Unravelling the cerebellum's role in sleep regulation: Prospects for precision sleep medicine.

The cerebellum, traditionally associated with motor coordination, is increasingly recognized as a regulator of non-motor functions-including cognition and emotions. However, its involvement in sleep regulation has been comparatively overlooked, mainly due to the historical exclusion of the cerebellum from electrophysiological and neuroimaging sleep research. Growing evidence now identifies the cerebellum as an active component of sleep mechanisms in both physiological and clinical contexts. Supporting findings include: (1) extensive cerebellar connectivity with major sleep-regulatory circuits; (2) state-dependent cerebellar neuronal activity synchronized with neocortical oscillations during NREM and REM sleep; (3) alterations in sleep patterns following cerebellar electrical stimulation; (4) differential expression of sleep-related genes in the cerebellum; (5) intrinsic cerebellar circadian rhythmicity; (6) structural and functional cerebellar changes in primary sleep disorders; and (7) high prevalence of sleep disturbances in cerebellar pathologies. Collectively, these data suggest that the cerebellum is deeply engaged in key sleep mechanisms, including the generation and modulation of sleep-related brain rhythms-such as sleep spindles-, sleep-dependent memory consolidation, and likely compensatory processes in sleep disruption. Nevertheless, fundamental mechanistic questions remain unresolved, particularly whether the cerebellum performs predictive modeling during sleep to support offline cognitive processing. Elucidating these computational functions and harnessing cerebellar neuroplasticity may advance our understanding of the intricate links between sleep, cognition, and emotion, while inspiring next-generation therapeutic approaches in sleep medicine.