This study compared five wearable sensors (VEET, Clouclip, Actiwatch, ActLumus, and GENEActiv) for quantification of myopia-related environmental exposures. Thirty participants (27.8 ± 7.0 years) simultaneously wore two spectacle-mounted and three wrist-worn sensors for one day while maintaining a detailed activity log. Data were binned by viewing distance (near: 15– < 60 cm, intermediate: 60– < 100 cm, far: ≥100 cm) and illumination (scotopic: <3 lux, mesopic: 3 to < 30 lux, indoor photopic: 30 to <1000 lux, outdoor photopic: ≥ 1000 lux). The VEET recorded significantly more near and intermediate time than the Clouclip (p < 0.001). Activity logs yielded significantly lower near viewing compared to the VEET (p < 0.001) and Clouclip (p = 0.048) and higher intermediate viewing time (p < 0.001). All sensors demonstrated excellent agreement for categorizing outdoor illumination. Activity logs reported significantly greater outdoor durations compared to the VEET, Clouclip, GENEActiv and Actiwatch (p < 0.05 for all). The Actiwatch recorded significantly greater scotopic ( < 3 lux) durations compared to other sensors (p < 0.05 for all). While subjective logs provided useful contextual information, visual activity estimates were significantly different than objective measures. Small but significant discrepancies across sensors emphasize the importance of device selection in myopia research.
Abstract Daily light exposure is temporally structured, yet calibrated spectral measurements are usually available only at selected locations and times. Turning such a sparse library into a schedule-resolved profile requires an assignment rule: a decision about which measurements may represent each unmeasured part of the day. We examined how much that decision matters. Sixty-three eye-level spectral irradiance measurements, collected across home, commute, office and lunch settings on three June days in Ottawa, were mapped onto a schedule of 22 half-hour slots. For each of six assignment rules we generated 100,000 profiles and computed melanopic dose and time above thresholds of 250, 1,000 and 10,000 melanopic lx. Indoor-only and outdoor-only assignments gave contrasting bounds, with median doses of 16,536 and 119,995 lx ⋅ h. Among the four rules that combined indoor and outdoor measurements, median dose varied only from 44,257 to 48,337 lx ⋅ h, whereas the central 95% of the generated dose distributions spanned ranges differing by nearly a factor of two. Central estimates were set largely by the composition of the eligible measurement pools rather than by the structure a rule preserved; the rule mainly determined spread. Targeted substitutions, in which only commute and lunch conditions were changed, raised median dose by 28,600 lx ⋅ h, with outdoor lunch contributing more cumulative dose and outdoor commuting more time above 10,000 lx. The framework supports sensitivity and scenario analysis rather than reconstruction of continuous personal exposure, and shows why the assignment step must be reported explicitly for a constructed profile to be interpretable.
Abstract Guidelines for light measurement in laboratory studies of the non-visual effects of light have recently been put forward. Yet, outside of controlled environments, unique challenges necessitate additional consideration and modifications to those recommendations. The purpose of this paper is to build on prior work by outlining pre-ocular, ocular, and post-ocular factors and associated considerations that influence photic exposure and the physiological effects of light in the field. Practical constraints of applying laboratory measurement guidelines and tools and strategies for light measurement in field-based work are discussed in detail, including the trade-offs of different approaches. A standard operating procedure for measuring light in field studies is provided, with particular attention to managing sources of variability, along with an example that applies the procedure to a recent study. Finally, future directions and remaining challenges of photic measurement during field studies of sleep, circadian rhythms, and other non-visual effects of light are identified.
Abstract Growing evidence from epidemiological and lab-controlled studies links night shift work to adverse health outcomes, but evidence from real-world occupational environments remains limited. Using multiple wearable devices and mobile health apps, alongside other objective and subjective assessment tools, we assess nutritional intake and cardiometabolic parameters among 72 shift workers recruited from a single-center Swiss hospital (82% female; median age 31 years; body mass index 22.7 kg/m 2 ) during three consecutive night shifts and three consecutive day shifts. While intake of calories, protein, and fat is reduced during night shifts, glycemic variability and postprandial glucose spikes are increased compared to day shifts. After three consecutive night shifts, plasma cortisol is reduced, and the 24-h heart rate and heart rate variability are altered. Exploratory analysis reveals higher protein intake correlates with lower glycemic variability, whereas nighttime eating is associated with increased glycemic variability. Future interventional studies should explore whether adjusting meal composition and timing could improve glycemic variability in night shift workers.
Prolonged light exposure and rest-activity alteration are increasingly prevalent in modern society, yet their health consequence and the underlying mechanism remain poorly characterized. The liver is an organ central to metabolic and circadian regulation. We hypothesized that extended wakefulness, which was modeled as long photoperiod in humans and short photoperiod in nocturnal mice, would affect liver integrity and function. Actigraphic watch, wheel running, morphological, biochemical, transcriptomic, and chromatographic techniques were employed to examine the impact of light exposure alteration. To reverse the circadian disorders mediated by the sympathetic nervous system (SNS) activation, SNS inhibitor or time-restricted feeding was applied. In both humans and mice, extended wakefulness increased daily activity and reduced rest, as well as inducing tissue injury exclusively in the liver and predominantly affecting bile acid metabolism. Mechanistically, short photoperiod enhanced hepatic sympathetic innervation and activity in mice, activating a norepinephrine–β2-adrenergic receptor–protein kinase A signaling axis that reprogrammed the hepatic circadian clock and bile acid metabolism. Chemical sympathectomy not time-restricted feeding restored bile acid rhythmicity and alleviated liver injury. These findings identified the liver as a primary target of circadian disruption and established elevated sympathetic tone as a key mediator linking extended light exposure to metabolic dysfunction.
