https://orcid.org/0000-0003-2736-7171
Figures
Abstract
Bright daylight has various positive influences, such as the long-term synchronization of circadian rhythms and an associated alertness that creates optimal conditions for attentional performance. However, the short-term effects of light on attention have not yet been sufficiently researched. Studies of these short-term effects on selective attention also showed partly contradictory effects. To investigate these short-term effects, 95 participants completed the Attention Network Test, under conditions of bright daylight or warm-white light. The focus of the present study was on executive attention, because this construct comes closest to the ANT short form of selective attention used. A significant enhancement of executive attention was observed under bright daylight conditions. This specifically means a short term effect of bright daylight on executive attention and thus selective attention in young adults.
Citation: Wessolowski N, Rahim RJ (2025) Is executive attention affected by environmental lighting conditions? PLoS ONE 20(1): e0305998. https://doi.org/10.1371/journal.pone.0305998
Editor: Michael B. Steinborn, Julius-Maximilians-Universität Würzburg: Julius-Maximilians-Universitat Wurzburg, GERMANY
Received: June 8, 2024; Accepted: December 18, 2024; Published: January 6, 2025
Copyright: © 2025 Wessolowski, Rahim. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: All relevant data are within the manuscript and its Supporting Information files.
Funding: The author(s) received no specific funding for this work.
Competing interests: The authors have declared that no competing interests exist.
1. Introduction
Natural sunlight affects humans, both physiologically and psychologically. Sunlight synchronizes the “internal clock,” influencing, among others, our sleep-wake cycle, mental energy, pleasure, motivation, and attention [1]. Therefore, artificial daylight is used indoors, to optimize room lighting or as a specific intervention in light therapy. Although field and laboratory studies have shown positive effects of intense artificial daylight on attention in different populations and under different conditions compared to neutral and warm white light and dimmed illuminance levels [2–9], not all investigations have yielded significant effects [2].
However, these empirical findings can only be explained theoretically to a limited extent, because the mechanism of light interventions during the day are still the subject of controversy [3, 9]. This is especially true for short-term light interventions lasting only a few minutes during the day. Even those studies that point beneficial artificial light effects [4, 8] have yielded heterogeneous results on individual subscales of the frequently administered d2 test of attention [10]: Increase in the speed-based total value (KL) vs a reduction in the error rate (F). Among the various possible causes underlying the diversity of extant findings, methodological differences in rather global forms of assessment of the construct of attention, particularly deserve closer consideration. The present study, therefore, investigates the effects of daylight on executive attention by employing an established and highly robust method resistant to confounders.
1.1 Pathways of the effect of light on human behavior
Regarding the general effects of light on human behavior, three different explanations are currently discussed [4, 9].
1.1.1. Visual pathway.
In the retina light hits the retinal cones responsible for the perception of color and the retinal rods responsible for the perception of brightness; these impressions are then transmitted through the ganglion cells and through the optical nerve to reach the visual center in the occipital lobe, where a visual impression emerges [11]. An increase in illuminance results in an improvement in visual perception by means of increased brightness and color contrasts [12], which can in turn counteract visual impairments to some degree [13]. In addition, increased illuminance can also alleviate signs of fatigue as well as eye pain and headaches [12, 13]. In the present study, this explanation is the visual pathway less possible. This is due to the absence of any change in the illuminance of the monitor, only that of the environmental condition. Although, ambient lighting can also affect vision on the monitor, but these effects are rather minor and should have a less significant impact in the relatively short experiment. However, the improvement in vision by increasing the illuminance could be partly responsible for the effects of the reference studies that conducted paper-based attention tests.
1.1.2. Neurobiological non-visual pathway.
In addition to the retinal rods and cones, a third type of receptor has been identified at the retina, the intrinsically photosensitive retinal ganglion cells [14–16]. These receptors cover the retina like a spider web and are directly linked to the suprachiasmatic nucleus via the retinohypothalamic tract. This nucleus is the primary clock for all circadian body functions and controls these functions through the hormones melatonin and cortisol as well as the cryptchrome proteins CRY and PER [11]. Melatonin is produced in the pineal gland from the precursor serotonin and is suppressed by light. Cortisol is controlled indirectly through the release of adrenocorticotropic hormone, and its rhythm is roughly opposite that of melatonin release. Furthermore, the exact temporal course of light incidence on the retina, from changes in neuronal and hormonal activity to manifest changes in perception and behavior, is not yet fully clarified. In addition to the duration and intensity of exposure, individual and situational factors play a major factor [17, 18].
