scholarly journals Effects of an advanced sleep schedule and morning short wavelength light exposure on circadian phase in young adults with late sleep schedules

2011 ◽  
Vol 12 (7) ◽  
pp. 685-692 ◽  
Author(s):  
Katherine M. Sharkey ◽  
Mary A. Carskadon ◽  
Mariana G. Figueiro ◽  
Yong Zhu ◽  
Mark S. Rea
Keyword(s):  
Young Adults ◽  
Short Wavelength ◽  
Light Exposure ◽  
Circadian Phase ◽  
Sleep Schedule ◽  
Short Wavelength Light ◽  
Wavelength Light

scholarly journals Short-Wavelength Light Enhances Cortisol Awakening Response in Sleep-Restricted Adolescents

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Mariana G. Figueiro ◽  
Mark S. Rea
Keyword(s):  
Adrenal Gland ◽  
Short Wavelength ◽  
Light Exposure ◽  
Secondary Analysis ◽  
Cortisol Awakening Response ◽  
Dim Light ◽  
Short Wavelength Light ◽  
The Impact ◽  
Rising Time ◽  
Wavelength Light

Levels of cortisol, a hormone produced by the adrenal gland, follow a daily, 24-hour rhythm with concentrations reaching a minimum in the evening and a peak near rising time. In addition, cortisol levels exhibit a sharp peak in concentration within the first hour after waking; this is known as the cortisol awakening response (CAR). The present study is a secondary analysis of a larger study investigating the impact of short-wavelength(λmax≈470 nm)light on CAR in adolescents who were sleep restricted. The study ran over the course of three overnight sessions, at least one week apart. The experimental sessions differed in terms of the light exposure scenarios experienced during the evening prior to sleeping in the laboratory and during the morning after waking from a 4.5-hour sleep opportunity. Eighteen adolescents aged 12–17 years were exposed to dim light or to 40 lux (0.401 W/m2) of 470-nm peaking light for 80 minutes after awakening. Saliva samples were collected every 20 minutes to assess CAR. Exposure to short-wavelength light in the morning significantly enhanced CAR compared to dim light. Morning exposure to short-wavelength light may be a simple, yet practical way to better prepare adolescents for an active day.

scholarly journals No evidence for an S cone contribution to the human circadian response to light

2019 ◽  
Author(s):  
Manuel Spitschan ◽  
Rafael Lazar ◽  
Ebru Yetik ◽  
Christian Cajochen
Keyword(s):  
Retinal Ganglion Cells ◽  
Short Wavelength ◽  
Ganglion Cells ◽  
Light Exposure ◽  
Retinal Ganglion ◽  
Long Wavelength ◽  
Short Wavelength Light ◽  
The Brain ◽  
Wavelength Light

Exposure to even moderately bright, short-wavelength light in the evening can strongly suppress the production of melatonin and can delay our circadian rhythm. These effects are mediated by the retinohypothalamic pathway, connecting a subset of retinal ganglion cells to the circadian pacemaker in the suprachiasmatic nucleus (SCN) in the brain. These retinal ganglion cells directly express the photosensitive protein melanopsin, rendering them intrinsically photosensitive (ipRGCs). But ipRGCs also receive input from the classical photoreceptors — the cones and rods. Here, we examined whether the short-wavelength-sensitive (S) cones contribute to circadian photoreception by using lights which differed exclusively in the amount of S cone excitation by almost two orders of magnitude (ratio 1:83), but not in the excitation of long-wavelength-sensitive (L) and medium-wavelength-sensitive (M) cones, rods, and melanopsin. We find no evidence for a role of S cones in the acute alerting and melatonin supressing response to evening light exposure, pointing to an exclusive role of melanopsin in driving circadian responses.

scholarly journals Interventions to reduce short-wavelength (“blue”) light exposure at night and their effects on sleep: A systematic review and meta-analysis

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Ari Shechter ◽  
Kristal A Quispe ◽  
Jennifer S Mizhquiri Barbecho ◽  
Cody Slater ◽  
Louise Falzon
Keyword(s):  
Systematic Review ◽  
Effect Size ◽  
Short Wavelength ◽  
Total Sleep Time ◽  
Light Exposure ◽  
Meta Analysis ◽  
Sleep Time ◽  
Combined Effect ◽  
Short Wavelength Light ◽  
Wavelength Light

