Effects of blue pulsed light on human physiological functions and subjective evaluation

Background

It has been assumed that light with a higher irradiance of pulsed blue light has a much greater influence than that of light with a lower irradiance of steady blue light, although they have the same multiplication value of irradiance and duration. We examined the non-visual physiological effects of blue pulsed light, and determined whether it is sensed visually as being blue.

Findings

Seven young male volunteers participated in the study. We placed a circular screen (diameter 500 mm) in front of the participants and irradiated it using blue and/or white light-emitting diodes (LEDs), and we used halogen lamps as a standard illuminant. We applied three steady light conditions of white LED (F0), blue LED + white LED (F10), and blue LED (F100), and a blue pulsed light condition of a 100-μs pulse width with a 10% duty ratio (P10). The irradiance of all four conditions at the participant''s eye level was almost the same, at around 12 μW/cm². We measured their pupil diameter, recorded electroencephalogram readings and Kwansei Gakuin Sleepiness Scale score, and collected subjective evaluations. The subjective bluish score under the F100 condition was significantly higher than those under other conditions. Even under the P10 condition with a 10% duty ratio of blue pulsed light and the F10 condition, the participant did not perceive the light as bluish. Pupillary light response under the P10 pulsed light condition was significantly greater than under the F10 condition, even though the two conditions had equal blue light components.

Conclusions

The pupil constricted under the blue pulsed light condition, indicating a non-visual effect of the lighting, even though the participants did not perceive the light as bluish.     

Prolonged mild hypoxia modifies human circadian core body temperature and may be associated with sleep disturbances

Fatigue is often reported after long-haul airplane flights. Hypobaric hypoxia, observed in pressurized cabins, may play a role in this phenomenon by altering circadian rhythms. In a controlled cross-over study, we assessed the effects of two levels of hypoxia, corresponding to cabin altitudes of 8000 and 12,000 ft, on the rhythm of core body temperature (CBT), a marker of circadian rhythmicity, and on subjective sleep. Twenty healthy young male volunteers were exposed for 8 h (08:00-16:00 h) in a hypobaric chamber to a cabin altitude of 8000 ft and, 4 weeks later, 12,000 ft. Each subject served as his own control. For each exposure, CBT was recorded by telemetry for two 24 h cycles (control and hypoxic exposure). After filtering out nonphysiological values, the individual CBT data were fitted with a five-order moving average before statistical group analysis. Sleep latency, sleep time, and sleep efficiency were studied by sleep logs completed every day in the morning. Our results show that the CBT rhythm expression was altered, mainly at 12,000 ft, with a significant increase of amplitude and a delay in the evening decline in CBT, associated with alterations of sleep latency. Mild hypoxia may therefore alter circadian structure and result in sleep disturbances. These results may explain in part the frequent complaints of prolonged post-flight fatigue after long flights, even when no time zones are crossed.     

A taurine and caffeine-containing drink stimulates cognitive performance and well-being

Summary. Caffeine- and taurine-containing drinks have been on the European market for about a decade, and research on the individual constituents of these drinks indicates an improvement in cognitive performance resulting from consumption of such drinks. In this double-blind, placebo-controlled study using 10 graduate students, we obtained the P300 components of event-related potential (ERP) waveforms following an auditory oddball paradigm, measured motor reaction time, and applied the d2 test for the assessment of attention. Status of mood was assessed by the “Basler-Befindlichkeitsbogen” questionnaire, a standard test for evaluation of feelings of well-being. Measurements were made at night, prior to and starting one hour after consumption of energy drink ingredients or placebo. At the end of the experiment (midnight), P300 latency and motor reaction time were significantly longer compared with baseline measurements in the placebo group, but were unchanged in the energy drink group. In the test system for evaluating feelings of well-being, total scores, vitality scores and social extrovertedness scores were significantly decreased in the placebo group but not in the energy drink group. The findings clearly indicate that the mixture of three key ingredients of Red Bull^R Energy Drink used in the study (caffeine, taurine, glucuronolactone) have positive effects upon human mental performance and mood. These effects may be mediated by the action of caffeine on purinergic (adenosinergic) receptors and taurine modulation of receptors. As half of the study cohort were non-caffeine users, the described effects cannot be explained in terms of the restoration of plasma caffeine levels to normal following caffeine withdrawal. Received January 5, 2000/Accepted June 5, 2000     

Migrants,health, and happiness: Evidence that health assessments travel with migrants and predict well-being

