scholarly journals Nocturnal Melatonin Suppression by Adolescents and Adults for Different Levels, Spectra, and Durations of Light Exposure

2019 ◽  
Vol 34 (2) ◽  
pp. 178-194 ◽  
Author(s):  
Rohan Nagare ◽  
Mark S. Rea ◽  
Barbara Plitnick ◽  
Mariana G. Figueiro
Keyword(s):  
White Light ◽  
Exposure Duration ◽  
Light Exposure ◽  
Age Groups ◽  
Light Level ◽  
Light Spectra ◽  
Melatonin Suppression ◽  
Level Spectrum ◽  
Adolescents And Adults ◽  
Age Range

The human circadian system is primarily regulated by the 24-h LD cycle incident on the retina, and nocturnal melatonin suppression is a primary outcome measure for characterizing the biological clock’s response to those light exposures. A limited amount of data related to the combined effects of light level, spectrum, and exposure duration on nocturnal melatonin suppression has impeded the development of circadian-effective lighting recommendations and light-treatment methods. The study’s primary goal was to measure nocturnal melatonin suppression for a wide range of light levels (40 to 1000 lux), 2 white light spectra (2700 K and 6500 K), and an extended range of nighttime light exposure durations (0.5 to 3.0 h). The study’s second purpose was to examine whether differences existed between adolescents’ and adults’ circadian sensitivity to these lighting characteristics. The third purpose was to provide an estimate of the absolute threshold for the impact of light on acute melatonin suppression. Eighteen adolescents (age range, 13 to 18 years) and 23 adults (age range, 24 to 55 years) participated in the study. Results showed significant main effects of light level, spectrum, and exposure duration on melatonin suppression. Moreover, the data also showed that the relative suppressing effect of light on melatonin diminishes with increasing exposure duration for both age groups and both spectra. The present results do not corroborate our hypothesis that adolescents exhibit greater circadian sensitivity to short-wavelength radiation compared with adults. As for threshold, it takes longer to observe significant melatonin suppression at lower CS levels than at higher CS levels. Dose-response curves (amount and duration) for both white-light spectra and both age groups can guide lighting recommendations when considering circadian-effective light in applications such as offices, schools, residences, and healthcare facilities.

scholarly journals Effect of exposure duration and light spectra on nighttime melatonin suppression in adolescents and adults

2018 ◽  
Vol 51 (4) ◽  
pp. 530-543 ◽  
Author(s):  
R Nagare ◽  
B Plitnick ◽  
MG Figueiro
Keyword(s):  
Repeated Measures ◽  
Short Wavelength ◽  
Exposure Duration ◽  
Light Exposure ◽  
Circadian Phase ◽  
Light Spectra ◽  
Melatonin Suppression ◽  
Main Effect ◽  
Adolescents And Adults ◽  
Wavelength Radiation

This study investigated how light exposure duration affects melatonin suppression, a well-established marker of circadian phase, and whether adolescents (13–18 years) are more sensitive to short-wavelength (blue) light than adults (32–51 years). Twenty-four participants (12 adolescents, 12 adults) were exposed to three lighting conditions during successive 4-h study nights that were separated by at least one week. In addition to a dim light (<5 lux) control, participants were exposed to two light spectra (warm (2700 K) and cool (5600 K)) delivering a circadian stimulus of 0.25 at eye level. Repeated measures analysis of variance revealed a significant main effect of exposure duration, indicating that a longer duration exposure suppressed melatonin to a greater degree. The analysis further revealed a significant main effect of spectrum and a significant interaction between spectrum and participant age. For the adolescents, but not the adults, melatonin suppression was significantly greater after exposure to the 5600 K intervention (43%) compared to the 2700 K intervention (29%), suggesting an increased sensitivity to short-wavelength radiation. These results will be used to extend the model of human circadian phototransduction to incorporate factors such as exposure duration and participant age to better predict effective circadian stimulus.

scholarly journals Circadian Potency Spectrum with Extended Exposure to Polychromatic White LED Light under Workplace Conditions

2020 ◽  
Vol 35 (4) ◽  
pp. 405-415 ◽  
Author(s):  
Martin Moore-Ede ◽  
Anneke Heitmann ◽  
Rainer Guttkuhn
Keyword(s):  
Spectral Sensitivity ◽  
White Light ◽  
Light Exposure ◽  
Human Subjects ◽  
Light Sources ◽  
Led Light ◽  
Light Spectra ◽  
Timing System ◽  
Circadian Timing System ◽  
Spectral Sensitivity Curve