1.1.3. Psychological pathway.
Light may yield psychological effects by mechanisms of classical conditioning [19] and mood [17, 18]. For example, dark-warm light like an open fire has been associated with cozy memories, yielding states of relaxation, etc. Dark and cold light, like in the cellar, is paired with unpleasant experiences and reminds one of fear or depression [19]. Bright daylight is linked to activity and creates a mood that increases concentration [17, 18]. Knez [17], for example, showed a connection between light, mood and attention. The results of this study showed that a colour temperature which induced the least negative mood enhanced the performance in the long-term memory and problem-solving tasks that require selective attention.
The mechanisms of the effect of light on immediate experiential and behavioral changes during the day are finally not clear. In addition to the duration and intensity of light exposure, individual and situational factors also interact in light application in everyday life: for example, age and gender [17, 18] as well as anatomical characteristics [1], have an influence on the effect of light as individual factors. Situational factors of light applications include the location, occasion, and setting, as well as the form of the relationship with the people involved [20]. Output arousal may also play an important role in the effect of light on humans, especially in the stress response. A connection between light, attention and arousal was found [21, 22].
Also the exact connection between light as a zeitgeber for circadian functions and immediate changes in short-term behavior during the day has not yet been completely clarified. However, the fact that short-term light interventions during the day also activate brain areas belonging to the circadian system [23] as well as studies have shown that light interventions during the day can influence alpha waves in the brain [24, 25]. The research goal is to find further evidence at the behavioral level for the effect of light during the day.
1.2 Previous studies on the attentional effects of light
While there are fewer studies of high quality in adults, initial controlled studies on the use of artificial daylight in school settings showed that light supports attention in the age group of children and adolescents. For instance, Barkmann, Wessolowski, and Schulte-Markwort [4] examined the effect of artificial daylight on attention-related task performance in the setting of a field study in primary and secondary schools. Among other lighting conditions in variable light, a daylight condition (1060 lx and 6500 K) was compared with a control condition (300lx and 4000K). In a sample of 110 pupils, the concentration performance (CP; number of detected target items minus omission errors searching through lines of characters for prespecified target items) was measured using the d2 test of attention [10] and the ELFE 1–6 [21] as well as the LGVT 6–12 [22] reading tests. Under artificial daylight, there were significantly fewer errors (missed target items and false marked characters) in the d2 test of attention and significantly more words read in the reading tests. No effects were found in the lines processed per time unit (edited target items) and CP of the d2 test of attention.
A supplementary laboratory study by Wessolowski [26] showed comparable results in 95 adult students with significant effects of small size in overall error, omission errors and, contrary to the analogous field study, in working speed.
The first of three experiments of Sleegers, Moolenaar, Galetzka, Pruyn, Sarroukh and van der Zande [8] was a quasi-experimental field study with n = 98 students in grades 4 and 6 (M = 10.0 years) from one elementary school. In total, the d2 test of attention was administered at three different time points (pre-measurement, first post-measurement, second post-measurement) under different light conditions in an intervention and a control group. The interval between pre- and post-measurements was one month, the interval between the two post-measurements one week. In the pre-measurement, the “standard” light program (300lx and 3000-4000K) was used for both groups. In the post-measurements, a daylight program (1000lx and 6500K) was used in the intervention group, while the “standard” light program was used in the control group. The intervention group scored significant better (large effect sizes) on d2 overall error and CP compared to the control group. In the second experiment of Sleegers et al., n = 37 students at the age of 10 years from two schools were examined with otherwise the same procedure, light conditions and measuring instruments as in the first experiment. The results of this second experiment largely replicated those of the first experiment. The third experiment realized a randomized design in a darkened lecture room with a total of n = 55 students from six schools. No significant effects were found in terms of overall error, speed or CP.