Abstract The sleep-wake and circadian cycles are influenced by light, particularly in the short-wavelength portion of the visible spectrum. Most personal light-emitting electronic devices are enriched in this so-called “blue” light. Exposure to these devices in the evening can disturb sleep. Interventions to reduce short-wavelength light exposure before bedtime may reduce adverse effects on sleep. We conducted a systematic review and meta-analysis to examine the effect of wearing color-tinted lenses (e.g. orange or amber) in frames to filter short-wavelength light exposure to the eye before nocturnal sleep. Outcomes were self-reported or objective measures of nocturnal sleep. Relatively few (k = 12) studies have been done. Study findings were inconsistent, with some showing benefit and others showing no effect of intervention. Meta-analyses yielded a small-to-medium magnitude combined effect size for sleep efficiency (Hedge’s g = 0.31; 95% CI: −0.05, 0.66; I2 = 38.16%; k = 7), and a small-to-medium combined effect size for total sleep time (Hedge’s g = 0.32; 95% CI: 0.01, 0.63; I2 = 12.07%; k = 6). For self-report measures, meta-analysis yielded a large magnitude combined effects size for Pittsburgh Sleep Quality Index ratings (Hedge’s g = −1.25; 95% CI: −2.39, −0.11; I2 = 36.35%; k = 3) and a medium combined effect size for total sleep time (Hedge’s g = 0.51; 95% CI: 0.18, 0.84; I2 = 0%; k = 3), Overall, there is some, albeit mixed, evidence that this approach can improve sleep, particularly in individuals with insomnia, bipolar disorder, delayed sleep phase syndrome, or attention-deficit hyperactive disorder. Considering the ubiquitousness of short-wavelength-enriched light sources, future controlled studies to examine the efficacy of this approach to improve sleep are warranted. Systematic review registration: PROSPERO 2018 CRD42018105854.

scholarly journals 0172 Blue-Light Blockers and Sleep: A Meta-Analysis of Intervention Studies

SLEEP ◽  
2020 ◽  
Vol 43 (Supplement_1) ◽  
pp. A68-A69
Author(s):  
A Shechter ◽  
K A Quispe ◽  
J S Mizhquiri Barbecho ◽  
L Falzon
Keyword(s):  
Short Wavelength ◽  
Light Exposure ◽  
Meta Analysis ◽  
Electronic Devices ◽  
Sleep Onset ◽  
Sleep Time ◽  
Combined Effect ◽  
Light Emitting ◽  
Short Wavelength Light ◽  
Wavelength Light

Abstract Introduction Sleep and circadian physiology are influenced by external light, particularly within the short-wavelength portion of the visible spectrum (~450–480 nm). Most personal light-emitting electronic devices (e.g., tablets, smartphones, computers) are enriched in this so-called “blue” light. Interventions to reduce short-wavelength light exposure to the eyes before bedtime may help mitigate adverse effects of light-emitting electronic devices on sleep. Methods We conducted a meta-analysis of intervention studies on the effects of wearing color-tinted lenses (e.g., orange or amber) in frames in the evening before sleep to selectively filter short-wavelength light exposure to the eyes. Outcomes were self-reported or objective (wrist-accelerometer) measures of nocturnal sleep. Databases (MEDLINE, EMBASE, Cochrane Library, PsycINFO, CINAHL, AMED) were searched from inception to November 2019. PROSPERO Registration: CRD42018105854. Results Ten studies were identified (7 randomized controlled trials; 3 before-after studies). Findings of individual studies were inconsistent, with some showing benefit and others showing no effect of intervention. For objective sleep onset latency, there was a significant modest-sized combined effect (Hedge’s g=-0.52, 95% CI: -1.27-0.24, Z=-2.94, p=0.003, I2=16.6%, k=3). There was a minor but non-statistically significant combined effect for objective sleep efficiency (Hedge’s g=0.24, 95% CI: -0.16–0.64, Z=1.69, p=0.09, I2=23.7%, k=5). There were no significant combined effects for objective measures of total sleep time and wake after sleep onset. For self-reported total sleep time, there was a statistically significant medium-sized combined effect (Hedge’s g=0.61, 95% CI: 0.14–1.09, Z=5.56, p<0.01, I2=0%, k=3). Conclusion There is mixed evidence that this approach can improve sleep. Relatively few studies have been conducted, and most did not assess light levels or melatonin. The “blue-blocker” intervention may be particularly useful in individuals with insomnia, delayed sleep phase syndrome, or attention-deficit hyperactive disorder. Considering the ubiquitousness of short wavelength-enriched light sources and the potential for widespread sleep disturbance, future controlled studies examining the efficacy of this approach to improve sleep are warranted. Support N/A

