Self-administered daytime indoor light supplementation is feasible in older adults, with earlier and longer supplementation (onset before 10:00) associated with greater daytime activity and lower rest-activity fragmentation, confirming this simple, non-pharmacological, low-cost intervention has broad potential to support healthy ageing in urban settings.
Key Findings
Results
Greater naturalistic light exposure was associated with increased daytime activity, consolidated wakefulness, better subjective sleep quality, and reduced metabolic disorder incidence in older adults.
Study recruited 202 participants aged 63-92 years (139 females) across three EU cities at different latitudes: Amsterdam, Bologna, and Tartu.
A 2-week baseline assessment used wearables and daily diaries to measure light exposure, rest-activity patterns, and sleep.
Associations between naturalistic light exposure and health outcomes were observed across the full sample prior to intervention.
Metabolic disorder incidence was among the outcomes inversely associated with greater naturalistic light exposure.
Results
Individuals with lower naturalistic light exposure self-initiated earlier and longer indoor light supplementation across seasons.
Participants randomized to light supplementation (N = 98) self-directed their own lamp use in their most frequently used room.
The lamp provided greater than 8000 melanopic EDI (equivalent daylight illuminance), a measure of the circadian-effective component of light.
The self-directed nature of supplementation revealed that those with least ambient light exposure compensated by using the lamp earlier and for longer durations.
This pattern was observed across different seasons, suggesting a naturalistic compensatory behavior.
Results
Supplementation onset before 10:00 was associated with greater daytime activity and lower rest-activity fragmentation.
Among participants in the light supplementation group (N = 98), the timing of lamp use onset was a key determinant of outcome.
Starting light supplementation before 10:00 AM was specifically linked to improved daytime activity levels.
Earlier supplementation onset was also associated with lower rest-activity fragmentation, indicating more consolidated and robust circadian rhythms.
These findings highlight that timing of light supplementation, not just duration or intensity, is an important factor in real-world efficacy.
Methods
The study design involved a 12-week randomized intervention comparing self-implemented indoor light supplementation to a no-intervention control group in older adults across three EU cities.
202 participants (63-92 years; 139 females) were enrolled in this interventional, prospective, randomised study.
Cities were Amsterdam (Netherlands), Bologna (Italy), and Tartu (Estonia), representing different latitudes and thus different ambient light environments.
The intervention group (N = 98) used a lamp (>8000 melanopic EDI) placed in their most frequently used room for 12 weeks.
A 2-week baseline assessment preceded randomization, and a subsequent 2-week reassessment followed the 12-week intervention period.
Outcomes were measured through wearables and daily diaries capturing light exposure, rest-activity patterns, and sleep.
Background
Reduced ocular light sensitivity associated with natural ageing exacerbates low daytime indoor light exposure in urban housing, making older adults a critical population for light supplementation interventions.
Natural ageing is associated with reduced ocular light sensitivity, which diminishes the circadian system's response to light.
Low daytime indoor light exposure is common in urban housing environments for older adults.
These two factors compound each other, increasing the risk of circadian disruption, poor sleep, and mood disturbances in this population.
Controlled studies have previously demonstrated that light supplementation benefits circadian entrainment, sleep, and mood, but translation to real-world settings had not been well established.
Results
The real-world feasibility of self-directed light supplementation was confirmed in a diverse older adult population across multiple European cities and seasons.
Participants were able to self-administer light supplementation using a lamp placed in their most frequently used room without supervised guidance.
The study spanned three cities at different latitudes, capturing variation in natural light environments across seasons.
The 12-week duration and multi-site design demonstrated that self-directed use was sustainable across a range of environmental and personal contexts.
The authors characterize the intervention as 'simple, non-pharmacological, and low-cost,' with 'broad potential to support healthy ageing in urban settings.'
What This Means
This research suggests that older adults living in cities may not be getting enough bright light during the day, and that this lack of light is linked to poorer sleep, less physical activity, and greater fragmentation of daily rest-activity cycles. As people age, their eyes become less sensitive to light, which makes it harder for their internal body clocks to stay properly synchronized. This study, conducted across three European cities (Amsterdam, Bologna, and Tartu) with 202 adults aged 63 to 92, tested whether giving older adults a bright lamp to use at home — at their own discretion — could help address these problems.
The study found that people who naturally got less light during the day tended to use the supplemental lamp earlier in the morning and for longer periods, suggesting that individuals intuitively compensated for their low light exposure. Importantly, those who started using the lamp before 10:00 AM showed greater daytime activity levels and more consolidated, less fragmented rest-activity patterns compared to those who used it later. Greater exposure to natural daylight was also associated with better subjective sleep quality and lower rates of metabolic disorders.
This research suggests that a simple, inexpensive bright lamp — used by older adults in their own homes without professional supervision — could be a practical tool to support healthier aging. The findings are particularly relevant for older people living in northern cities or spending most of their time indoors, where natural light exposure is limited. The study emphasizes that the timing of light use (earlier in the day) may matter as much as whether light supplementation is used at all, pointing toward guidance that could help maximize benefits for this population.
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Constantino D, Baccari F, Caporali L, Carelli V, Amore G, Gordijn M, et al.. (2026). ENLIGHTENme: Translating the Benefits of Self-Administered Daytime Light Supplementation to Older Adults in the Real World.. Journal of pineal research. https://doi.org/10.1111/jpi.70174