The aim of the study by Auras, Barkmann, Niemeyer, Schulte-Markwort and Wessolowski [3] was to test specific light interventions on attention in the Child and Adolescent Psychiatry. Using a quasi-experimental A-B-A-B study design, a daylight programme (A) with high illuminance (5312 K, 793 lx) was tested against a comparative light programme (B; 4081 K, 378 lx). CP, overall errors and working speed of 30 patients (age M = 11.5 years) was assessed using the d2 test of attention of [10] and subjective self-assessment for attention and stress level was recorded using questionnaires. In the d2 test of attention there were significant improvements of medium size under the daylight programme condition in CP and working speed but there were no effects in overall errors. The subjective self-assessments, on the other hand, showed a decrease in concentration and an increase in stress and fatigue under daylight conditions.
Weitbrecht, Bärwolff, Lischke and Jünger [2] investigated the influence of the correlated color temperature of light on concentration and creativity in n = 50 students and employees. The three light scenarios (3000 K, 4500 K, 6000 K) were given with a constant illuminance of 1000 lx in a darkened room by an LED surface area light. Among others, the d2-bq test (short form of d2 test of attention), a creativity test [27], a word test (in which words of a certain category must be recognized in a box with letters) [28] and a logic test [27] were used. The order of the three light scenarios were randomized. In the d2-bq test, no significant differences were found between the light conditions. Under the warm light condition (3000 K), improvements in the creativity test were observed compared to the conditions of 4500 K and 6000 K. Significant advantages in favor of the daylight condition (6000 K) were found in the word test, which also requires attention. In the logic test (also attributed to creativity), the highest performance was achieved at 3000 K compared to 4500 K and 6000 K. Accordingly, the authors conclude that performance improvements were significant in terms of creativity in warm light (3000 K) and in terms of attention in light with higher blue content (4500 K, 6000 K), even though their results failed to reach the level of significance.
In summary, five out of six studies using the d2 attention test found significant effects of bright daylight on concentration performance. While Sleegers et al. [8] found effects both in CP and in the decrease of overall errors, Barkmann et al. [4] only found effects in the decrease of overall errors, Wessolowski [26] found effects in overall errors and working speed and Auras et al. [3] found an increase in CP and no decrease of overall errors.
It should be noted, however, that the performance measures provided by the d2 test are unspecific with regard to the underlying attentional processes and were observed in children and adolescents.
1.3 Questions and hypotheses of the present study
The results of controlled light studies in children and adolescents speak for an effect of daylight on attention. However, participants subjectively report more stress [3] and the objective effects are found on different scales of the d2 attention test. Could this be because of the increase in performance due to daylight at the expense of the perception in stress? Furthermore, controlled light studies in the age group of adults are lacking. Therefore, the present study is intended to clarify more precisely the impact of light on young adults. In addition, this study aims to understand the effect of light on the process of executive attention. Therefore, we analyzed executive attention with the Attention Network Test (ANT) [29] in short form more elaborately than previously tested with the d2 test of attention. The d2 test measures rather broadly and less process-specific. This could also explain the heterogeneous d2 findings of the previous studies. We assume that congruency (executive attention) in the ANT comes closest to the construct of selective attention in the d2 test of attention. The ANT combines two of the classical paradigms of visual attention (i.e., the Posner and Eriksen paradigms). In addition to Executive Function, the ANT incorporates the Orienting and Alerting networks. In principle, light effects can also be expected for these factors [30, 31]; however, the findings are heterogeneous [32, 33], and due to the short duration of the experiment [29], it is possible that these effects may only be minimally detectable or not detectable at all. Fan et al. [29] demonstrated that an enhancement in the performance of executive attention tasks correlates with the activation of the anterior cingulate cortex (ACC) in the human brain. If a discernible light effect is observed in the current experiment concerning executive function, this would provide additional evidence for the biologically non-visual function in short-term light effects and further support for the short-term activation of the circadian system, as both the SCN and ACC are constituents of the limbic system [11]. Based on observations during previous studies [3], we also explicitly surveyed subjective stress perception during light exposure using questionnaires. This is important because stress affects performance. The Yerkes and Dodson law shows an inverted u-shaped relationship. This implies that performance initially rises in proportion to stress, and above a medium level of stress, performance reaches its best value; if stress now continues to rise, this increasingly leads to losses [34].
In sum, the present study aimed to answer the following three questions: 1. Are higher performances in executive attention observed under bright daylight than under dimmed warm light conditions? 2. What effects can be observed in relation to orienting and alerting? 3. Are the two lighting conditions associated with different levels of subjective stress.
