During sleep, cerebrospinal fluid waves rose less in older adults than in young adults

What the research found

A sleep imaging study was published online on 13 November 2026 in Nature Aging. Bailes, Williams, Lewis, and colleagues scanned people with fMRI and EEG. The sleep group was young adults aged 18 to 39 (n=31) and older adults aged 60 to 84 (n=41). The paper does not give a sex split. From wake to NREM sleep, low-frequency cerebrospinal fluid power rose by an average of 3.82 dB in the young group and 1.15 dB in the older group (P=0.002). The age-by-state interaction was P=0.025. The rise was clear within the young group (P=0.005) and not within the older group (P=0.354). During NREM, the older group sat below the young group (P<0.001). During wake the gap was smaller (P=0.034). Gray-matter blood-oxygen signal power rose 3.67 dB in young adults and 2.15 dB in older adults (P=0.038), with an age-by-stage interaction of P=0.021. Within sleep, that older-versus-young gap was P=0.003. The two signals still moved together (r=0.75, n=25 young; r=0.78, n=32 older). The peak cross-correlation was 0.67 (n=30 young) versus 0.42 (n=38 older), a difference of 0.25 (P<0.001). The authors tie the pattern to neural and cerebrovascular changes, in the context of brain health, before clinical disease. This is an observational scan study, not a treatment test. DOI 10.1038/s43587-026-01270-4. Not medical advice.

Evidence level: Human study. A study in people, but an association isn't proof of cause.

Read the original at Nature Aging