Biology subjects

Didikoglu, A.

Publications and source records attributed to Didikoglu, A..

4 recordsLinked to original sources

bioRxiv2026

Acute and cumulative light exposure differentially influence mood in healthy adults

Light influences mood in both clinical and experimental settings, yet it remains unclear how ambient light exposure relates to mood in daily life, which dimensions of mood are most sensitive to light and over what timescales these associations emerge. Here, we combined continuous personal light monitoring using wearable light sensors with repeated assessments of multiple dimensions of mood and affect, including self-reported mood ratings and cognitive measures of affective bias, alongside physiological monitoring in 49 healthy adults living under naturalistic conditions. Brighter light was consistently associated with more positive self-reported mood. Associations emerged over distinct temporal windows, with greater melanopic irradiance during the preceding 30 min associated with increased feelings of energy. Importantly, this association remained significant after accounting for alertness, physical activity and sleep-related covariates, suggesting that it is not solely explained by the established alerting effects of light. In contrast, several positive mood dimensions, including happiness, feeling accompanied, enjoyment, motivation and relaxation, were associated with light accumulated over longer periods (60-240 min). Furthermore, happiness, feeling accompanied, enjoyment and relaxation, but not energy, were also associated with greater cumulative daily exposure to light above 250 lux melanopic equivalent daylight illuminance (EDI), a threshold proposed to support healthy daytime light exposure. Behavioural measures of affective bias showed no robust associations with light exposure. Together, these findings indicate that everyday light exposure is associated with distinct dimensions of mood over different timescales, highlighting a complex relationship between light and affect in daily life. Significance StatementLight is a promising target for improving mental health, yet little is known about how everyday light exposure relates to mood outside laboratory and clinical settings. Using wearable light sensors and repeated mood assessments in healthy adults living under naturalistic conditions, we show that different dimensions of mood are linked to light exposure over distinct timescales, from recent exposure to cumulative light history. Importantly, the association between recent light exposure and feelings of energy remained independent of physical activity and sleep-related factors. These findings demonstrate that effects of light on mood are dynamic and multidimensional, highlighting the need to move beyond simple measures of total light exposure and informing future efforts to design healthier light environments that support emotional wellbeing.

neuroscience↗

bioRxiv2026

Toward scalable ambulatory light dosimetry: sensor-placement bias under naturalistic conditions

BackgroundPersonal light dosimeters enable exposure assessment under free- living conditions, but sensors are rarely positioned near the eyes--the relevant site for visual and non-visual responses. Chest and wrist placement may improve adherence and scalability, yet placement-dependent error and its consequences for derived outcomes remain insufficiently characterised. ObjectiveTo quantify how chest and wrist placement affects time-resolved estimates of eye-level light exposure across naturalistic contexts and derived exposure metrics. MethodsWe analysed concurrent 10-s melanopic equivalent daylight illuminance measurements from identical dosimeter models at the glasses, chest, and wrist across eight sites in seven countries. Melanopic equivalent daylight illuminance was compared at two analytical scales. Generalised additive mixed models quantified time-resolved placement error across contexts (N=787 participant-days), and mixed- effects models compared 54 daily metrics (N=604 participant-days). Hierarchical bootstrap resampling quantified the precision of population-average metric bias across participant numbers and monitoring durations. ResultsBody-worn dosimeters generally underestimated eye-level exposure. Across categorical contexts, estimated mean errors ranged from -23.1% to -4.2% at the chest and from -54.7% to -30.3% at the wrist, with larger errors generally observed at night. Nineteen of 54 chest-derived and 27 of 54 wrist-derived metrics differed nominally from glasses. Among these, median absolute bias was 5% at both placements, but maxima reached 50% and 84%, respectively. Timing outcomes were comparatively insensitive, whereas level and temporal-dynamics outcomes were more sensitive. With seven days per participant, the class-median bias standard deviation reached the 5% precision tolerance with 2-16 participants for all classes except temporal dynamics, which required 33 at the chest and 59 at the wrist. SignificanceDosimeter-placement validity depends on analytical scale and exposure construct. Chest placement can support scalable studies focused on aggregated timing or duration outcomes, whereas wrist placement introduces greater and less predictable bias. Near-eye measurement remains preferable for small- sample studies, time-resolved exposure levels and temporal-dynamics analyses.

physiology↗

bioRxiv2026

Individual, behavioural, and environmental determinants of personal light exposure in daily life: A multi-country wearable and experience-sampling study

Light supports circadian regulation and is associated with non-communicable diseases, yet ocular exposure patterns remain poorly understood. We recruited 191 adults across nine sites in seven countries, combining diaries and contextual reports with near-eye (141 participants; 816 participant-days) and complementary chest-level measurements (154 participants; 902 participant-days). In near-eye analyses, only 24.0% of recorded daytime minutes met the recommendation of at least 250 lx melanopic equivalent daylight illuminance; 63.3% of pre-sleep and 87.7% of bedside sleep-environment minutes met their respective limits. Variation among people and days within sites exceeded that among sites (ratio 1.99; 95%-CI, 1.29-4.77). In hourly models, light source and setting contributed the largest shares of fitted variation after time of day. Site-average outdoor exposure was 9.35 times that while awake at home (95%-CI, 6.95-12.59; 714.2 versus 76.4 lx). This baseline identifies a daytime exposure gap and supports testing interventions in everyday settings to improve light exposure and health.

physiology↗

bioRxiv2023

Beyond Lux: Methods for Species and Photoreceptor-Specific Quantification of Ambient Light for Mammals

BackgroundLight is a key environmental regulator of physiology and behaviour. Mistimed or insufficient light disrupts circadian rhythms and is associated with impaired health and well-being across mammals. Appropriate lighting is therefore crucial for indoor housed mammals. The most commonly used measurement for lighting is lux. However, this employs a spectral weighting function based on human perceived brightness and is not suitable for non-visual effects of light or use across species. In humans, a photoreceptor-specific (-opic) metrology system has been proposed as a more appropriate way of measuring light. ResultsHere we establish technology to allow this -opic measurement approach to be readily extended to any mammalian species, accounting for differences in photoreceptor types, photopigment spectral sensitivities, and eye anatomy. Since measuring photopigment spectral sensitivity can be hard to derive for novel animals and photoreceptors, we developed a high-throughput, easy-to-use, method to derive spectral sensitivities for recombinantly expressed melanopsins and use it to establish the spectral sensitivity of melanopsin from 12 non-human mammals. We further address the need for simple measurement strategies for species-specific -opic measures by developing an accessible online toolbox for calculating these units and validating an open hardware, low-cost, multichannel light sensor for point and click measurement. We finally demonstrate that species-specific -opic measurements are superior to photopic lux as predictors of physiological responses to light in mice and allow ecologically relevant comparisons of photosensitivity between species. ConclusionOur study demonstrates that measuring light more accurately using species-specific -opic units is superior to the existing unit of photopic lux and holds the promise of improvements to the health and welfare of animals, scientific research reproducibility, agricultural productivity, and energy usage.

neuroscience↗