Electric light has enabled humans to conquer the night, but light exposure at night can disrupt the circadian timing system and is associated with a diverse range of health disorders. To provide adequate lighting for visual tasks without disrupting the human circadian timing system, a precise definition of circadian spectral sensitivity is required. Prior attempts to define the circadian spectral sensitivity curve have used short (≤90-min) monochromatic light exposures in dark-adapted human subjects or in vitro dark-adapted isolated retina or melanopsin. Several lines of evidence suggest that these dark-adapted circadian spectral sensitivity curves, in addition to 430- to 499-nm (blue) wavelength sensitivity, may include transient 400- to 429-nm (violet) and 500- to 560-nm (green) components mediated by cone- and rod-originated extrinsic inputs to intrinsically photosensitive retinal ganglion cells (ipRGCs), which decay over the first 2 h of extended light exposure. To test the hypothesis that the human circadian spectral sensitivity in light-adapted conditions may have a narrower, predominantly blue, sensitivity, we used 12-h continuous exposures of light-adapted healthy human subjects to 6 polychromatic white light-emitting diode (LED) light sources with diverse spectral power distributions at recommended workplace levels of illumination (540 lux) to determine their effect on the area under curve of the overnight (2000–0800 h) salivary melatonin. We derived a narrow steady-state human Circadian Potency spectral sensitivity curve with a peak at 477 nm and a full-width half-maximum of 438 to 493 nm. This light-adapted Circadian Potency spectral sensitivity permits the development of spectrally engineered LED light sources to minimize circadian disruption and address the health risks of light exposure at night in our 24/7 society, by alternating between daytime circadian stimulatory white light spectra and nocturnal circadian protective white light spectra.

scholarly journals Effect of White Light Devoid of “Cyan” Spectrum Radiation on Nighttime Melatonin Suppression Over a 1-h Exposure Duration

2019 ◽  
Vol 34 (2) ◽  
pp. 195-204 ◽  
Author(s):  
Rohan Nagare ◽  
Mark S. Rea ◽  
Barbara Plitnick ◽  
Mariana G. Figueiro
Keyword(s):  
Light Source ◽  
White Light ◽  
Exposure Duration ◽  
Ganglion Cells ◽  
Phase 1 ◽  
Biological Clock ◽  
Light Level ◽  
Light Signal ◽  
Light Sources ◽  
Experimental Conditions

The intrinsically photosensitive retinal ganglion cells are the main conduit of the light signal emanating from the retina to the biological clock located in the suprachiasmatic nuclei of the hypothalamus. Lighting manufacturers are developing white light sources that are devoid of wavelengths around 480 nm (“cyan gap”) to reduce their impact on the circadian system. The present study was designed to investigate whether exposure to a “cyan-gap,” 3000 K white light source, spectrally tuned to reduce radiant power between 475 and 495 nm (reducing stimulation of the melanopsin-containing photoreceptor), would suppress melatonin less than a conventional 3000 K light source. The study’s 2 phases employed a within-subjects experimental design involving the same 16 adult participants. In Phase 1, participants were exposed for 1 h to 3 experimental conditions over the course of 3 consecutive weeks: 1) dim light control (<5 lux at the eyes); 2) 800 lux at the eyes of a 3000 K light source; and 3) 800 lux at the eyes of a 3000 K, “cyan-gap” modified (3000 K mod) light source. The same protocol was repeated in Phase 2, but light levels were reduced to 400 lux at the eyes. As hypothesized, there were significant main effects of light level ( F1,12 = 9.1, p < 0.05, ηp² = 0.43) and exposure duration ( F1,12 = 47.7, p < 0.05, ηp² = 0.80) but there was no significant main effect of spectrum ( F1,12 = 0.16, p > 0.05, ηp² = 0.01). There were no significant interactions with spectrum. Contrary to our model predictions, our results showed that short-term exposures (≤ 1 h) to “cyan-gap” light sources suppressed melatonin similarly to conventional light sources of the same CCT and photopic illuminance at the eyes.

scholarly journals 0240 Nocturnal Melatonin Suppression In Adolescents And Adults For Different Levels, Spectra And Durations Of Light Exposure

