Bhagavad Gita, Chapter 18, Verse 39

That happiness which begins and results in self-delusion arising from sleep, indolence and miscomprehension, that is declared to be Tâmasika.

This lowest kind of happiness is described here as never actually clear, real confusion running from start to finish.

Krishna names sleep and negligence directly as its real source, not just its result. Nothing about this mode of happiness is shown as genuinely earned or understood.