2. Materials and methods
2.1 Sample
The sample size was determined by an a-priori power analysis. Using G-Power [35], this showed an optimum sample size of n = 788 with expected small effects and p < .05. Since such a large sample has to be collected over several years in the complex laboratory experiment, the present study monitors the effects after data collection in the first semester.
A sample was recruited from Bachelor and Master students, their families and friends. All n = 91 participants were included in all analyses because there were no missing data. The large proportion of psychology students (75.8%) and the high proportion of women (72.6%) should be accentuated (Table 1). None of the control variables showed any significant correlations with the ANT Outcome (target variables), so that these variables were not included as covariates in the analyses.
2.2 Design and materials
The study took place in the laboratory of the Medical School Hamburg (MSH) in four identical sound insulated and ventilated test cabins (180 cm long and 220 cm high, light grey inner walls). A 72 x 35 cm cabin window was located behind the participants (left of the door). The cabin windows were facing away from the windows of the laboratory room (north-east), so that barely any natural daylight (see control variables) would enter the cabins (maximum value determined over all measurements: 30 lx). The cabins are each equipped with two chairs, one table, one computer, one screen, and two lamps (Figs 1 and 2).
The hardware was a Lenovo PC (Intel (R) Pentium (R) CPU G 3220 @ 3.00 Ghz, RAM: 4.0 GB) with Windows 7 Professional (64 Bit) and a computer monitor with a 22" LCD screen. The ANT (see below) was controlled and presented with the experimental software E-Prime 2.0 (Psychology Software Tools, Inc.).
As illustrated in Fig 1, the lighting for the experimental condition bright daylight was provided by two off-the shelf floor lamps (Ikea Not) which were equipped with two compact fluorescent lamps (one Philips T65 Softone Cool Daylight E27 20W 865 and one Philips Genie Cool Daylight E14 8W 865) and a surface mounted light (Luxero T5LL-21 W) with a fluorescent tube (FSL 21W 865/0). The light for the control condition dim warm-white was operationalized by the lefthand floor lamps (Fig 2). This condition is equipped with another compact fluorescent lamp (Philips Tornado E14 12W 827). The movable arms of the floor lamps with the E14 sockets were fixed to the cabin interior in both conditions with the light cone aligned to the ceiling. The operationalization of the lighting conditions is discussed in 4.3 Limitations.
The cabins were equipped with a measuring device ALP-01 from Asensetek Lighting Passport. The illuminance and color temperature were measured horizontally on the work surface. Under the bright daylight (BL) experimental condition, an average of 517.0 lx / 5417 K was measured. This generated a condition with high illuminance and daylight color as well as a correspondingly high blue component (Fig 1). An average of 67.5 lx / 2628 K was measured under the dim warm-white (WL), control condition resulting in low illuminance and warm-white color temperature with a correspondingly high red component (Fig 2). On average, the computer monitor had a very small influence on the room lighting 14.6 lx and 6466 K.
2.3 Variables
In this study the ANT-Short was used [29]. Participants were instructed to react as quickly as possible to the direction of a middle arrow on a computer screen and click with the left or right thumb on the left or right mouse button.
The Conflict effect (Executive attention) is calculated by the difference in reaction times between trials with congruent arrows and incongruent arrows [30]. The stimuli are illustrated in Fig 3.
(a-h): congruent bottom (a-b), incongruent bottom (c-d), congruent top (e-f), incongruent top (g-h).
The Orienting effect is calculated by the difference in reaction times between trials with a center cue and spatial cue [30]. The stimuli are illustrated in Fig 4.
(a-d): no cue–only fixation cross (a), center cue (b), spatial cue bottom (c), spatial cue top (d).
The Alerting effect is calculated by the difference in reaction times between trials with no cue and a center cue [30]. The stimuli are also illustrated in Fig 4.
As light could also affect each conditions of the ANT in the same way, the conditions (congruent, incongruent, informative, center, no cue) were evaluated individually, even though this is not explicitly provided for in the ANT manual.
Based on the findings in the previous studies, ratings of acute stress were also obtained. The scale rest and restlessness of the multidimensional state questionnaire (MBDF) [36] was used. Self-formulated short scales were used to determine the following control variables: long-term stress, consumption of caffeine intake, chronotype, night sleep, nationality, mother tongue, glasses/contact lenses, left/right-handedness, and chronic diseases. In further details sunshine hours duration of the day [37], room temperature (temperature), date and time were recorded. Additionally, pulse and blood pressure were measured with blood pressure monitors (Sanitas SBC 15).