SLEEP ◽  
2019 ◽  
Vol 42 (Supplement_1) ◽  
pp. A99-A99
Author(s):  
Rohan M Nagare ◽  
Mark S Rea ◽  
Barbara A Plitnick ◽  
Mariana G Figueiro
Keyword(s):  
Light Exposure ◽  
Melatonin Suppression ◽  
Adolescents And Adults ◽  
Different Levels

scholarly journals The Structure of Adolescent and Adult Savoring and  Its Relationship to Feeling Good and Functioning Well

2021 ◽  
Author(s):  
◽  
Erica D. Chadwick
Keyword(s):  
Positive Emotions ◽  
Age Groups ◽  
Developmental Differences ◽  
Positive Health ◽  
Positive Events ◽  
High Arousal ◽  
Negatively Associated ◽  
Adolescents And Adults ◽  
Broaden And Build Theory ◽  
Age Range

<p>I sought to contribute to the understanding of positive health, in particular savoring and wellbeing, by conducting concurrent and longitudinal studies with adolescents and adults. The thesis begins with a review of the literature including savoring theory (Bryant & Veroff, 2007) and the broaden-and-build theory of positive emotions (Fredrickson, 2001); these theories led to the key expectations that the psychometric structure of everyday savoring would be similar for adolescents and adults, and that amplifying savoring would positively predict wellbeing. Data obtained from two surveys, a paper-and-pencil survey with New Zealand adolescents (13 to 15 years old) and an internet-based survey with international adults (16 to 88 years old), were investigated in four studies across four empirical chapters (Chapters 2 through 5). Study 1 (Chapter 2) explored the similarities and differences in the psychometric structure of an abridged Ways of Savoring Checklist, labelled everyday savoring, between adolescents (N = 463) and adults (N = 980), as well as mean group differences in adolescents' and adults' degree of savoring. Study 2 (Chapter 3) investigated the concurrent relationships between adolescent and adult everyday savoring and hedonic and eudaimonic wellbeing as well as the ability of savoring to moderate wellbeing. Then, Study 3 and Study 4 investigated the relationships between savoring and wellbeing across time for adolescents (N = 265; Study 3, Chapter 4) and adults (N = 1858; Study 4, Chapter 5), including savoring as a mediator of the relationship between everyday positive events and wellbeing (Chapter 4), and orientations to happiness as a moderator of savoring and everyday positive events (Chapter 5). Results indicated that adolescents and adults yielded a similar four-factor structure of everyday savoring: dampening ("I don‘t deserve it"), low arousal ("I tried to slow down"), high arousal ("I jumped up and down"), and self-focus ("I reminded myself how lucky I was") savoring strategies, which proved to be invariant across time. The adolescent group, however, manifested a stronger association between amplifying (i.e. low arousal, high arousal, and self-focused savoring) and dampening savoring. Adolescents also reported higher levels of dampening compared to the adult group, whereas adults reported higher amplifying than adolescents. As expected, high arousal and self-focused savoring were positively, and dampening was negatively, associated with wellbeing indicators for adolescents and adults. However, low arousal savoring was negatively associated with hedonia for adolescents, but positively associated with eudaimonia for adults. The longitudinal analyses indicated that amplifying savoring predicted increases in wellbeing whereas dampening savoring predicted decreases in wellbeing for both age groups. The direction of effect, however, was not always as expected, questioning general assumptions of savoring theory and the broaden-and-build theory of positive emotions. These exceptions are most noted and explored in the final empirical chapter, Chapter 5. Overall the findings suggest that savoring is similar and similarly important for wellbeing over the age range incorporating adolescence to adulthood, although potential developmental differences are important to consider. The contribution of this thesis to the study of savoring, the field of positive psychology, and positive health development are reviewed in Chapter 6, as are the implications, limitations, and future directions.</p>

Synthetic and Natural Speech Preferences of Male and Female Listeners in Four Age Groups

1989 ◽  
Vol 32 (1) ◽  
pp. 175-183 ◽  
Author(s):  
Pat Mirenda ◽  
Douglas Eicher ◽  
David R. Beukelman
Keyword(s):  
Age Groups ◽  
Female Child ◽  
Synthetic Speech ◽  
Speech Technology ◽  
Male Adult ◽  
Adult Men ◽  
Communication Devices ◽  
Adolescents And Adults ◽  
And Gender ◽  
Age Range

