Researchers from the Perelman School of Medicine at the University of Pennsylvania in Philadelphia report that a night without sleep can alter certain brain connections linked to mood. The findings appeared in a British medical journal published by Medical Express.
The study focuses on the interaction between the amygdala, a key emotion-processing region, and the anterior cingulate cortex, an area involved in emotional regulation. Scientists observed that changes in this neural link correlated with mood shifts, occurring in both individuals with depression and those without this condition.
The participant pool included 38 healthy volunteers and 30 individuals diagnosed with major depressive disorder, along with 16 participants who slept normally as a control group. Each subject underwent three MRI sessions to monitor brain activity. The results showed that after a night of sleep deprivation, mood generally declined for most participants. Notably, 13 of the 30 patients with depression experienced a mood improvement after the sleep loss, while the remaining individuals showed no change or a worsening mood. Following a single night of restorative sleep, 20 individuals with depression reported a mood boost, whereas others did not experience a change or felt worse. In those whose mood improved, connectivity between the amygdala and the anterior cingulate cortex was markedly enhanced; in those without mood changes, this connectivity tended to decrease.
Researchers interpret this pattern as a possible marker of neural resilience to mood disorders after periods of sleep loss. They also point to the role of rapid eye movement sleep in this process. REM sleep is known to reduce norepinephrine levels, and its absence during insomnia may lessen the effectiveness of antidepressants for some people.
A historical aside notes that ancient Russian biologists explored how depression and stress influence brain oncogene activity, a line of inquiry that echoes pressing questions about the brain’s response to emotional states and sleep patterns today.