Editorial: Criticality: a novel brain metric associated with sleep that may elucidate sleep's influence on adolescent depression.

Major Depressive Disorder (MDD) has been shown to have a bidirectional relationship with sleep. Adolescence is both the peak period of onset for MDD and a time of pronounced sleep disruption, yet the mechanisms linking disturbed sleep to depression risk remain poorly understood. We propose that brain criticality, an EEG measure of neural dynamics and information processing capacity, offers a novel putative mechanistic lens to understand this relationship. In adolescence, criticality may be perturbed by sleep disturbance through both a short-term failure of nightly restoration and long-term progressive shifts in the developing brain's baseline set point. We outline how depression-related deviations from criticality could reflect a shifted set point, altered drift, or failed reset, each predicting distinct clinical presentations. Because these metrics can be extracted from existing EEG data, they offer an immediately translatable tool for risk stratification and mechanism-targeted treatment in adolescent depression.