The molecular mechanisms that regulate sleep-wake cycle in mammals remain a mystery. Our previous study based on mouse genetics showed that calcium/calmodulin-dependent protein kinase II (CaMKII), a protein kinase that is regulated by intracellular Ca2+, plays a critical role in sleep/wake regulation (Tatsuki, 2016). More recently, in vivo gene expression approaches using AAV-PHP.eB has demonstrated that (auto)phosphorylation of CaMKIIβ and its activation during wakefulness is critical for sleep induction (Tone, Ode, Zhang, 2021). Furthermore, we discovered that the CaMKIIβ plays a role not only in the sleep induction but also in sleep maintenance, depending on its multiple phosphorylation state. In this study, we focused on the multiple phosphorylation state of CaMKIIβ in the sleep-maintenance mode and investigated additional phosphorylations that can modulate the function of this mode. The results provide significant implications for understanding the further modes of CaMKIIβ following sleep induction and sleep maintenance, and for exploring the functional domains within the molecule that are crucial for each mode.