257 How Much Blue Do Blue-Blockers Block if Blue-Blockers Do Block Blue?

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A103-A103
Author(s):  
Brooke Mason ◽  
Andrew Tubbs ◽  
William Killgore ◽  
Fabian-Xosé Fernandez ◽  
Michael Grandner
Keyword(s):  
Light Source ◽  
Blue Light ◽  
Short Wavelength ◽  
Light Exposure ◽  
Visible Spectrum ◽  
Group Differences ◽  
Melatonin Secretion ◽  
Short Wavelength Light ◽  
Wavelength Light ◽  
One Way Anova

Abstract Introduction Short-wavelength light (440-530nm) can suppress endogenous melatonin secretion from the pineal gland. This has been observed in realworld settings when people use electronic media at night that emits light from this part of the visible spectrum. Blue-blocking glasses are a possible intervention to reduce blue light exposure. The present study evaluated the ability of commercially available blue-blockers to block blue light emitted by LEDs. Methods A calibrated spectroradiometer (Ocean Insight), cosine corrector, optic fiber, and software package were used to measure the absolute irradiance (uW/cm^2/nm) generated from a blue light source (Phillips Go Lite Blu) in an otherwise completely dark room. Thirty-one different commercially-available blue-blockers were individually placed between the cosine corrector and the light source at a standardized distance, and then intensity was measured and analyzed. Lenses were evaluated with regards to the amount of blue light they suppressed both individually and grouped by lens tint: red-tinted lenses (RTL), orange-tinted lenses (OTL), orange-tinted lenses with blue reflectivity (OBL), brown-tinted lenses (BTL), yellow-tinted lenses (YTL), and clear lenses with blue reflectivity (RBL). Results RTL blocked 100% of the short-wavelength light, while OTL and OBL blocked 99%, BTL blocked 66%, YTL blocked 38%, and RBL blocked 11% of it. This represented a statistically significant between-group difference (one-way ANOVA, < 0.0001). Within groups, there was variability in performance among individual lenses, though this variability was small compared to the between-group differences. Conclusion The RTL, OTL, and OBL block light best capable of suppressing melatonin secretion at night (440-530 nm); with slightly less efficacy, BTL and YTL also restricted much of the light exposure. Lastly, RBL were not effective at curtailing short-wavelength light. Those looking to optimize blue-blocking capabilities should use RTL, OTL, and OBL, rather than other lens types. Support (if any):

scholarly journals Fundamentals of circadian entrainment by light

2021 ◽  
Vol 53 (5) ◽  
pp. 377-393
Author(s):  
RG Foster
Keyword(s):  
Ganglion Cells ◽  
Light Exposure ◽  
Bright Light ◽  
Evidence Based ◽  
Retinal Ganglion ◽  
Rods And Cones ◽  
Long Duration ◽  
Lighting Systems ◽  
Short Wavelength Light ◽  
Wavelength Light

Light at dawn and dusk is the key signal for the entrainment of the circadian clock. Light at dusk delays the clock. Light at dawn advances the clock. The threshold for human entrainment requires relatively bright light for a long duration, but the precise irradiance/duration relationships for photoentrainment have yet to be fully defined. Photoentrainment is achieved by a network of photosensitive retinal ganglion cells (pRGCs) which utilise the short-wavelength light-sensitive photopigment, melanopsin. Although rods and cones are not required, they do play a role in photoentrainment, by projecting to and modulating the endogenous photosensitivity of the pRGCs, but in a manner that remains poorly understood. It is also important to emphasise that the age and prior light exposure of an individual will modify the efficacy of entrainment stimuli. Because of the complexity of photoreceptor interactions, attempts to develop evidence-based human centric lighting are not straightforward. We need to study how humans respond to dynamic light exposure in the ‘real world’ where light intensity, duration, spectral quality and the time of exposure vary greatly. Defining these parameters will allow the development of electric lighting systems that will enhance human circadian entrainment.

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