2.4 Procedure
The data collection took place from 20.04.2021 to 16.05.2021. The light condition was determined at random (coin toss). Accordingly, the luminaires were therefore fitted with the appropriate lamps for lighting condition, switched on and the room temperature measured. This procedure was determined in order to create comparable initial conditions and to allow the light effect to work. The adult participants were informed in both written and verbal form about the study and gave their written consent. The participants were first asked to complete questionnaires. This should result in a total acclimatization and exposure of about 10 minutes before the actual experiment. The experimenter stayed in the cabin during the instruction of the ANT and the test trial. Afterwards pulse and blood pressure were measured. Then the experimenter left the cabin and the participants completed the experiment, consisting of three ANT blocks each containing 48 trials. Each of these blocks was followed by a response on the scale of calm / restlessness. Pulse and blood pressure values were measured for the second time and afterwards the participant was send-off.
2.5 Ethics
The experiment was conducted in accordance with the Declaration of Helsinki and was approved by the Ethics Committee of Medical School Hamburg (MSH-2020105).
2.6 Statistics
An analysis of variance (ANOVA between subjects) was used. Using two-side testing and a local error probability of 5%, at least small effects were anticipated. A Huynh-Feldt correction was used when the sphericity assumption was violated. The dependent variables were successfully tested for normal distribution by testing kurtosis and skewness.
3. Results
3.1 Analysis of the ANT
Table 2 shows a significant effect of small size in the main variable of interest, executive function, in favor of the bright daylight group. This means that an average participant in the bright light group has a 11.3% shorter time difference between the congruence and no congruence conditions than an average participant in the control group with dimmed warm white light. The small effect for orienting (n.s.) and the absence of an effect for alerting are as expected. There are no effects in the individual conditions of the ANT, see Table 3.
3.2 Stress
Table 4 shows that there was no significant light effect (time*group) on the perceived stress of the participants during the test. In contrast, a significant effect of small size was found for the time course.
4. Discussion
4.1 Main results
The present study investigates whether higher performances observed in attentional functions under bright daylight than under dim warm light and whether stress perception is different between the light conditions. The anticipated impact on executive function in favor of the bright daylight condition, compared to the dimmed warm white light condition, can be confirmed. As anticipated, the orienting effect is smaller in this experiment, and no alerting effect is observed. No light effect was observed in relation to stress.
4.2 The relationship of the present results with previous studies and the pathways of the effect of light on human behavior
The result is consistent with the previous studies, although these were conducted in a school context with children and adolescents due to a lack of comparable studies on adults, and the light programs exhibited a much greater contrast, as outlined in the limitations. Since an effect of executive function could be demonstrated in the present study, and the previous studies with non-specific concentration tests also found effects [3, 4, 8], these can probably be explained by selective attention, i.e., an increase in executive function. An influence of light on orienting [31] and alerting [30] is also conceivable, although it is probably less possible to depict this in the present experiment with its short duration. Accordingly, the result here is also as expected.
Furthermore, the effect found in the computer-based ANT test suggests that the effect cannot be solely attributed to visual stimuli, either in the present study or in the previous studies.
Due to the established effect of light on executive functions, it can be inferred that the anterior cingulate cortex (ACC) in the human brain is activated [29]. Firstly, this would indicate a short-term biological activation, and secondly, the ACC is part of the limbic system like the SCN. This can thus be considered as an indication that the short-term effect of light occurs via similar biological mechanisms as the long-term effect of light, namely the synchronization of circadian rhythms.
The observations of Auras et al. [3] that daylight interventions subjectively lead to higher stress levels could not be confirmed in this study. No effect in the stress load was found. Presumably, the effect of light on the perception of stress depends on the state of arousal. Highly stressed people like the children in the psychiatric hospital in the study by Auras et al. [3] may first need a calming dimmed warm white light. However, the setting and the experimental population showed considerable differences between the present study and the reference study, so that further research on this question is necessary.
