研究使用英国生物银行 27,500 名中老年参与者（平均 54.7 岁），先以 5 个面向评估睡眠（作息型态、睡眠时长、失眠、打鼾、日间嗜睡），约 9 年后以 MRI 扫描并用机器学习估算「生物学脑年龄」。依睡眠型态分组：41.2% 为健康睡眠、3.3% 为明显差睡眠、55.6% 介于两者之间。

量化结果显示：健康睡眠分数每下降 1 点，脑年龄与实际年龄的差距平均增加约 6 个月；睡眠最差组的脑年龄约比实际年龄老 1 年。与脑老化关联特别强的因素包括夜猫型作息、睡眠时长偏离 7–8 小时，以及打鼾；且五项因素彼此交互影响（例如失眠导致日间嗜睡、夜猫型作息导致睡眠变短）。

机制方面，研究以多种低度慢性发炎生物标记（如 C 反应蛋白、白血球与血小板计数、颗粒球/淋巴球比值）建构发炎指标。结果确认发炎程度越高，脑年龄越大；中介分析显示，发炎可解释「中等睡眠型态」与脑老化关联的约 7%，并解释「差睡眠型态」关联的超过 10%。这支持差睡眠提高慢性发炎风险、进而加速脑老化；另可能途径还包括影响睡眠期的脑淋巴系统清除废物，以及恶化心血管健康而间接损害脑部血流与组织。

In 27,500 UK Biobank participants (mean age 54.7), sleep was scored across five dimensions—chronotype, duration, insomnia, snoring, and daytime sleepiness—and brain MRI about nine years later was used with machine-learning models to estimate biological “brain age.” Participants clustered into three patterns: 41.2% healthy sleep, 55.6% intermediate, and 3.3% clearly poor sleep.

Quantitatively, each 1-point drop in the healthy sleep score corresponded to an average increase of about six months in the gap between brain age and chronological age; the poorest-sleep group had brains roughly one year older than their actual age. Stronger links to accelerated brain aging were seen with night-owl chronotype, sleep duration outside 7–8 hours, and snoring, with the five sleep factors also interacting (e.g., insomnia promoting daytime sleepiness and eveningness shortening sleep).

To probe mechanisms, the team combined low-grade inflammation biomarkers (including C-reactive protein, white blood cell and platelet counts, and the granulocyte-to-lymphocyte ratio) into an inflammation measure. Higher inflammation tracked with higher brain age, and mediation analyses suggested inflammation explained ~7% of the intermediate-sleep association and >10% of the poor-sleep association with brain aging. This supports a pathway where poor sleep raises chronic inflammation that, in turn, speeds brain aging, alongside other plausible routes such as impaired glymphatic waste clearance during sleep and worsened cardiovascular health affecting brain blood flow and tissue.