Bright Light Research Articles

Patient-Reported Outcomes in RLBP1 Retinal Dystrophy: Longitudinal Assessment in a Prospective Natural History Study.

To evaluate the performance of two non-disease-specific patient-reported outcome (PRO) instruments, the National Eye Institute Visual Function Questionnaire-25 (VFQ-25) and the Low Luminance Questionnaire (LLQ), in patients with retinaldehyde-binding protein 1 retinal dystrophy (RLBP1 RD). PROs were assessed using the VFQ-25 and LLQ. Rasch analysis was conducted to estimate person and item measures of the VFQ-25 and LLQ questionnaires to determine the association between the two PROs. In addition, the association between these two instruments and their correlations to weighted measures of visual function and disease progression were analyzed in this three-year PRO-focused sub-study of a five-year prospective natural history study. Forty-two patients participated, with most of them having completed at least two PRO follow-up visits at least one year apart. The mean VFQ-25 scores were lowest for distance activities (39.2-49.0) and peripheral vision (37.5-52.4), with mean LLQ subscale scores generally low (<41), except for the emotional distress subscale. Using Rasch analysis, calibrated item and person measures along with their standard errors were estimated for both ePROs. This indicated that the distribution of the VFQ-25 and LLQ item measures well covered the distribution of person function in this group. This suggests that the item difficulties well cover the person-level performance in this population. As well, the two PROs showed a strong and significant correlation at all assessed time points as assessed with Pearson correlation coefficient (0.81, 0.91, 0.81 and 0.87 at baseline, 1/1.5, 2/2.5 (P < 0.001) and 3/3.5 years (P = 0.002)). The composite scores of both PRO questionnaires strongly correlated with clinical measures of visual function. At 2 to 2.5 years of follow-up, meaningful statistically significant declines in peripheral vision (both VFQ-25 and LLQ), distance vision (VFQ-25), and extreme lighting in dark and bright light (LLQ) subscales were noted. This study demonstrated a strong association between VFQ-25 and LLQ scores and their association with clinical measures of visual function. PRO instruments can provide insights into the specific disabilities of this unique patient population and help to guide appropriate outcome measures for future clinical trials.

Optimized Scintillation Imaging in low dose rate and bright room light conditions.

To develop a robust method for non-contact surface dosimetry during Total Body Irradiation (TBI) that uses an optimally paired choice of scintillator material with camera photocathode and can work insensitively to the normal ambient room lighting conditions (~500 Lux). &#xD;Approach: This goal was approached by assessing the emission contrast of scintillator signal to background room ratio (SBR) detected by the camera, in the challening conditions of low dose rate TBI with high room lights. A total of 9 fast-response scintillators, 3 wavelength shifters, and 2 camera photocathodes were systematically tested to determine the optimal combination. The effects of room lights on the scintillator signal and the background signal were assessed to avoid signal saturation while retaining accurate dose measurement. A bandpass wavelength filter was then applied to reduce the effects on room lights and scintillator signal.&#xD;Main Results: One scintillator (EJ262) combined with a blue-green sensitive photocathode camera and a 500nm band pass filter produced the greatest available scintillator SBR of 95 with maximal room lights on. The caveat is that this design rejects all patient Cherenkov light, which can be useful for visualizing the patient treatment. Another option which retained the Cherenkov signal but produced less available scintillator signal was found with another scintillator (EJ-260) and a red photocathode camera with SBR of 35, but a narrow bandpass filter is required to make it work in ambient room lights, which addition will also remove most of the Cherenkov signal. &#xD;Significance: Non-contact scintillator imaging can be used for surface dosimetry in TBI with appropriate pairing of scintillator emission spectrum and camera photocathode sensitivity or optical filtering range.&#xD.