The purpose of this investigation was to examine the preferences of listeners of both sexes in four age groups with regard to natural and computer-generated synthetic speech in six different contexts. The subjects (listeners) for this study included 5 males and 5 females in each of four age groups (6–8 year olds, 10–12 year olds, adolescents, and adults). The listeners rated their preferences for 11 different voices (four natural and seven synthetic) on a 5-point Likert scale. Their preferences were rated for six communication contexts dependent on the potential user of the voice (adult male, adult female, child male, child female, computer, and self). The data were analyzed separately for each of the six communication contexts. In general, female listeners across the age range indicated that only natural female voices (adult or child) were acceptable alternatives to their own speech, thus rejecting the natural male voices as well as the synthetic voices. Male listeners appeared to be somewhat more flexible in terms of gender-appropriateness for themselves and other adult men, but selected female-sounding voices for women and female children. Children preferred to have computers produce synthesized speech, while adults preferred computers with more natural-sounding voices. The results of this investigation raise a number of issues related to the combined effects of age and gender-appropriateness of natural and synthetic speech. These are discussed in terms of their implications for the future development of synthetic speech technology used in communication devices.

scholarly journals Development of functional corticomuscular connectivity from childhood to adulthood during precision grip with the dominant and non-dominant hand

2020 ◽  
Author(s):  
Mikkel Malling Beck ◽  
Meaghan Elizabeth Spedden ◽  
Jesper Lundbye-Jensen
Keyword(s):  
Motor Control ◽  
Precision Grip ◽  
Age Groups ◽  
Ontogenetic Development ◽  
List Type ◽  
Dominant Hand ◽  
Corticomuscular Coherence ◽  
Older Adolescents ◽  
Adolescents And Adults ◽  
Age Range

AbstractHow does the neural control of manual movements mature from childhood to adulthood? Here, we investigated developmental differences in functional corticomuscular connectivity using coherence techniques in 91 individuals recruited from four different age groups covering the age range 8-30y. EEG and EMG were recorded while participants performed a unimanual visual force-tracing task requiring fine control of the force produced in a precision grip with both the dominant and non-dominant hand. Using beamforming methods, we reconstructed source activity from EEG data displaying peak coherence with the active FDI muscle during the task in order to assess functional corticomuscular connectivity. Our results revealed that coherence was greater in adolescents and adults than in children and that the difference in coherence between children and adults was driven by a greater magnitude of descending (cortex-to-muscle) coherence. This was paralleled by the observation of a posterior-to-anterior shift in the cortical sources displaying corticomuscular coherence within the contralateral hemisphere from late adolescence. Finally, we observed that corticomuscular coherence was higher on the non-dominant compared to the dominant hand across age groups. These findings provide a detailed characterization of differences in task-related corticomuscular connectivity for individuals at different stages of typical ontogenetic development that may be related to the maturational refinement of dexterous motor control.Key points‐Fine motor control is gradually refined during human motor development, but little is known about the underlying neurophysiological mechanisms.‐Here, we used EEG and EMG to investigate functional corticomuscular connectivity during a precision grip with the dominant and non-dominant hand in 91 typically developed children, adolescents and adults (age range 8-30y).‐We show that older adolescents and adults are characterized by greater levels of corticomuscular coherence compared to children and that this is mainly driven by greater magnitudes of descending coherence (cortex-to-muscle). This is paralleled by a more anterior cortical site of coherence in older adolescents and adults compared to younger individuals.‐These results help us better understand the ontogenetic development of task-related functional connectivity in sensorimotor networks.

scholarly journals The Structure of Adolescent and Adult Savoring and  Its Relationship to Feeling Good and Functioning Well

2021 ◽  
Author(s):  
◽  
Erica D. Chadwick
Keyword(s):  
Positive Emotions ◽  
Age Groups ◽  
Developmental Differences ◽  
Positive Health ◽  
Positive Events ◽  
High Arousal ◽  
Negatively Associated ◽  
Adolescents And Adults ◽  
Broaden And Build Theory ◽  
Age Range