4.3 Limitations
In contrast to the previous studies, this study administered a computer-based test, whereas the reference studies are based on paper pencil tests [4, 8, 26]. In addition, the monitors emitted white light as screen background regardless of the lighting condition administered. So the contrast between the light conditions was not as pronounced as in the reference studies. In the warm white condition, the monitor acted as a confounding factor, reducing the contrast between the warm white and daylight white lighting. Consequently, the effects we observed are likely underestimated. In addition, the daylight condition in the reference studies by Barkmann et al. [4] and Slegers et al. [8] were approximately twice as intense with approximately 1000 Lux. In the study of Auras et al. [3], the daylight condition was also significantly brighter (793 lux) as was the case with Wessolowski [26], with almost 1300 lx. This could have resulted in possible effects of the light that could not be represented reliably.
Another limitation is that the lighting conditions were not generated from only one luminaire as in Barkmann et al. [4] and Slegers et al. [8] but from different luminaires. Thus, other lighting parameters varied except for illuminance and the most similar color temperature. However, the present study was carried out entirely without funding from the lighting industry and was financed entirely from the authors’ private funds. This is certainly not ideal for an experiment, but the change of the lighting situation by different favorable light sources corresponds to frequent practice in real life.
The data collection took place in spring and early summer. Although the test cabins were largely isolated from natural daylight, the participants were certainly influenced by natural daylight experienced previously outside the lab. It is conceivable that natural daylight outside the experiment was much more effective than artificial light in the experiment and caused strong undesired stimulation, especially in the control condition. For example, Kent et al. demonstrated a significant correlation between natural daylight exposure of the participants, as measured by NASA satellites, and their performance on cognitive tests [38]. Although an influence of sunshine duration (local weather data) on the test results could not be determined (not shown here), it seems conceivable that our results are conflated by previous exposure to bright daylight.
4.4 Summary
In terms of executive attention in the ANT test utilized, the results favored the daylight condition. Since the test was computerized for both the daylight and warm white light groups with constant monitor settings, the effect cannot be solely attributed to the visual impact of light. Although ambient light can also affect visibility on the monitors, this effect is likely to be very minor in the relatively short experiment. Light seems to directly affect executive attention and presumably selective attention, with activation observed in the anterior cingulate cortex (ACC) [39], a component of the circadian system. Van der Valle also demonstrates that short-term light interventions result in the activation of brain regions associated with the circadian system [23]. This suggests that the short-term impact of light on attentional performance may share a similar biological, non-visual pathway with the circadian effect of light. The parallel functioning of the psychological pathway cannot be completely ruled out and could be possible, for example, through a moderating relationship [21, 40, 41]. The visual pathway also cannot be entirely excluded due to potential indirect effects.
A non-significant effect of small magnitude was observed for orienting, and no effect was found for alerting, potentially attributable to the brief duration of the experiment.
In the present study, nor in the cognitive psychological theory [42] can it be clarified whether the effect of light on executive function is due to increased focus during task performance or to better recovery during the breaks between the ANT blocks. It is also possible that warm white light at low illuminance levels has a better effect than bright daylight during breaks, in line with the presented theory on the effect of light (effect pathways), while the opposite is true when working on the test tasks. A counter-indicative effect [43] due to disruptive light stimulation can likely be ruled out in this experiment, as the stress level in both groups was moderate and did not change. Both lighting programs were also rated similarly positively in terms of subjective liking (not shown here).
In principle, the experiment should be expanded on a larger scale and with more pronounced light contrasts. The lighting scenarios do not appear to influence subjects’ stress perception, at least not in this experiment; however, this could be attributed to sample size, experimental setting, and participants’ arousal levels.
This basic research study provides evidence that light influences attention not only visually. It also supports the practical effects of short-term daylight on attention enhancement in classrooms. The short-term use of artificial daylight in schools [3, 4, 26], universities [26], office workplaces, industrial facilities, and control rooms appears to be a sensible way to increase attention and concentration. Therapeutic use for attention disorders is also a possibility.
References
- 1.