The effect of restricted and free-living conditions on light exposure and sleep in older adults

ABSTRACT During the COVID-19 pandemic, studies reported that restricted living conditions were associated with worse subjective sleep quality. This effect might have been caused by reduced light exposure during lockdowns. We investigated light exposure levels, subjective and objective sleep and physical activity levels in older adults during restricted and free-living conditions after the pandemic. Ninety-one participants (62.7 ± 8.4 years) recruited from the community using social media with 44 participants (63.4 ± 8.9 years) completed follow-up during free-living conditions. Participants wore an actigraphy device and completed sleep diaries for 7 days during each condition. Light values were extracted in hourly bins across the 24-h period and objective and subjective sleep were compared between the conditions. There was an increase in mean 24-h light exposure during restricted-living (1103.7 ± 1024.8 lux) compared to free-living (803.0 ± 803.6 lux; p < 0.001). This was partially related to participants spending 18 min more in bright light conditions (>1,000 lux) during wakefulness in restricted living (2.6 ± 1.9 h) compared to free-living (2.3 ± 2.0 h; p = 0.036). Despite differences in light exposure, there were no significant differences in objective and subjective sleep parameters between the two conditions. More research is required to better understand behaviours related to light exposure and how this may impact on sleep.

Analisis Penataan Perpustakaan untuk Meningkatkan Minat Baca di Sekolah Negeri 1 Demulih

This study aims to analyse the arrangement of the library to increase reading interest in State School 1 Demulih. The arrangement of the library in SD N 1 Demulih has not been fully implemented based on the flow of the library layout to facilitate and process the work done by the library staff, the library layout can attract students' interest in reading. This study uses a descriptive research method with a qualitative method. The data collection techniques used in this study are observation sheets and interview list sheets conducted at SD N 1 Demulih. The results of this study is the Library at SD N 1 Demulih have carried out several strategies for physical and non-physical arrangement of the library. The physical arrangement strategy that has been carried out is the location of the Library that is accessible to students, bright lighting and available air ventilation as well as providing facilities and infrastructure such as chairs and tables in good condition that can be used by students when reading the library collection. Providing these strategies is very important for readers so that students who read in the library feel comfortable and make them feel at home so that the students want to come back again to read.

Arthur M. “Andy” Horne: Leader, Bright Light, and Bully Buster

Arthur M. “Andy” Horne: Leader, Bright Light, and Bully Buster

Increases in Night Lights Intensity Reveal Extreme Events: A Case of Study on the Ongoing Conflict in Ukraine

Abstract. Analyzing night lights images allows identifying and monitoring affected areas during conflicts, as an overall decrease in brightness indicates abandoned or destroyed buildings, curfews, or power shortages. While detecting decrease in lights intensity is an established technique to identify critical areas during conflicts, the causes of appearing bright lights have not been extensively studied. An increase in brightness may be related to extreme events, such as fires resulting from bombing. This paper shows several examples supporting this new use of these images, validated using high-resolution optical earth observation data and ancillary information sources in the frame of the conflict in Ukraine which has been ongoing since February 2022.

An update on the pharmacotherapy of postpartum depression.

Extensive research has been conducted on postpartum depression (PPD) over the past century, and yet no definitive answer regarding its etiopathogenesis, risk factors, genetic predilection, and treatment has been found. The few preclinical and clinical studies propose that maternal brain adaptations to the endocrinological, immunological, and behavioral changes and external sociodemographic risk factors in the perinatal period make women more vulnerable to anxiety and depression. Irrespective of the cause, a dilemma exists regarding the type of help to provide postpartum mothers. With very few treatment options at our disposal, deciding between psychotherapy, pharmacological, and non-pharmacological therapy on a case-by-case basis is unproductive because in developing countries infrastructure is limited and the availability of medications, especially for psychiatric illnesses, is still evolving. Hence, regardless of psychotherapy, antidepressants remain the first line of treatment with selective serotonin reuptake inhibitors (SSRIs); sertraline has the best efficacy and safety profile in breastfeeding women. As endocrine factors play a significant role in etiopathogenesis, hormonal therapy with oxytocin has been shown to be efficacious, and studies investigating the role of testosterone in treating PPD are also under way. In 2019, the US Food and Drug Administration (FDA) approved the first and only drug for the sole purpose of treating PPD, brexanolone. Zuranolone, a drug recently approved by the FDA, has a similar mechanism of action to brexanolone. For breastfeeding mothers reluctant to use pharmacotherapy, somatic therapy has been studied, including bright light therapy, vagal nerve stimulation, and newer noninvasive interventions. This article encompasses a short note on PPD, including its etiopathogenesis and clinical characteristics, and recapitulates the various available and evolving pharmacological and nonpharmacological therapies.