<p>I sought to contribute to the understanding of positive health, in particular savoring and wellbeing, by conducting concurrent and longitudinal studies with adolescents and adults. The thesis begins with a review of the literature including savoring theory (Bryant & Veroff, 2007) and the broaden-and-build theory of positive emotions (Fredrickson, 2001); these theories led to the key expectations that the psychometric structure of everyday savoring would be similar for adolescents and adults, and that amplifying savoring would positively predict wellbeing. Data obtained from two surveys, a paper-and-pencil survey with New Zealand adolescents (13 to 15 years old) and an internet-based survey with international adults (16 to 88 years old), were investigated in four studies across four empirical chapters (Chapters 2 through 5). Study 1 (Chapter 2) explored the similarities and differences in the psychometric structure of an abridged Ways of Savoring Checklist, labelled everyday savoring, between adolescents (N = 463) and adults (N = 980), as well as mean group differences in adolescents' and adults' degree of savoring. Study 2 (Chapter 3) investigated the concurrent relationships between adolescent and adult everyday savoring and hedonic and eudaimonic wellbeing as well as the ability of savoring to moderate wellbeing. Then, Study 3 and Study 4 investigated the relationships between savoring and wellbeing across time for adolescents (N = 265; Study 3, Chapter 4) and adults (N = 1858; Study 4, Chapter 5), including savoring as a mediator of the relationship between everyday positive events and wellbeing (Chapter 4), and orientations to happiness as a moderator of savoring and everyday positive events (Chapter 5). Results indicated that adolescents and adults yielded a similar four-factor structure of everyday savoring: dampening ("I don‘t deserve it"), low arousal ("I tried to slow down"), high arousal ("I jumped up and down"), and self-focus ("I reminded myself how lucky I was") savoring strategies, which proved to be invariant across time. The adolescent group, however, manifested a stronger association between amplifying (i.e. low arousal, high arousal, and self-focused savoring) and dampening savoring. Adolescents also reported higher levels of dampening compared to the adult group, whereas adults reported higher amplifying than adolescents. As expected, high arousal and self-focused savoring were positively, and dampening was negatively, associated with wellbeing indicators for adolescents and adults. However, low arousal savoring was negatively associated with hedonia for adolescents, but positively associated with eudaimonia for adults. The longitudinal analyses indicated that amplifying savoring predicted increases in wellbeing whereas dampening savoring predicted decreases in wellbeing for both age groups. The direction of effect, however, was not always as expected, questioning general assumptions of savoring theory and the broaden-and-build theory of positive emotions. These exceptions are most noted and explored in the final empirical chapter, Chapter 5. Overall the findings suggest that savoring is similar and similarly important for wellbeing over the age range incorporating adolescence to adulthood, although potential developmental differences are important to consider. The contribution of this thesis to the study of savoring, the field of positive psychology, and positive health development are reviewed in Chapter 6, as are the implications, limitations, and future directions.</p>

scholarly journals Exploring Why Adult Mexican Males Do Not Get Vaccinated: Implications for COVID-19 Preventive Actions

2020 ◽  
Vol 42 (4) ◽  
pp. 515-527
Author(s):  
V. Nelly Salgado de Snyder ◽  
Deliana Garcia ◽  
Roxana Pineda ◽  
Jessica Calderon ◽  
Dania Diaz ◽  
...  
Keyword(s):  
Preventive Medicine ◽  
Age Groups ◽  
Adult Males ◽  
Cross Sectional ◽  
Administrative Services ◽  
Minority Males ◽  
Socially Disadvantaged ◽  
Preventive Actions ◽  
Socially Excluded ◽  
Age Range

Vaccination is the single most important preventive medicine action worldwide. However, there are inequalities in the procurement of vaccines particularly among US ethnic and racial minority males when compared to the rest of the US population. This study explored the reasons given by adult Mexican-origin males residing in Texas, for obtaining or not, immunizations. This was a cross-sectional, exploratory study with a sample of convenience of 401 adult males (age range 18–79) who were invited to participate in the study while waiting their turn to receive administrative services at the Mexican Consulate in Austin Texas. Data was collected in Spanish with a seven-item multiple choice questionnaire, using electronic tablets. The majority of respondents received their last vaccination longer than 5 years earlier. A higher percentage of individuals in the older age groups received a vaccine in the last year, as opposed to their younger counterparts who obtained their last immunization 3 to 5 years earlier. Among the reasons given for not getting vaccinated were lack of time or money, feared injections and side effects, insufficient information, interest or motivation. Others did not get vaccines because they perceived themselves to be healthy and did not feel sick. Findings from this study have important implications for future preventive medicine and vaccination practices that reach socially excluded groups in times of COVID-19. Recommendations are made to facilitate access to vaccines to the target group of this study and other socially disadvantaged populations in the global health context.

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