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Home › Research › What the research found › Every row

Every row of the evidence table

One row per finding: what was tested, which way the result went, and how the study was built. The answer by area, and where the studies disagree, are on the main page.

Every row

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Area All 382 Care, carers and services 140 Medicines 85 Genes (not modifiable) 35 All modifiable factors together 27 Diet and supplements 23 Exercise and activity 21 Sleep, mood and social life 19 Hearing and vision 8 Alcohol, tobacco and cannabis 6 Infection and vaccination 5 Heart and metabolic health 4 Injury, delirium and falls 4 Environment 3 Cognitive activity 2
Question Both Prevention 190 Treatment 192
Direction Any Benefit 144 Harm 105 No effect 38 Mixed 37 No direction reported 58
Design Any meta-analysis 57 randomised trial 44 phase 3 trial 15 systematic review 9 phase 2 trial 10 cohort study 136 phase 1 trial 2 cross-sectional study 31 case-control study 14 modelling study 20 regulatory decision 7 company announcement 1 coverage determination 1 None 35
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Showing 7 of 382 rows for Sleep. One row per study per exposure: a study that tested two different things appears twice, once for each.

Scroll the table sideways to see every column.

Research and outcomes, 7 rows. Every row links to its source.
Exposure Question Direction Outcome measured Design People Effect size, as the source reported it Source
Sleep Sleep, mood and social life Prevention Benefit
why

Direction is for normal sleep versus sleep deprivation, on a clearance measure — not on cognition, which this trial did not measure.

 Overnight brain-to-plasma clearance of amyloid-beta and tau randomised trial 39 Additional variance explained by the physiological predictor model in the sleep condition: "between 49.1% (Abeta40) to 56.0% (Abeta42)" in amyloid-positive participants and "between 71.3% (p-tau181) to 97.8% (Abeta40)" in amyloid-negative participants Nature Communications 2026
✓ Peer-reviewed PMID 41593094
Sleep Sleep, mood and social life Prevention Harm
why

Eight kinds of sleep disturbance were analysed; both short and long sleep carried higher risk, as did excessive daytime sleepiness and insomnia.

 Cognitive decline or dementia meta-analysis not stated Excessive daytime sleepiness RR 1.41 for all-cause dementia; long sleep RR 1.66 for Alzheimer's disease Journal of Neurology 2025
✓ Peer-reviewed PMID 41081870
Sleep Sleep, mood and social life Prevention Mixed
why

Two findings point opposite ways: synchronised norepinephrine, blood-volume and CSF oscillations during natural NREM sleep were the strongest predictors of glymphatic clearance, while the sleep aid zolpidem suppressed those oscillations and glymphatic flow. Mouse work with no human outcome.

 Glymphatic clearance during NREM sleep in mice, its drivers (norepinephrine and vasomotion oscillations) and its suppression by zolpidem None not stated not established — pubmed abstract reports no numeric effect size. Cell 2025
✓ Peer-reviewed PMID 39788123
Sleep Sleep, mood and social life Prevention Harm
why

Direction is for LOSING slow-wave sleep. 52 cases in 346 people, so the estimate is imprecise, and slow-wave sleep also falls with Alzheimer's genetic risk, which muddies cause and effect.

 Incident dementia over 17 years cohort study 346 HR 1.27 (95% CI 1.06-1.54) per 1%/year loss of slow-wave sleep JAMA Neurology 2023
✓ Peer-reviewed PMID 37902739
Sleep Sleep, mood and social life Prevention Harm
why

No significant association with vascular dementia, and none of the 11 studies used biomarkers to confirm the diagnoses.

 Any neurocognitive disorder; Alzheimer's disease meta-analysis 1,333,424 HR 1.43 (95% CI 1.26-1.62) for any neurocognitive disorder; Alzheimer's HR 1.28 (1.16-1.41) Journal of Sleep Research 2022
✓ Peer-reviewed PMID 35366021
Sleep Sleep, mood and social life Prevention Harm
why

Direction is for SHORT sleep (6 hours or less): higher dementia risk than a 7-hour sleep duration.

 Incident dementia over 25 years cohort study 7,959 HR ~1.22 (age 50) and ~1.37 (age 60) for short vs. 7-hour sleep; persistent short sleep across ages 50/60/70 ~30% higher risk Nature Communications 2021
✓ Peer-reviewed PMID 33879784
Sleep Sleep, mood and social life Prevention No direction reported
why

A narrative review proposing glymphatic failure as a final common pathway to dementia. It reports no effect estimate.

 Dementia pathogenesis (glymphatic clearance of protein waste) None not stated not established — review; the abstract reports no effect estimate. Science 2020
✓ Peer-reviewed PMID 33004510

How this table was built, and where it is weak →