Scientists uncover how mis-spliced microexons disrupt sleep and trigger hyperactivity

A new study has uncovered a biological link between disrupted neuronal microexons and severe sleep disturbances. The research shows that mis-spliced microexons trigger hyperarousal and insomnia in zebrafish, with implications for human neurodevelopmental disorders. Scientists found that this mechanism involves elevated levels of cyclic adenosine monophosphate (cAMP), which acts as an internal regulator of brain activity. The study revealed that abnormal patterns of tiny neuronal microexons cause a sharp rise in cAMP levels within the forebrain. This spike permanently overexcites neurons, leading to daytime hyperactivity, sensory hypersensitivity, and chronic sleep deprivation. Researchers confirmed that the same mechanism has been observed in fruit flies, suggesting it is conserved across species, including mammals and humans.

To test their findings, scientists manipulated cAMP levels in zebrafish. Raising cAMP in normal fish produced hyperactive behaviour. Conversely, introducing a chemical inhibitor to lower cAMP in mutated zebrafish restored normal swimming patterns and sleep. This demonstrates a direct causal link between microexon mis-regulation, cAMP spikes, and hyperarousal. The discovery provides a clear biological explanation for sleep disturbances and anxiety in conditions like autism and schizophrenia. By targeting cAMP levels, researchers were able to reverse hyperactivity and insomnia in zebrafish. This suggests potential therapeutic pathways for treating similar symptoms in humans.