{"publication_id":"2bfbccd9-9cf4-4d24-8611-5246bfea4d12","content_hash":"sha256:84f93cfd9ca6566a968d119b74a2acd5dbe2e3de6796b8809e48cbc5aad1d60b","nodes":[{"id":"2bfbccd9-9cf4-4d24-8611-5246bfea4d12","type":"publication","title":"Research Synthesis: Circadian Light Timing — full paper"},{"id":"claim_1","type":"claim","text":"What does the current evidence establish about Circadian Light Timing and human geroscience? This synthesis tests the thesis that evidence for Circadian light timing is context-dependent, separating outcome-specific signals from broader claims and identifying the evidence gaps that should bound interpretation. Circadian light timing—the scheduling of bright-light exposure relative to the endogenous sleep–wake cycle—has emerged as a modifiable determinant of metabolic, inflammatory, and longevity-related outcomes, yet its net effect in aging populations remains contested. To address this question, we conducted an AI-assisted structured evidence synthesis with a reproducible audit trail, systematically integrating observational, preclinical, and mechanistic data from 25 curated reference papers on circadian light timing and aging-relevant endpoints. Translational relevance to humans remains uncertain. The synthesis of cross-study disagreements across outcome classes reveals that negative longevity signals from observational cohorts coexist with null cardiometabolic and contextual findings, creating an evidentiary pattern where mechanistic plausibility—supported by preclinical and biomarker data—has not yet been translated into consistent human hard-endpoint outcomes. We conclude that circadian light timing likely exerts a biologically real influence on aging trajectories through immune, amyloid, and telomere-related pathways, but the human evidence is constrained by obse"},{"id":"claim_2","type":"claim","text":"This manuscript is reported as a Evidence brief. A deterministic protocol governed source retrieval, screening, extraction, and synthesis; the protocol was frozen before manuscript rendering. The full audit trail is in the supplementary `methods_pack.json` and the timestamped submission directory `synthesis-circadian_light_timing-v06-DAILY-2026-05-29T05-40-50Z`."},{"id":"claim_3","type":"claim","text":"The following fields were extracted from each included source: study design, population / cohort, intervention or exposure, comparator, outcome class, effect direction, effect size, confidence interval or credible interval, p-value, sample size, follow-up duration, risk-of-bias rating."},{"id":"claim_4","type":"claim","text":"Per-source risk-of-bias was rated using design-appropriate Cochrane RoB-2 (RCTs), ROBINS-I (non-randomised studies), and AMSTAR-2 (systematic reviews / meta-analyses). Ratings recorded in `risk_of_bias.json`."},{"id":"claim_5","type":"claim","text":"Evidence-tension synthesis: claims grouped by outcome class (cardiometabolic, contextual adjacent evidence, immune and inflammation, longevity, mortality and survival); within-class agreement, disagreement, and directness gaps surfaced explicitly. Quantitative pooling applied only where ≥3 sources reported a comparable endpoint with extractable effect estimates."},{"id":"claim_6","type":"claim","text":"Source retrieval, claim extraction, evidence routing, and prose drafting were assisted by large language models under a deterministic audit-trail protocol. Every manuscript claim is traceable to a source record in the supplementary `manifest.json`. Final eligibility and interpretation decisions are author-verified."},{"id":"claim_7","type":"claim","text":"Outcome-class note:** Contextual Adjacent Evidence denotes background, boundary-condition, or adjacent-outcome sources. It is not pooled with direct outcome evidence."},{"id":"claim_8","type":"claim","text":"| Contextual Adjacent Evidence | n=14; claims=345 | null signal in 14/14 sources | 10 indirect; 2 mechanistic; 2 review | limited corpus depth in this outcome class |"},{"id":"claim_9","type":"claim","text":"| Cardiometabolic | n=3; claims=180 | null signal in 3/3 sources | 2 indirect; 1 review | limited corpus depth in this outcome class |"},{"id":"claim_10","type":"claim","text":"| Immune and Inflammation | n=2; claims=121 | null signal in 2/2 sources | 2 indirect | limited corpus depth in this outcome class |"},{"id":"claim_11","type":"claim","text":"This evidence brief reports outcome packets as a map of retained evidence rather than as a full journal Results narrative or pooled effect estimate."