Structure-Photoluminescence Relationship in Ce3+-Doped K5Y(P2O7)2 and Its Sensitization to Dy3+ with Enhanced White Light Emission.

From a fundamental point of view, the structure-photoluminescence relationship is vitally important for developing efficient phosphors and rationally improving their performances. In this work, Rietveld refinements on high-resolution powder X-ray diffraction (XRD) data were conducted to verify the Ce3+ distribution in K5Y(P2O7)2 (KYPO). Ce3+ ions are located at both M1 and M2 sites, with occupation factors of 0.31(2) and 0.19(2), respectively. Importantly, the crystal field strength (CFS) is stronger at the former site due to the larger bond valence sum. Correspondingly, the Ce3+ emission can be deconvoluted into four Gaussian-type bands centered at ∼353, ∼383, ∼343, and ∼369 nm, where the former two belong to Ce3+ at the M1 site and the latter two are assigned to Ce3+ at the M2 site. Ce3+ in KYPO is a highly efficient activator, with optimal internal and external quantum efficiencies of 98.9 and 74.6%, respectively, and was thus utilized to sensitize the Dy3+ emission. Indeed, energy transfer from Ce3+ to Dy3+ was confirmed by fluorescent decay curves for Ce3+/Dy3+ codoped KYPO, and the mechanism was supposed to be dominated by dipole-dipole interactions. Indeed, it can be pumped by a 310 nm LED chip and emits a bright white light. Ce3+ photoluminescence exhibits high resistance to thermal quenching, and it can be further enhanced by codoping Dy3+, i.e. the emission intensity remains 96.3% at 423 K.

Light source dependence on quantitative measurement for dispersibility of dark-colored colloidal dispersions

Abstract Colloidal particles are applied to manufacturing in various fields such as ink, food, and cosmetics etc. It is important to study about the dispersibility of colloidal particles because they are dispersed in some solvents. However, many of colloidal dispersions are dark colored and typical methods cannot evaluate the dispersibility. Therefore, dispersibility has been evaluated by naked eyes in almost all research papers. Therefore, we have fabricated quantitative dispersibility evaluation system (QDES) for the dark colloidal dispersion using light transparency by various light types and colors of bright lights. The obtained data were fitted with a stretched exponential function (SEF) to evaluate the dispersibility. As one of the examples of a dark colloidal particle, we chose graphene oxide (GO) which is applied to manufacturing with printing technology. From the measurement results, the red LED light is suitable for the QDES in terms of accuracy and applicability to the SEF.

The evaluation of an eHealth tool to prevent and alleviate migraine complaints in adults

Abstract Background Migraines attacks cause great suffering in individual patients. There is great unfulfilled potential to increase patients’ knowledge about various personal triggers and subsequent treatments. The objective of this study is to pilot test an e-Health tool that aims to increase migraine patients’ knowledge. It takes into account personal preferences and contributes to informed decision-making in choosing the appropriate method. Considering the shortage of primary care physicians and other health care providers, such an e-Health tool could be of great value. Methods lessmigraine.nl consists of a website with information plus an electronic decision aid. It was evaluated on its content, development process and effectiveness, and its contribution to the patients’ empowerment process. A first round of usability testing was done using semi-structured interviews and thematic analysis with 12 patients from a Dutch General Practice until data saturation. After minor improvements to the e-tool, in a first implementation step subsequently 85 patients used the e-tool. Results Patients’ expectations were exceeded in terms of the content of the e-Health tool, as all patients discovered new potential migraine triggers. Most patients found the tool effective in the sense that it provided enough information to decide on an appropriate treatment. The implementation was successful in the sense that all 85 participants completed the e-tool. Most important triggers were stress, sleeping problems, changes in weather and flickering or bright light. Conclusions The majority of the migraine patients were satisfied with the e-Health tool. It enlarged their knowledge of prevention and treatment options and therefore empowered them in their decision-making process and communication with their GP. Other aspects of implementation need to be studied. This study needs to be repeated in other clinical settings. Key messages • Migraines cause great suffering in individual patients: Considering the shortage of primary care physicians and other health care providers, an e-Health tool could be of great value. • The e-Health tool increases patients’ knowledge about migraine, including personal triggers and subsequent treatments.

