Chronic pain and sleep disruption are frequent companions. People with neuropathic pain, pain caused by damage to the nervous system, commonly suffer from insomnia as well, and each condition worsens the other. Whether this comorbidity is a coincidence or the product of a shared neural mechanism has been unclear. A study published June 19 in Nature Communications provides an answer: the same population of neurons drives both.
The research, led by Haiting Fan, Yingying Su, and colleagues at Sun Yat-sen University, Southern Medical University, and Guangzhou Medical University in China, identifies a population of GABAergic neurons in the dorsal lateral septum (LS^GABA) whose hyperactivity simultaneously produces both mechanical allodynia, pain from normally non-painful stimuli, and sleep disruption in a mouse model of neuropathic pain.
The team used the spared nerve injury (SNI) model in adult male mice, a validated approach in which two of three branches of the sciatic nerve are ligated and transected, producing long-lasting neuropathic pain. They then applied a combination of fiber photometry (calcium imaging), chemogenetics, optogenetics, and EEG/EMG recordings to trace how the injury changed neural activity.
The result was a clear picture: after nerve injury, GABAergic neurons in the dorsal lateral septum become hyperactive. This hyperactivity, the team showed, acts through two distinct downstream circuits projecting to the lateral preoptic area (LPO), a brain region involved in sleep regulation and pain processing:
- LS^GABA neurons projecting to LPO glutamatergic neurons drive mechanical allodynia.
- LS^GABA neurons projecting to LPO GABAergic neurons drive sleep disruption.
The same upstream nucleus, the same population of cells, but two functionally distinct downstream pathways that separately control pain and sleep.
How dexmedetomidine works
Dexmedetomidine is a potent, highly selective α2-adrenergic receptor agonist used clinically as a sedative in intensive care and operating rooms. It is unusual among sedatives in that it produces a state resembling natural non-REM sleep, patients remain easily arousable with minimal respiratory depression, and it also has moderate analgesic properties.
The study reveals the circuit-level basis for this dual effect. Systemic or locally administered dexmedetomidine reduces LS^GABA hyperactivity by activating α2A adrenergic receptors on the lateral septum neurons themselves. This single intervention then modulates both downstream pathways simultaneously: it calms the LPO glutamatergic neurons to relieve pain, and the LPO GABAergic neurons to restore sleep.
Why this matters
Chronic pain and insomnia are among the most common and debilitating comorbidities in medicine. Approximately 50-80% of people with chronic pain report sleep disturbances, and poor sleep is known to lower pain thresholds, creating a vicious cycle. Current treatments often address one condition at the expense of the other, opioids may disrupt sleep architecture, while sleep aids do nothing for pain.
This study suggests that the comorbidity is not a coincidence but a consequence of shared neural circuitry. It also provides a specific mechanism, the α2A receptor in the lateral septum, through which a single drug can simultaneously improve both conditions. For an already-approved clinical agent like dexmedetomidine, this opens the possibility of more targeted applications in patients with comorbid chronic pain and sleep disorders.
Caveats
The most important limitation is that the study was conducted exclusively in male mice. Sex differences in pain processing, sleep regulation, and drug responses are well documented, and the authors explicitly acknowledge this in their title. Whether the same circuit mechanism operates in females, and ultimately in humans, remains unknown.
The research was supported by the National Natural Science Foundation of China and other Chinese institutional sources. The authors declared no competing interests.
Source: Fan, H., Su, Y., Deng, J. et al. “Lateral septum GABAergic neurons mediate the effects of dexmedetomidine on allodynia and sleep in a male mouse model of neuropathic pain.” Nature Communications (2026). DOI: 10.1038/s41467-026-74217-3.