How Bright-Light Treatment Improves Sleep in Stress-Induced Disturbances?

Persistent stress is linked to sleep disturbances, and researchers have identified the neural pathway responsible for this phenomenon while also explaining how bright-light therapy can effectively alleviate it. The research was conducted in mice at Jinan University in China and published in the open access journal PLOS Biology. (1^✔ ✔Trusted Source
Bright light treatment counteracts stress-induced sleep alterations in mice, via a visual circuit related to the rostromedial tegmental nucleus

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Bright-Light Therapy Enhances Sleep Quality In Stressed Mice

Bright-light treatment is known to improve sleep in those with sleep disorders, but how it works – and whether it works in cases of stress-induced sleep disturbances – was unknown. The researchers hypothesized that a part of the brain called the lateral habenula is deeply involved in this phenomenon because it both receives light signals from the eyes and can influence other parts of the brain that regulate sleep. To test this theory and fully characterize the neural pathway, the team performed a series of chemogenetic and optogenetic studies in a mouse model of chronic stress, which also showed irregular sleep. As hypothesized, the lateral habenula influenced the effects of stress on sleep. Its chemogenetic inhibition in stressed mice prevented the unusual high amounts of non-REM sleep, and on the flip side, its chronic activation in un-stressed mice resulted in extra non-REM sleep. Next, by separately activating habenular neurons that send signals to different regions of the brain, the researchers were able to identify the connection between the habenula and the rostromedial tegmental nucleus (RMT) as critical. Activating only these neurons mimicked the effects of stress on sleep, while inhibiting them in stressed mice mimicked the effects of bright-light treatment.

Lastly, the researchers showed that light-sensitive neurons in the lateral geniculate nucleus (LGN) naturally inhibit the habenula-RMT neurons, which explains why bright-light treatment can reduce stress-induced abnormalities in non-REM sleep.

Coauthor Chaoran Ren adds, “A circuit mechanism has been identified that explains the effects of bright light treatment on sleep disruptions induced by chronic stress in mice.”

Reference:

1. Bright light treatment counteracts stress-induced sleep alterations in mice, via a visual circuit related to the rostromedial tegmental nucleus - (https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3002282)

Source-Eurekalert