Lex had gotten used to using the technique to disable his divination before he slept, but today, before this nap, he tried something different. Instead of trying to prevent vision, he focused on two key words: 'treasure' and 'system'.
He was hoping that, through the use of divination, he'd be able to get some clues. He was not depending on it entirely for answers, but it was worth a try. It was one of the reasons he wanted to wake up after only a couple of hours, lest he be completely drained when he woke.
But, as usual, things spiraled out of control. A part of him had expected as much, to be honest. Due to the flood of information, he entered a deep sleep and was unable to wake up naturally, or even through Mary's probing.
But, though the nap ended up being longer than anticipated, it did not go on for too long. Around his eighth hour sleeping, something 'clicked' and Lex suddenly woke up fully ready for a fight.