},{"id":"claim_12","type":"claim","text":"14 included sources were assigned to this outcome class. Directional coding: null=14. Directness coding: indirect=10, mechanistic=2, review=2."},{"id":"claim_13","type":"claim","text":"5 included sources were assigned to this outcome class. Directional coding: mixed=1, negative=1, null=1, unclear=2. Directness coding: indirect=4, review=1."},{"id":"claim_14","type":"claim","text":"3 included sources were assigned to this outcome class. Directional coding: null=3. Directness coding: indirect=2, review=1."},{"id":"claim_15","type":"claim","text":"2 included sources were assigned to this outcome class. Directional coding: null=2. Directness coding: indirect=2."},{"id":"claim_16","type":"claim","text":"Outcome-class note:** Contextual Adjacent Evidence denotes background, boundary-condition, or adjacent-outcome sources. It is not pooled with direct outcome evidence."},{"id":"claim_17","type":"claim","text":"| Contextual Adjacent Evidence | n=14; claims=345 | null signal in 14/14 sources | 10 indirect; 2 mechanistic; 2 review | limited corpus depth in this outcome class |"},{"id":"claim_18","type":"claim","text":"| Cardiometabolic | n=3; claims=180 | null signal in 3/3 sources | 2 indirect; 1 review | limited corpus depth in this outcome class |"},{"id":"claim_19","type":"claim","text":"| Immune and Inflammation | n=2; claims=121 | null signal in 2/2 sources | 2 indirect | limited corpus depth in this outcome class |"},{"id":"claim_20","type":"claim","text":"This evidence brief reports outcome packets as a map of retained evidence rather than as a full journal Results narrative or pooled effect estimate."},{"id":"claim_21","type":"claim","text":"14 included sources were assigned to this outcome class. Directional coding: null=14. Directness coding: indirect=10, mechanistic=2, review=2."},{"id":"claim_22","type":"claim","text":"5 included sources were assigned to this outcome class. Directional coding: mixed=1, negative=1, null=1, unclear=2. Directness coding: indirect=4, review=1."},{"id":"claim_23","type":"claim","text":"3 included sources were assigned to this outcome class. Directional coding: null=3. Directness coding: indirect=2, review=1."},{"id":"claim_24","type":"claim","text":"2 included sources were assigned to this outcome class. Directional coding: null=2. Directness coding: indirect=2."},{"id":"claim_25","type":"claim","text":"Verification note:** Reference-only or no-abstract records are treated as verification-limited context, not as equal-weight support for the main claim."},{"id":"claim_26","type":"claim","text":"The curated corpus is dominated by observational cohort designs, with no long-term mortality randomized controlled trial (RCT) directly testing a circadian light-timing intervention included among the 25 accepted references. Without at least one adequately powered RCT that randomizes participants to a defined light-exposure prescription and follows them to a hard mortality endpoint, the causal arrow from light timing to survival cannot be established within this corpus. Similarly, cardiometabolic outcomes are informed only by indirect observational evidence (Hu 2025; Reytor-Gonzalez 2025) and a chrononutrition review (Nadeem 2024) rather than by a light-specific intervention trial. The absence of a diurnal-light RCT in non-diabetic community-dwelling adults leaves the headline cardiometabolic conclusion grounded entirely in surrogate or associational data, a limitation that aligns with the general caution that surrogate associations do not guarantee hard-outcome validity (Ioannidis 2005). Practitioners should therefore interpret the survival and metabolic findings as hypothesis-generating rather than practice-changing."