A study of young people at risk for bipolar disorder found that unstable sleep-wake cycles are connected to mania symptoms through measurable changes in brain wiring.
A new brain imaging study has identified a biological pathway connecting disrupted sleep patterns to mania symptoms in young people at risk for bipolar disorder. The research, posted as a preprint on medRxiv in January 2026, found that the link runs through white matter microstructure, the wiring that connects different regions of the brain.
The study recruited 112 participants aged 16 to 24 across a spectrum of mania vulnerability. Each wore an actigraphy device (essentially a research-grade fitness tracker) for 14 days to measure their rest-activity rhythms, followed by a brain imaging session using diffusion MRI, which measures the structural integrity of white matter tracts.
The results showed that people with more unstable rest-activity rhythms, meaning their sleep-wake patterns were irregular from day to day, had measurable differences in their white matter microstructure. Those white matter differences, in turn, were associated with higher mania symptoms. In statistical terms, white matter served as a mediator between sleep disruption and mania.
Why This Matters
Clinicians have long known that sleep disruption is one of the most reliable triggers of manic episodes. Patients, families, and doctors all report that erratic sleep patterns often precede a manic episode by days or weeks. But the biological mechanism behind that connection has been unclear.
This study offers a potential explanation: disrupted circadian rhythms may gradually alter the brain’s white matter, weakening the structural connections that help regulate mood. Once those connections are compromised, the brain becomes more vulnerable to mania.
Critically, the researchers found that these white matter changes predicted future increases in mania symptoms. That suggests the relationship is not just correlational. Disrupted sleep may actually accelerate the progression toward mania in vulnerable individuals.
The finding has practical implications. Rest-activity rhythm instability is measurable with a wristwatch-like device and is potentially modifiable through behavioral interventions such as sleep hygiene, light therapy, and social rhythm therapy. If future research confirms this pathway, stabilizing sleep patterns could become an even more central part of mania prevention.
The study is a preprint and has not yet undergone peer review. It should be interpreted with that limitation in mind.
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