Structural Design of Hybrid Manganese(II) Halides for High Quantum Efficiency and Specific Response to Methanol.

Manganese(II) halides have been a new generation of optoelectronic materials due to their fascinating luminescent properties, however, lacking specific solvent-responsive analogues with high quantum efficiency. Herein, we prepared three single crystals, [Pr(MIm)2][MnBr4] ([Pr(MIm)2]2+ = 1,3-di(methylimidazolium)-propane, Compound 1), [Pr(EIm)2][MnBr4] ([Pr(EIm)2]2+ = 1,3-di(ethylimidazolium)-propane, Compound 2), and [Bu(MIm)2][MnBr4] ([Bu(MIm)2]2+ = 1,4-di(methylimidazolium)-butane, Compound 3), where different Bola-type cations were chosen as organic components to separate [MnBr4]2- tetrahedrons. All three compounds emitted bright green light with excellent quantum yields of 95.3, 80.0, and 96.2%, benefiting from the large Mn···Mn distance. More interestingly, Compound 3 showed a highly selective response to methanol in a series of tested organic solvents, with a rapid and reversible change in emission color from green to red. The single crystal of [Bu(MIm)2][MnBr4]·CH3OH with red emission proved that the luminescence switching was attributed to the adsorption of CH3OH molecules into the lattice space in the form of the O-H···Br hydrogen bonds. To our knowledge, for tetrahedrally coordinated Mn(II) species, the reversible emission color switching between green and red triggered by a solvent without the change of coordination number is achieved for the first time, providing promising applications for the specific detection of methanol.

Circadian re-set repairs long-COVID in a prodromal Parkinson’s parallel: a case series

BackgroundIn this case series, results from daily visual exposure to intense polychromatic light of 2000 to 4000 LUX is presented. Bright light treatment is a standard procedure for treating seasonal affective disorder and prodromal Parkinson’s disease with high success. With the post-encephalitic symptoms of long-COVID closely approximating those of prodromal Parkinson’s disease, we treated insomnia and sleep-related parameters in these patients, including total sleep, number of awakenings, tendency to fall back to sleep, and fatigue, to determine whether mending sleep could improve quality of life.Case presentationWe present three female and two male Caucasian patients aged 42–70 years with long-COVID that persisted from 12 weeks to 139 weeks after contracting coronavirus disease.ConclusionA light presentation protocol was adapted for long-COVID that not only restored sleep in all patients, but also unexpectedly repaired the depression, anxiety, and cognitive changes (brain fog) as well. A robust pattern of recovery commencing 4–5 days after treatment and was maintained for weeks to months without relapse. These preliminary findings represent a novel, minimally invasive approach for managing the most debilitating symptoms of long-COVID, making it an ideal candidate for the drug hypersensitive, post-encephalitic brain. That a compromised circadian mechanism seen in Parkinson’s disease may also underlie post-encephalitic long-COVID implicates a compromised role of the circadian system in these disorders.

Defect-Enabled Superior Negative Thermal Quenching in Palmierite Ba9La(VO4)7:Eu3+ for WLED In Situ Temperature Measuring.