Health assessments correlate with health outcomes and subjective well-being. Immigrants offer an opportunity to study persistent social influences on health where the social conditions are not endogenous to individual outcomes. This approach provides a clear direction of causality from social conditions to health, and in a second stage to well-being. Natives and immigrants from across the world residing in 30 European countries are studied using survey data. The paper applies within country analysis using both linear regressions and two stage least squares. Natives’ and immigrants’ individual characteristics have similar predictive power for health, except Muslim immigrants who experience a sizeable health penalty. Average health reports in the immigrant's birth country have a significant association with the immigrant's current health. Almost a quarter of the birth country health variation is brought by the immigrants, while conditioning on socioeconomic characteristics. There is no evidence of the birth country predictive power declining neither as the immigrant spends more time in the residence country nor over the life course. The second stage estimates indicate that a one standard deviation improvement in health predicts higher happiness by 1.72 point or 0.82 of a standard deviation, more than four times the happiness difference of changing employment status from unemployed to employed. Studying life satisfaction yields similar results. Health improvements predict substantial increases in individual happiness.     

Flexible Working Hours,Health, and Well-Being in Europe: Some Considerations from a SALTSA Project

The project brought together researchers from 9 EU-Countries and resulted in a number of actions, in particular the following: (a) There is an urgent need of defining the concept of flexible working hours, since it has been used in many different and even counterintuitive ways; the most obvious distinction is where the influence over the working hours lies, that is between the “company-based flexibility” and the “individual-oriented flexibility”; (b) The review of the Legislation in force in the 15 European countries shows that the regulation of working times is quite extensive and covers (Council Directive 93/104/EC) almost all the various arrangements of working hours (i.e., part-time, overtime, shift, and night work), but fails to provide for flexibility; (c) According to the data of the Third EU Survey on Working Conditions, longer and “irregular” working hours are in general linked to lower levels of health and well-being; moreover, low (individual) flexibility and high variability of working hours (i.e., company-based flexibility) were consistently associated with poor health and well-being, while low variability combined with high autonomy showed positive effects; (d) Six substudies from different countries demonstrated that flexible working hours vary according to country, economic sector, social status, and gender; overtime is the most frequent form of company-based flexibility but has negative effects on stress, sleep, and social and mental health; individual flexibility alleviates the negative effects of the company-based flexibility on subjective health, safety, and social well-being; (e) The literature review was able to list more than 1,000 references, but it was striking that most of these documents were mainly argumentative with very little empirical data. Thus, one may conclude that there is a large-scale intervention ongoing in our society with almost completely unknown and uncontrolled effects. Consequently, there is a strong need for systematic research and well-controlled actions in order to examine in detail what flexible working hours are considered, what and where are their positive effects, in particular, as concerns autonomy, and what regulation seem most reasonable.     

A new class of composite indicators for measuring well-being at the local level: An application to the Equitable and Sustainable Well-being (BES) of the Italian Provinces

The aim of this paper is to propose a class of composite indicators for measuring well-being at the local level, which takes into account the variability between and within the local units.Although we believe that well-being is a multidimensional concept and cannot be reduced to a single measure, we also stress the importance of aggregating the information of several well-being indicators into a reduced number of composite indicators, one for each well-being domain, which play a crucial role in policymaking and benchmarking.As an application, we focus on the Equitable andSustainable Well-being of the Italian Provinces. In particular, based on a dataset containing 41 elementary indicators, we aggregate them by domain, comparing different aggregative approaches and illustrating the difference in the rankings of the Italian Provinces they produce. Finally, as an illustrative example, we focus on a member of the class of composite indicators that accounts both for vertical variability (between the Provinces) and horizontal variability (within the Provinces). The construction of a composite index for each domain allows us to evaluate and compare multidimensional well-being among the Italian Provinces.     

Desarrollo y validación de un instrumento observacional para la evaluación del bienestar en personas con demencia desde la perspectiva de la atención centrada en la persona: Listado de Indicadores de Bienestar

IntroductionWithin the context of Person Centred Care, the present paper shows the creation and validation process of an observational tool for the assessment of the wellbeing of people with dementia, from a perspective that seeks to highlight the effects that the physical and social environment have on the person, and how these are reflected in the well-being.MethodsThe List of Wellbeing Indicators (LIBE) was created following an inductive iterative process with professionals from different disciplines, until the validated version was reached. It was then validated in two successive studies with a sample of 79 people with dementia. Discrimination capacity of the scale indicators, internal consistency, inter-rater reliability, and convergent and divergent validity were determined.ResultsAn internal consistency of Cronbach́s alpha 0.81 was obtained. The inter-rater reliability, analysing intraclass correlation coefficient (ICC) within the 3 raters, was significant for all the indicators in the tool, with scores between 0.59-1.00. Convergent validity was studied comparing scores in each LIBE indicator with scores in each QUALID indicator, and some significant associations were found between response categories in both tools. For the discriminant validity, the scores obtained in each LIBE indicator were compared with the scores in each PAINAD-Sp item, and no significant associations were found.ConclusionLIBE offers an observational measure of behaviours that can be considered well-being indicators in people with dementia living in residential care. LIBE is a valid and reliable tool that offers a different perspective of measuring a construct that has been infrequently explored in dementia population. Is also an easy to apply tool, with different uses (clinical, intervention, research), and applicable for professionals of several disciplines.     