Rea MS. Light—Much More Than Vision. 2002 [cited 1 Jan 2002]. Available: https://pdfs.semanticscholar.org/db8f/5ba0be450279bce83054781b513a70fc35ff.pdf
- 2. Weitbrecht WU, Bärwolff H, Lischke A, Jünger S. [Effect of Light Color Temperature on Human Concentration and Creativity]. Fortschr Neurol Psychiatr. 2015;83: 344–348. pmid:26098084
- 3. Auras MI, Barkmann C, Niemeyer M, Schulte-Markwort M, Wessolowski N. Wirksamkeit von variablem Licht in der Kinder- und Jugendpsychiatrie. Z Für Kinder- Jugendpsychiatrie Psychother. 2016;44: 148–157. pmid:27008904
- 4. Barkmann Claus. Applicability and efficacy of variable light in schools. Physiol Behav. 2012;105: 621–627. pmid:22001491
- 5. Boyce PR, Beckstead JW, Eklund NH, Strobel RW, Rea MS. Lighting the graveyard shift: The influence of a daylight-simulating skylight on the task performance and mood of night-shift workerst. Light Res Technol. 1997;29: 105–134.
- 6. Figueiro M, Rea MS, Boyce P, White R, Kolberg K. The effects of bright light on day and night shift nurses’ performance and well-being in the NICU. Neonatal Intensive Care. 2001;14: 29–32.
- 7.
Fleischer SE. Die psychologische Wirkung veränderlicher Kunstlichtsituationen auf den Menschen. Doctoral Thesis, ETH Zurich. 2001. https://doi.org/10.3929/ethz-a-004122647
- 8. Sleegers P, Moolenaar N, Galetzka M, Pruyn A, Sarroukh B, van der Zande B. Lighting affects students’ concentration positively: Findings from three Dutch studies. Light Res Technol. 2013;45: 159–175.
- 9. Wessolowski N, Koenig H, Schulte-Markwort M, Barkmann C. The effect of variable light on the fidgetiness and social behavior of pupils in school. J Environ Psychol. 2014;39: 101–108.
- 10. Brickenkamp R. Aufmerksamkeits-Belastungs-Test d2. 2002 [cited 26 Nov 2019]. Available: https://www.testzentrale.de/shop/test-d2-aufmerksamkeits-belastungs-test.html
- 11.
Pinel JPJ. Biopsychology. Needham Heights, MA: Allyn & Bacon; 1990.
- 12.
Goldstein EB. Sensation and perception, 4th ed. Belmont, CA: Thomson Brooks/Cole Publishing Co; 1996.
- 13. van Bommel W, van den Beld G. Lighting for work: a review of visual and biological effects. Light Res Technol. 2004;36: 255–266.
- 14. Berson DM, Dunn FA, Takao M. Phototransduction by retinal ganglion cells that set the circadian clock. Science. 2002;295: 1070–1073. pmid:11834835
- 15. Brainard GC, Hanifin JP, Greeson JM, Byrne B, Glickman G, Gerner E, et al. Action spectrum for melatonin regulation in humans: evidence for a novel circadian photoreceptor. J Neurosci. 2001;21: 6405–6412. pmid:11487664
- 16. Hattar S, Liao HW, Takao M, Berson DM, Yau KW. Melanopsin-containing retinal ganglion cells: architecture, projections, and intrinsic photosensitivity. Science. 2002;295: 1065–1070. pmid:11834834
- 17. Knez I. Effects of indoor lighting on mood and cognition. J Environ Psychol. 1995;15: 39–51.
- 18. Knez I, Enmarker I. Effects of office lighting on mood and cognitive performance and a gender effect in work-related judgment. Environ Behav. 1998;30: 553–567.
- 19. Baron RA, Rea MS, Daniels SG. Effects of indoor lighting (illuminance and spectral distribution) on the performance of cognitive tasks and interpersonal behaviors: The potential mediating role of positive affect. Motiv Emot. 1992;16: 1–33.
- 20. Biner PM, Butler DL, Fischer AR, Westergren AJ. An arousal optimization model of lighting level preferences: An interaction of social situation and task demands. Environ Behav. 1989;21: 3–16.
- 21. Cajochen C. Alerting effects of light. Sleep Med Rev. 2007;2007: 453–464. pmid:17936041
- 22. Smolders KCHJ, de Kort YAW. Bright light and mental fatigue: Effects on alertness, vitality, performance and physiological arousal. J Environ Psychol. 2014;39: 77–91.
- 23. Vandewalle G, Maquet P, Dijk D-J. Light as a modulator of cognitive brain function. Trends Cogn Sci. 2009;13: 429–438. pmid:19748817
- 24. Sahin L, Wood BM, Plitnick B, Figueiro MG. Daytime light exposure: Effects on biomarkers, measures of alertness, and performance. Behav Brain Res. 2014;274: 176–185. pmid:25131505
- 25. Okamoto Y, Rea MS, Figueiro MG. Temporal dynamics of EEG activity during short- and long-wavelength light exposures in the early morning. BMC Res Notes. 2014;7: 113. pmid:24568149
- 26.