Negative thermal quenching (NTQ) of the phosphors is critically important for both scientific research and practical applications, but the design of efficient NTQ phosphors is still a challenging task. Herein, we report a new strategy for developing NTQ materials by cation-vacancy engineering. Specifically, a new color-tunable Ba9La1-x(VO4):xEu3+ (BLVO:xEu3+) phosphor with abundant intrinsic cation vacancy was developed, exhibiting superior NTQ behavior under 365 nm excitation. The NTQ performance can be modulated via adjusting Eu3+ doping levels, and the emission intensity of Eu3+ ions in the BLVO:0.20Eu3+ phosphor increased by 275% at 473 K compared to room temperature. Furthermore, the reported material emitting bright white light under 365 nm excitation was well-suited for use in white light-emitting diode (WLED) phosphor and fluorescent temperature sensors, exhibiting outstanding color-rendering index (90.1) in lighting and high sensitivity (Sa = 11.83% K-1, Sr = 2.33% K-1) in temperature detecting. Lastly, the operating temperature of WLED at different currents can be monitored and displayed in real time through emission spectroscopy. All of the results demonstrated that the designed NTQ BLVO:xEu3+ can be used as a single-phase white phosphor and optical thermometry. This work provides a fresh perspective for designing high-efficient NTQ phosphors and expands the application of phosphors in WLED in situ temperature detection.

High color rendering index WLEDs enabled by multi-band tuning of InP quantum dots

Quantum dots (QDs) represent a significant class of fluorescent materials, offering the potential to reduce power consumption and enhance the color rendering index (CRI) of white light-emitting diode (WLED) devices. However, the presence of toxic elements such as Cd and Pb in traditional fluorescent QDs limits their widespread commercial application. Compared to the broad emission characteristics of environmentally friendly AgInS2 and CuInS2 QDs, the narrower linewidth of InP-based core-shell QDs is advantageous for developing WLED devices with a higher CRI. In this study, we employed a multistage heating method to synthesize a series of amino-phosphine-based InP/ZnSe core-shell QDs, which exhibited emission wavelengths ranging from 535 to 650 nm, narrow emission linewidths of 43-47 nm, and high photoluminescence quantum yields of 60%-80%. Subsequently, six different color QDs are used to fabricate a WLED device. The best WLEDs show not only bright warm light (correlated color temperature = 3323 K) with a maximum luminous efficacy of 74.1 lm W-1, but also excellent color quality (CRI Ra = 93, as well as R9 = 94.8, and R13 = 97.1). These results indicate remarkable progress in InP-based WLEDs for high-quality lighting applications.

Differentiated Impacts of Indoor and Outdoor Fitness Environments on Residents’ Activity Intensity: A Perspective on Homo Urbanicus

This study develops a framework for the impact mechanism based on the “homo urbanicus” theoretical perspective, linking indoor and outdoor fitness environmental elements to residents’ subjective perceptions and their activity intensity. An empirical investigation is conducted using structural equation modeling (SEM) with data from 286 valid questionnaires (N = 421). The results demonstrate that both indoor and outdoor fitness environmental elements—specifically spatial, facility, and environmental factors—significantly positively influence residents’ fitness activity intensity, with this relationship mediated by perceptions of safety, convenience, comfort, and aesthetics. Furthermore, the study uncovers variations in the types and degrees of influence across indoor and outdoor settings. Based on these findings, the author proposes several planning and design strategies: “In indoor environments, it is essential to ensure that fitness spaces feature bright lighting and thoughtful design to enhance aesthetic appeal; additionally, optimizing spatial layouts and integrating information services can foster greater social interaction. For outdoor environments, prioritizing locations near aesthetically pleasing architecture, adjacent to blue landscapes, and within open areas, as well as sites that are close to community amenities and abundant surrounding facilities, will enhance residents’ fitness activity intensity”.

Pd-Catalyzed Dual C-H Activation/Cyclization: Convergent and Divergent Synthesis of 1-Azahelicenes.

