected to drown with them, but when he was enveloped in the cascade he only saw bright light. Sometimes the light was bright enough to sting, others, heavy enough to burn the flesh from his bone. When he opened his eyes again, he would find himself staring into his own face. And wake mid-way.
More of his other nightmares were notorious for affecting him physically. These dreams were much harder to remember in the morning. They progressed in messy tangent lines, moving at such a high velocity that projected events crash into one another leaving cuts on his back, and sweat trickling from his forehead. When he woke it would leave his head spinning. Once, he was nauseous enough to vomit (though he didn't). He had hung over the toilet in confusion. With a climax comes a conclusion. Where was it?
It had to have been mid-way. He always felt something was missing.