Dissonance is a disrupting effect that results in the wearing down of magic when confronted with Sleepers.
A very essential part of the Lie is the inability of the Sleepers to cope with the higher truths of the Realms Supernal if confronted directly with them. If a sleeper bears witness to an act of supernal magic, Dissonance forces him to forget the incident as anything unusual. This can diminish the spell potency and even dispel an effect completely. It also increases the chance of triggering Paradox. For Sleepers, witnessing an act of Supernal magic results in a breaking point against Integrity.
Mages debate endlessly about why this is so. Ancient records have no references to any such effect before the end of the Times Before and the division of the worlds. It seems that human souls, cut off from the Supernal World and exiled to the Fallen World, cannot cope with the truth of magic. Something violently tries to keep their eyes shut. If they try to open their eyes, the Truth is too magnificent for them to grasp, and the Abyss offers truths that are contradicting and impossible. Vampires, werewolves, spirits, ghosts, and other strange beings can use their powers freely before the eyes of Sleepers. Mages theorize that Dissonance is a Sleeper's soul denying the truth of the Supernal World, as displayed by Awakened magic. Unable to separate the Truth of the Supernal from the Lie, the Sleeper flinches back, his own soul harmed by his exposure to the Abyss. The powers of other creatures, mages believe, originate in the Fallen World and do not stir the soul's memory of its fallen tragedy. In a sense, Dissonance is a near Awakening, but one that denies Awakening itself. Worse, the untruths of the Abyss know their own-Dissonance heals and feeds Gulmoth and Acamoth with Essence. The one mercy is that the human mind is able to suppress the memory of magic-otherwise, any Sleeper who saw magic would be attacked by the Abyss constantly, unable to move on.
This does mean the Sleeping Curse is fragile, however. The Abyss is, at its core, fundamentally untrue, and thus an understanding of the world that denies the Lie (however that is done) immunizes the Sleeper against the Abyss' falsehoods-they cannot understand the truth, but neither are they forced to accept lies. This is why any person with any degree of supernatural power, however minor, is a Sleepwalker.
- , p.298-299