Hyperexcitable VTA-mPFC dopaminergic circuit disrupts sleep spindle and mediates sleep fragmentation after chronic social defeat stress.

Chronic social defeat stress causes sleep fragmentation by increasing VTA dopaminergic activity, reducing sleep spindle density and disrupting NREM sleep in mice.

• Why it matters: Understanding how chronic stress affects sleep is crucial because sleep disturbances are common in stress-related disorders, yet their neural mechanisms are not well understood.
• What they did: Researchers used a mouse model of chronic social defeat stress and found increased firing of VTA DA neurons, leading to excessive dopamine in the mPFC, which disrupted EEG spindles and NREM sleep stability. They blocked dopamine signaling or inhibited HCN channels in VTA neurons to reduce sleep fragmentation and restore spindle metrics.
• The result: The findings suggest that hyperactive VTA DA burst firing is a key circuit-level factor in stress-induced sleep disruption and highlight potential targets for restoring sleep stability in stress-related conditions.