Wessolowski N. Wirksamkeit von Dynamischem Licht im Schulunterricht. Dissertation, Universitätsklinikum Hamburg-Eppendorf. 2014. Available: ediss.sub.uni-hamburg.de/volltexte/2014/6759/pdf/Dissertation.pdf
- 27.
Hesse J, Schrader HC. Testtraining Konzentrationsvermögen. Frankfurt: Eichborn.exakt; 1999.
- 28.
Moosbrugger H, Kelava A. Testtheorie und Fragebogenkonstruktion. Berlin Heidelberg: Springer; 2012.
- 29. Fan J, McCandliss BD, Fossella J, Flombaum JI, Posner MI. The activation of attentional networks. NeuroImage. 2005;26: 471–479. pmid:15907304
- 30. Mu Y-M, Huang X-D, Zhu S, Hu Z-F, So K-F, Ren C-R, et al. Alerting effects of light in healthy individuals: a systematic review and meta-analysis. Neural Regen Res. 2022;17: 1929. pmid:35142669
- 31. Tonetti L, Natale V. Effects of a single short exposure to blue light on cognitive performance. Chronobiol Int. 2019;36: 725–732. pmid:30897969
- 32. Souman JL, Tinga AM, te Pas SF, van Ee R, Vlaskamp BNS. Acute alerting effects of light: A systematic literature review. Behav Brain Res. 2018;337: 228–239. pmid:28912014
- 33. Lok R, Smolders KCHJ, Beersma DGM, de Kort YAW. Light, Alertness, and Alerting Effects of White Light: A Literature Overview. J Biol Rhythms. 2018;33: 589–601. pmid:30191746
- 34.
Kaluza G. Stressbewältigung: Das Manual zur psychologischen Gesundheitsförderung. 5., vollst. überarb. Aufl. 2023 Edition. Berlin Heidelberg: Springer; 2023.
- 35. Faul F, Erdfelder E, Buchner A, Lang A-G. Statistical power analyses using G*Power 3.1: Tests for correlation and regression analyses. Behav Res Methods. 2009;41: 1149–1160. pmid:19897823
- 36.
Steyer R, Notz P, Schwenkmezger P, Eid M. MDBF—Der Mehrdimensionale Befindlichkeitsfragebogen. Göttingen: Hogrefe Verlag; 1997. Available: https://www.testzentrale.de/shop/der-mehrdimensionale-befindlichkeitsfragebogen.html
- 37.
Deutscher Wetterdienst. Wetter und Klima—Deutscher Wetterdienst—Thema des Tages—Sonnenbrand hinter Glas? 2022 [cited 1 Feb 2024]. Available: https://www.dwd.de/DE/wetter/thema_des_tages/2022/4/24.html
- 38. Kent ST, McClure LA, Crosson WL, Arnett DK, Wadley VG, Sathiakumar N. Effect of sunlight exposure on cognitive function among depressed and non-depressed participants: a REGARDS cross-sectional study. Environ Health. 2009;8: 34. pmid:19638195
- 39. Fan J, McCandliss BD, Sommer T, Raz A, Posner MI. Testing the Efficiency and Independence of Attentional Networks. J Cogn Neurosci. 2002;14: 340–347. pmid:11970796
- 40.
Beck S, Khanh TQ. Biosignale als Indikator der Lichtwirkungen auf Menschen–eine Literaturstudie der letzten Jahrzehnte. Lux junior. 2017.
- 41.
Wessolowski N. Licht, Farbe und Psyche: Theorie, Forschung und praktische Empfehlungen. 1st ed. epubli; 2024.
- 42. Schumann F, Steinborn MB, Kürten J, Cao L, Händel BF, Huestegge L. Restoration of Attention by Rest in a Multitasking World: Theory, Methodology, and Empirical Evidence. Front Psychol. 2022;13. pmid:35432083
- 43. Schmidt LM, Chaieb L, Derner M, Reber TP, Fell J. Side effects of monaural beat stimulation during sustained mental work on mind wandering and performance measures. Front Psychol. 2024;15. pmid:38708020