This learning activity examines the bidirectional relationship between sleep disturbance and mental health across depression, anxiety, PTSD, and bipolar disorder, equipping nurses to recognize sleep changes as an early clinical indicator of behavioral health risk. It reviews validated nursing assessment tools (ISI, AIS, STOP, PSQI, Epworth Sleepiness Scale), current evidence-based interventions including CBT-I and BBT-I, and updated 2025 VA/DoD and SCCM guideline recommendations on melatonin and sleep hygiene, while addressing special populations such as shift workers, older adults, postpartum patients, and adolescents. Framed within a trauma-informed, person-centered care model, the activity strengthens the clinical judgment nurses need to screen, educate, intervene, and refer appropriately when sleep disturbance signals or worsens a behavioral health concern.