Herein, we report a convergent synthesis of 1-azahelicenes using easily available quinoline derivatives and cyclic diaryliodonium salts as starting materials. This reaction undergoes a palladium-catalyzed dual C-H activation/cyclization process to give facile access to a wide range of 1-aza[5]helicenes and 1-aza[6]helicenes with abundant functional groups (including F, Cl, Br, I, CF3, SeR, SR, and heteroaryl) in moderate to excellent yields, thereby providing new opportunities to fine-tune the properties of the helicene backbone. In addition, the obtained products could be further transformed into helicene-based Lewis base catalysts and redox switch materials easily. Notably, one selected 1-azahelicene shined bright yellow light by aggregation. These features enlarge the chemical space of 1-azahelicenes and inspire further utilization in other areas of research.

The Management and Prevention of Delirium in Elderly Patients Hospitalised in Intensive Care Units: A Systematic Review.

Delirium or an acute confusional state (ACS) is characterised as being a frequent and complex hospital complication in older adult patients, which can affect their level of independence and increase patient morbidity and mortality. Critically ill patients in the intensive care unit (ICU) frequently develop ICU delirium, leading to longer hospital and ICU stays, increased mortality and long-term impairment. This review aims to assess existing evidence of interventions that can be considered effective for the management and prevention of delirium in ICUs, reducing short-term morbidity and mortality, ICU and hospital admission times and the occurrence of other long-term complications. For this systematic review, we searched Medline, PubMed, Cochrane Library, CINHAL, LILACS, SciELO and Dialnet from January 2018 to August 2024, in English, Spanish and French. MeSH descriptors were adjusted to search the different databases. We also checked Prospero for ongoing systematic reviews. The electronic search yielded a total of 2656 studies, of which 14 trials met the eligibility criteria, with a total of 14,711 participants. We included eight randomised clinical trial (RCTs), four cohort analyses, one systematic review and one observational trial, including participants over 65 years admitted to the ICU. Ten of these studies were based on pharmacological interventions, three of them examined non-pharmacological interventions and the remaining study examined mixed (pharmacological and non-pharmacological) interventions. Six placebo RCTs were included, plus four reported comparisons between different drugs. Regarding non-pharmacological interventions, nursing programmes focused on optimising modifiable risk factors or the use of therapies such as bright light are emerging. Regarding mixed interventions, we found the combination of invasive techniques and with sedoanalgesia. Due to its satisfactory level of sedation, dexmedetomidine is presented as a viable option because, although olanzapine offers safer results, postoperative administration angiotensin inhibitor systems significantly reduced the incidence of delirium. As for propofol, no significant differences were found. Among the non-pharmacological and mixed therapies, bright light therapy was able to reduce the incidence of delirium, and the combination of epidural/general anaesthesia was effective in all subtypes of delirium. Concerning the remaining interventions, the scientific evidence is still insufficient to provide a definitive recommendation.

Carbon Dots Prepared by One-step Sintering Method and their Application for pH Detection

Introduction: In recent years carbon dots (CDs) have attracted researchers due to their unique physicochemical and fluorescent (FL) features, which can be applied in many fields such as battery materials, fluorescence sensing, display, biological imaging and photocatalysis. Method: We prepared CDs by using a facile one-step sintering method. The fluorescent properties and the application of pH detection were measured and analyzed. Results: The results show that CDs emit bright purplish-blue light centred at 425 nm excited by 355 nm UV light. FL intensity shows a linear relationship with pH values at 1~4 and 7~11, respectively. The reasonable mechanism of the tested effective pH sensitivity is discussed. Conclusion: Our study shows that the CDs prepared by the one-step sintering method have great potential to be used as pH sensors for physiochemical measurements.

Reduced neurovascular coupling of the visual network in migraine patients with aura as revealed with arterial spin labeling MRI: is there a demand-supply mismatch behind the scenes?

