Population Based Lighting Study on Older Adults

The ENLIGHTENme project is a population-based study examining how both outdoor (street, public) and indoor lighting environments affect the health and wellbeing of residents across three European cities — Bologna (Italy), Amsterdam (The Netherlands), and Tartu (Estonia). The study specifically focuses on older adults, a group whose circadian systems are particularly vulnerable to light-dark disruption due to age-related changes in photoreceptor sensitivity and melatonin production. Researchers are building an open-access 'Urban Lighting and Health Atlas' that maps existing lighting data alongside health and socioeconomic indicators. A core aim is to identify whether inequalities in lighting quality (e.g., light pollution in some areas, under-lighting in others) translate into measurable health inequalities between neighbourhoods and demographic groups. By correlating real-world lighting exposure with biological health outcomes, the project moves circadian science out of the laboratory and into urban-planning policy. The ultimate goal is to generate evidence that city planners and public health authorities can use to design lighting environments that support rather than disrupt human circadian biology. This is especially timely given the rapid global rollout of high-intensity LED street lighting, whose blue-spectrum content can significantly suppress nocturnal melatonin.

• No quantitative results are yet publicly reported (study status: completed May 2026; findings pending publication) — all findings below are best-effort inferences from the registered protocol and project description.
• The study is designed to detect correlations between objectively characterised urban lighting (intensity, spectrum, timing) and health/wellbeing outcomes in older adult populations across three cities with distinct latitude, climate, and urban-form profiles.
• A key structural output is an open Urban Lighting and Health Atlas, intended to systematise existing European data on lighting conditions and health metrics and serve as a reusable resource for future circadian-epidemiology research.

This is an observational, population-based epidemiological study embedded in the multi-city ENLIGHTENme consortium project. Pilot sites are Bologna (Italy), Amsterdam (The Netherlands), and Tartu (Estonia), chosen to capture variation in latitude, urban density, and lighting infrastructure. The protocol involves characterisation of outdoor and indoor light environments (likely via wearable light loggers and/or geospatial luminance mapping) alongside collection of health, wellbeing, and socioeconomic data from community-dwelling older adults. Sample size, precise measurement instruments, and follow-up duration are not fully specified in the available registration abstract — methods confidence is therefore low.

Because only the registration abstract is publicly available, key methodological details — sample sizes, specific health biomarkers, light-exposure measurement tools, and whether the design is cross-sectional or longitudinal — cannot be confirmed, and all methodological inference should be treated as low-confidence. As an observational study, ENLIGHTENme cannot establish causality between lighting conditions and health outcomes; unmeasured confounders (indoor time-use patterns, medication affecting circadian biology, pre-existing disease) may explain observed associations. The three-city design, while geographically diverse, limits generalisability to non-European, non-urban, or lower-income contexts where lighting environments differ substantially. A natural next experiment would be a randomised intervention trial installing circadian-optimised (tunable, dim-at-night) street or indoor lighting in matched neighbourhoods, with pre-/post- measurement of melatonin, sleep quality, and cardiometabolic markers in older residents.

ENLIGHTENme sits at the translational bridge between mechanistic circadian science and public-health policy, directly paralleling [§133], which investigates how light exposure and circadian disruption interact with central oxidative stress pathways — the population-level lighting gradients ENLIGHTENme maps could produce exactly the biological perturbations [§133] characterises at the molecular level. The project extends [§31], whose open-source DLMO tooling (dim-light melatonin onset measurement) represents the kind of standardised, shareable circadian-assessment infrastructure that a multi-city lighting atlas would need to incorporate to move from self-reported wellbeing to objective circadian biomarkers. It also contextually parallels [§33] (the TREAD time-restricted eating trial for Alzheimer's disease), in that both studies treat circadian entrainment as a modifiable environmental exposure relevant to neurological ageing — ENLIGHTENme targets the light arm of that entrainment system at population scale. Findings from ENLIGHTENme will be most interpretable alongside [§44], which details how the CLOCK-BMAL1 molecular machinery mediates circadian regulation and thus provides the mechanistic framework needed to explain any lighting–health correlations the atlas uncovers.

• Sleep, Light, Circadian, Central Oxidative Stress
  Directly mechanistically complementary: where ENLIGHTENme measures population-level light exposure and health outcomes, this article probes the biological pathway (circadian disruption → central oxidative stress) that likely mediates those outcomes.
• dlmoR: An open-source R package for the dim-light melatonin onset (DLMO) hockey-stick method
  Methodologically relevant: the dlmoR open-source DLMO package represents the type of validated, standardised circadian biomarker tool that a population lighting atlas would need to adopt to upgrade beyond self-reported wellbeing endpoints.
• The CLOCK-BMAL1 complex in circadian regulation: structure, mechanisms, and therapeutic targeting
  Provides the molecular mechanistic backbone (CLOCK-BMAL1 circadian regulation) against which any lighting-exposure correlations identified in this population study can be interpreted causally.
• TREAD: Time Restricted Eating Intervention for Alzheimer's Disease
  Parallel population of interest (older adults at risk for neurodegeneration) and parallel logic (modifying an environmental circadian signal to improve neurological outcomes), enabling cross-comparison of light vs. feeding-time as entrainment levers.
• Effects of chronic jetlag on high-fat and high-fructose diet induced renal injury in mice
  Offers a contrasting experimental-model perspective on chronic circadian misalignment (jet-lag paradigm in animals) that anchors the health risks ENLIGHTENme seeks to detect in free-living human populations.