Research Library

The evidence behind every factor Halo asks about

Halo's longevity assessment asks about 22 factors across eight domains. This page lists the primary research behind each one — what the evidence actually shows, how strong it is, and where its limits are — with a link to the original study.

These summarize population-level associations from published research. They describe patterns across large groups of people, not a prediction about you specifically, and "association" is not the same as "if you change this, your risk changes by this amount." Where a factor has genuine randomized or interventional evidence behind it — blood pressure treatment, smoking cessation — we say so explicitly; most of what follows is observational, and we label it that way rather than implying otherwise.

How to read this page

Strong evidence
Moderate evidence
Limited evidence

Evidence quality is graded per factor, not for the assessment as a whole — some inputs (smoking, blood pressure) sit on a large, well-replicated evidence base; others (relationship quality, chronic stress) are genuinely more limited, and we say so rather than presenting every factor as equally certain. Each card also names the specific reliability or bias concerns that apply to that evidence — self-report accuracy, reverse causation, confounding — so the caveats sit next to the claim they qualify, not buried in a general disclaimer.

This page describes the supporting research for each input. It is not a description of the exact mechanics of how your answers are combined into a result.