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Abstract

Background: Sleep disturbances elevate brain amyloid-beta (Aβ) levels and represent a modifiable risk factor for Alzheimer’s disease (AD). The orexin/hypocretin system regulates sleep–wake behavior and has emerged as a therapeutic target in AD; however, the effects of FDA-approved dual orexin receptor antagonists (DORAs) on amyloid pathology remain unclear. We compared lemborexant, an FDA-approved DORA, to doxepin, an antihistaminergic sleep medication, on amyloid pathology and microglial responses in PSAPP mice.

Methods: PSAPP mice received lemborexant (10 or 30 mg/kg/day), doxepin (35 mg/kg/day), or vehicle for 6 weeks beginning prior to plaque onset or 4 weeks after established pathology. Sleep was assessed by piezoelectric monitoring and EEG/EMG polysomnography. Amyloid pathology and microglial responses were quantified by immunohistochemistry, confocal microscopy, and single-cell RNA sequencing. Microglial depletion was induced with the CSF1R inhibitor PLX3397.

Results: Lemborexant enhanced sleep quality with less active-phase sedation than doxepin. Both drugs reduced initial diffuse plaque deposition, but only lemborexant prevented fibrillar plaque accumulation in young mice and slowed plaque growth in older mice. Lemborexant increased peri-plaque microglial CD68 expression and enhanced Aβ phagocytosis in vivo. Single-cell transcriptomics revealed a shift toward activated, DAM-like microglial states with upregulation of phagocytic genes without broad inflammatory induction. Microglial depletion abolished lemborexant’s anti-amyloid effects.

Conclusions: Lemborexant mitigates amyloid pathology by augmenting microglial phagocytic function, positioning DORAs as promising therapeutics that couple sleep promotion with beneficial microglial modulation.

Document Type

Article

Publication Date

2026

Notes/Citation Information

© The Author(s) 2026. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Digital Object Identifier (DOI)

https://doi.org/10.1186/s13024-026-00948-y

Funding Information

This work was supported by a sponsored research agreement between Eisai, Inc. and Washington University in St. Louis (PI: ESM).

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