The effects of progesterone pretreatment on the response to oral d-amphetamine in Women

Stimulant abuse continues to be a problem, particularly for women. There is increasing preclinical and clinical evidence showing that the hormone progesterone attenuates the behavioral effects of cocaine, and this effect is primarily observed in females. The purpose of the present study was to determine if progesterone would also alter the behavioral effects of another stimulant, oral d-amphetamine (AMPH) in women. Eighteen normal non-drug abusing women completed eight outpatient sessions over two menstrual cycles. During the follicular phase of each cycle, women were administered AMPH (0, 10, 20 mg); in one cycle they were pretreated with oral micronized progesterone (200 mg) and in another cycle they were pretreated with placebo progesterone. Each session, participants completed a range of tasks including subjective measures of abuse liability, cognitive performance tasks, and behavioral measures of impulsivity and risk-taking. AMPH produced dose-related increases in positive subjective effects and these effects were enhanced by progesterone pretreatment. AMPH alone, or in combination with progesterone, had little effect on performance or behavioral measures of impulsivity. These results are in contrast with previous studies showing that progesterone attenuates the subjective response to cocaine and nicotine. Additional studies are needed to explore the modulatory role of progesterone on the effects of AMPH to determine whether progesterone has any clinical utility for AMPH abuse.     

Does the response to cocaine differ as a function of sex or hormonal status in human and non-human primates?

Stimulant abuse continues to be a growing problem among women. Over the last 10-15 years, an increasing number of studies have focused on factors that may be implicated in stimulant abuse in women as compared to men, including the role of hormonal fluctuations across the menstrual cycle. Numerous preclinical studies have documented that female rodents are more sensitive than male rodents to the behavioral effects of stimulant administration and the hormone estradiol is involved in the enhanced response to stimulants observed in females. In contrast, fewer studies have been conducted in humans and non-human primates addressing the role of sex and gonadal hormones on the effects of cocaine. This review paper presents a recent update on data collected in our Human Cocaine Challenge Laboratory and our Non-human Primate Laboratory, including analysis of cocaine pharmacokinetics, sex differences, the menstrual cycle, and the role of progesterone in modulating the response to cocaine. Our studies indicate that there is minimal evidence that the response to intranasal cocaine varies across the menstrual cycle or between men and women. In contrast, the response to smoked cocaine is greater in the follicular phase than the luteal phase and differences between men and women generally only emerge when men are compared to women in the luteal phase. In terms of potential hormonal mechanisms for these differences, the hormone progesterone attenuates the subjective response to cocaine. With respect to cocaine self-administration, there are minimal changes across the menstrual cycle in both humans and non-human primates. Thus, there is converging evidence across a range of species that the behavioral effects of cocaine (1) differ between males and females, (2) differ in relation to hormonal fluctuations, (3) can be attenuated by progesterone (at least in females), and (4) do not appear to be related to differences in cocaine pharmacokinetics.     

Circadian Components in Energy and Tension and Their Relation to Physiological Activation and Performance

The purpose of the study was to examine validity of R. Thayer's activation model regarding 24 h variations of two subjective dimensions of activation (Energy and Tension), and their 24 h relations with indices of physiological activation and performance efficiency. The participants of the study (n = 28 females) spent 26 h under controlled laboratory conditions. Self-ratings of subjective activation and measurements of oral temperature, electrodermal activity, and performance on a visual vigilance task were done every 4 h. Twenty-four-hour variations were examined by means of repeated measures analyses of variance and by group mean cosinor analyses before and after controlling for the data trends. Self-ratings on both dimensions of subjective activation showed significant 24 h variation. Energy showed both nonrhythmic and endogenously determined circadian variation, while 24 h variation of tension was dominantly nonrhythmic and most probably determined by exogenous factors. Significant 24 h covariation was found between energy and body temperature. A negative correlation between 24 h variation of energy and tension was also found. Considering low and intermediate levels of subjective activation established over the 24 h in this study, the association of the two dimensions of subjective activation did not prove to be consistent with the assumptions of Thayer's model.