In this study on male mice, the authors clearly demonstrate that sleep is the therapeutic window for photobiomodulation (PBM). Indeed, PBM during sleep but not under awake effectively improves the removal of toxic metabolites from the aging brain. Chronic sleep deprivation (CSD) exacerbates accumulation of metabolites in the brain, and more significantly in old mice than in young and middle-aged animals. However, old mice, unlike young and middle-aged mice, are insensitive to PBM+wake, which is not effective in stimulation of brain drainage and removing metabolites from its tissues. Importantly, in old mice, only PBM+sleep increases resistance to CSD by maintaining brain metabolites at the basal levels through stimulation of brain drainage, which is associated with improved cognitive function. Thus, PBM+sleep opens up new possibilities for the effective use of phototherapy for diseases of the aging brain as well as for maintaining active longevity.
For more details, please refer to the article entitled “Sleep is a therapeutic window for photostimulation of drainage of aging brain” by Terskov Andrey et al., Front. Optoelectron., 2025, 18(4): 22.
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