BackgroundAlthough neuroimaging investigations have consistently demonstrated that “hyperresponsive” and “hyperconnected” visual cortices may represent the functional substrate of cortical spreading depolarization in patients with migraine with aura, the mechanisms which underpin the brain “tendency” to ignite the cortical spreading depolarization and, consequently, aura phenomenon are still matter of debate. Considering that triggers able to induce aura phenomenon constrain brain to increase global (such as physical activity, stressors and sleep abnormalities) or local (such as bright light visual stimulations) energy demand, a vascular supply unable to satisfy the increased energy requirement could be hypothesized in these patients.MethodsTwenty-three patients with migraine with aura, 25 patients with migraine without aura and 20 healthy controls underwent a 3-Tesla MRI study. Cerebral blood flow and local functional connectivity (regional homogeneity) maps were obtained and registered to the MNI space where 100 cortical regions were derived using a functional local-global normative parcellation. A surrogate estimate of the regional neurovascular coupling for each subject was obtained at each parcel from the correlation coefficient between the z-scored ReHo map and the z-scored cerebral blood flow maps.ResultsA significantly higher regional cerebral blood flow across the visual cortex of both hemispheres (i.e. fusiform and lingual gyri) was detected in migraine with aura patients when compared to patients with migraine without aura (p < 0.05, corrected for multiple comparisons). Concomitantly, a significantly reduced neurovascular coupling (p < 0.05, false discovery rate corrected) in the primary visual cortex parcel (VIS-4) of the large-scale visual network was observed in the left hemisphere of patients with migraine with aura (0.23±0.03), compared to both patients with migraine without aura (0.32±0.05) and healthy controls (0.29±0.05).ConclusionsVisual cortex neurovascular “decoupling” might represent the “link” between the exposure to trigger factors and aura phenomenon ignition. While physiological vascular oversupply may compensate neurovascular demand-supply at rest, it becomes inadequate in case of increased energy demand (e.g. when patients face with trigger factors) paving the way to the aura phenomenon ignition in patients with migraine with aura. Whether preventive treatments may exert their therapeutic activity on migraine with aura restoring the energy demands and cerebral blood flow trade-off within the visual network should be further investigated.

Light Exposure on Alertness after Wake-Up in Healthy Men: Comparing Dim, Bright, Red, and Blue Light

Introduction: Light is a key factor in moderating human alertness, both subjective and objective. However, the methodology applies in research on the effects of exposure to light of different wavelengths and intensities on objective and subjective alertness varies greatly and evidence on objective alertness in particular is still inconclusive. Thus, the present, highly standardized within-subject laboratory study on N = 44 healthy males explored how LED light of different intensities (dim vs. bright light) and wavelengths (red vs. blue) affected objective (reaction time/RT) as well as subjective (sleepiness) alertness in the morning after wake-up. Methods: Participants spent two separate nights in the laboratory and were exposed to either one of the two light intensities or colors for 60 min after wake-up. Additionally, they indicated their sleepiness on the Karolinska Sleepiness Scale and participated in an auditory RT task before and after light intervention. It was hypothesized that both bright and blue light would lead to greater subjective and objective alertness when compared to dim and red light, respectively. Results: Results indicated that average RTs were longer for participants in the bright light condition (p = 0.004, f2 = 0.07) and that RTs decreased post-light exposure irrespective of light being dim or bright (p = 0.026, f2 = 0.07). However, dim versus bright light and RT did not interact (p = 0.758, f2 = 0.07). Chronotype was a significant covariate in the interaction of dim versus bright light and subjective sleepiness (p = 0.008, f2 = 0.22). There was no difference in RTs when comparing exposure to red or blue light (p = 0.488, f2 = 0.01). Findings on subjective sleepiness and light of different wavelengths revealed that sleepiness was reduced after light exposure (p = 0.007, f2 = 0.06), although the wavelength of light did not appear to play a role in this effect (p = 0.817, f2 = 0.06). Conclusion: Hence, neither of the hypotheses could be confirmed. However, they indicated that evening types might benefit from exposure to bright light regarding sleepiness, but not morning types.