},{"id":"claim_27","type":"claim","text":"Several outcome domains within the synthesis are supported by only a single source, precluding internal replication and amplifying the risk that a lone effect estimate reflects study-specific confounding. Blunted rest-activity rhythm amplitude and its association with all-cause, cardiovascular, and cancer mortality is documented solely by Xu 2022; no second independent cohort in the corpus reports the same relative-amplitude metric. When an entire mechanistic chain rests on one experiment—such as King 2025 showing that constant light accelerates amyloid-β plaque accumulation in 5xFAD mice—the generalizability to humans cannot be triangulated within the corpus. Single-trial outcomes should be flagged for readers as needing independent replication before informing clinical recommendations."},{"id":"claim_28","type":"claim","text":"Verification note:** Reference-only or no-abstract records are treated as verification-limited context, not as equal-weight support for the main claim."},{"id":"claim_29","type":"claim","text":"The curated corpus is dominated by observational cohort designs, with no long-term mortality randomized controlled trial (RCT) directly testing a circadian light-timing intervention included among the 25 accepted references. Without at least one adequately powered RCT that randomizes participants to a defined light-exposure prescription and follows them to a hard mortality endpoint, the causal arrow from light timing to survival cannot be established within this corpus. Similarly, cardiometabolic outcomes are informed only by indirect observational evidence (Hu 2025; Reytor-Gonzalez 2025) and a chrononutrition review (Nadeem 2024) rather than by a light-specific intervention trial. The absence of a diurnal-light RCT in non-diabetic community-dwelling adults leaves the headline cardiometabolic conclusion grounded entirely in surrogate or associational data, a limitation that aligns with the general caution that surrogate associations do not guarantee hard-outcome validity (Ioannidis 2005). Practitioners should therefore interpret the survival and metabolic findings as hypothesis-generating rather than practice-changing."},{"id":"claim_30","type":"claim","text":"Several outcome domains within the synthesis are supported by only a single source, precluding internal replication and amplifying the risk that a lone effect estimate reflects study-specific confounding. Blunted rest-activity rhythm amplitude and its association with all-cause, cardiovascular, and cancer mortality is documented solely by Xu 2022; no second independent cohort in the corpus reports the same relative-amplitude metric. When an entire mechanistic chain rests on one experiment—such as King 2025 showing that constant light accelerates amyloid-β plaque accumulation in 5xFAD mice—the generalizability to humans cannot be triangulated within the corpus. Single-trial outcomes should be flagged for readers as needing independent replication before informing clinical recommendations."},{"id":"source_1","type":"source","study":"Hu 2025","year":2025,"doi":"10.1186/s12889-025-25126-5","url":"https://doi.org/10.1186/s12889-025-25126-5","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level"},{"id":"source_2","type":"source","study":"Cheng 2024","year":2024,"doi":"10.3390/ijms25137458","url":"https://doi.org/10.3390/ijms25137458","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level"},{"id":"source_3","type":"source","study":"Panagiotou 2024","year":2024,"doi":"10.3390/nu16213700","url":"https://doi.org/10.3390/nu16213700","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level"},{"id":"source_4","type":"source","study":"Shim 2024","year":2024,"doi":"10.1038/s41746-024-01111-x","url":"https://doi.org/10.1038/s41746-024-01111-x","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level"},{"id":"source_5","type":"source","study":"Windred 2024","year":2024,"doi":"10.1073/pnas.2405924121","url":"https://doi.org/10.1073/pnas.2405924121","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level"},{"id":"source_6","type":"source","study":"Lai 2025","year":2025,"doi":"10.1111/nicc.70241","url":"https://doi.org/10.1111/nicc.70241","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level"},{"id":"source_7","type":"source","study":"Arbizu 2025","year":2025,"doi":"10.3390/nu17050784","url":"https://doi.org/10.3390/nu17050784","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level"},{"id":"source_8","type":"source","study":"PuigNavarro 2025","year":2025,"doi":"10.1111/jsr.14444","url":"https://doi.org/10.1111/jsr.14444","population":"not 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