The effects of spectral tuning of evening ambient light on melatonin suppression, alertness and sleep

doi:10.1016/j.physbeh.2017.05.002

Physiology & Behavior

Volume 177, 1 August 2017, Pages 221-229

https://doi.org/10.1016/j.physbeh.2017.05.002 Get rights and content

Highlight

•
Pre-bedtime light exposure disrupts sleep and circadian rhythms.
•
We tested whether these disruptions are attenuated under dim blue-depleted light.
•
Blue-depleted ambient light reduced melatonin suppression and alertness.

Abstract

We compared the effects of bedroom-intensity light from a standard fluorescent and a blue- (i.e., short-wavelength) depleted LED source on melatonin suppression, alertness, and sleep. Sixteen healthy participants (8 females) completed a 4-day inpatient study. Participants were exposed to blue-depleted circadian-sensitive (C-LED) light and a standard fluorescent light (FL, 4100 K) of equal illuminance (50 lx) for 8 h prior to a fixed bedtime on two separate days in a within-subject, randomized, cross-over design. Each light exposure day was preceded by a dim light (< 3 lx) control at the same time 24 h earlier. Compared to the FL condition, control-adjusted melatonin suppression was significantly reduced. Although subjective sleepiness was not different between the two light conditions, auditory reaction times were significantly slower under C-LED conditions compared to FL 30 min prior to bedtime. EEG-based correlates of alertness corroborated the reduced alertness under C-LED conditions as shown by significantly increased EEG spectral power in the delta-theta (0.5–8.0 Hz) bands under C-LED as compared to FL exposure. There was no significant difference in total sleep time (TST), sleep efficiency (SE%), and slow-wave activity (SWA) between the two conditions. Unlike melatonin suppression and alertness, a significant order effect was observed on all three sleep variables, however. Individuals who received C-LED first and then FL had increased TST, SE% and SWA averaged across both nights compared to individuals who received FL first and then C-LED. These data show that the spectral characteristics of light can be fine-tuned to attenuate non-visual responses to light in humans.

Introduction

Light is a direct stimulant which increases brain activation and alertness [21] and impedes the ability to fall asleep and reduces sleep quality [6]. Evening light exposure suppresses the pineal hormone melatonin, the biochemical signal of darkness [31], [39]. Ordinary room light (i.e., 100 lx or less) can induce these effects [5], [12], [39]. These ‘non-visual’ effects of light are mediated primarily by the non-rod, non-cone melanopsin-containing photoreceptors located in intrinsically photosensitive retinal ganglion cells (ipRGCs) and are maximally sensitive to short-wavelength blue light (λ_max ~ 480 nm) [1], [4], [16], [17], [33]. We and others have shown that filtering out short-wavelength light from high intensity (> 1000 lx) broad-spectrum fluorescent white light can prevent melatonin suppression [14], [23], [24], [28], [29], [34], but whether this approach works under bedroom-light intensity [< 100 lx [2], [30]] is not known. The relative contribution of ipRGCs is less under dim lighting [13]; therefore, targeted reduction of short-wavelength light may be less effective under dim light conditions.

The effects of high CCT (blue-enriched lighting) and low CCT (blue-depleted) fluorescent lighting at bedroom-light intensity (40 lx) on melatonin suppression and alertness have been compared in one prior study [7]. The light sources used contained several peaks in the short-wavelength region (380–500 nm), even when blue-depleted [7], however. Using an LED source would enable more specific removal of these peaks in the short-wavelength region of the visible spectrum, which may further enhance the attenuation in melatonin suppression and other non-visual responses.

The effects of a custom-designed blue-depleted LED source on melatonin suppression, alertness and sleep has been compared in a comprehensive study with various different light sources varying in spectral composition and intensity [27], but light intensity for the blue-depleted condition (~ 240 lx) was higher than typical bedroom or pre-bedtime intensities [2], [30]. Therefore, in the current study, we compared the effects of bedroom-intensity (50 lx) light from a standard fluorescent and a blue-depleted LED source on melatonin suppression, alertness, and sleep. We hypothesized that an 8-h evening light exposure with short wavelengths selectively reduced (C-LED; a novel proprietary circadian photobiology-informed Light Emitting Diode) would cause less pre-sleep melatonin suppression than a commercially available fluorescent (FL) source. Moreover, we explored the effects of C-LED exposure on subjective and objective sleepiness prior to bedtime and nocturnal sleep.

Section snippets

Participants

Sixteen healthy participants [8 females; mean age (± SD): 24.2 ± 3.0 years] were studied in the Intensive Physiological Monitoring (IPM) Unit in the Center for Clinical Investigation at Brigham and Women's Hospital. The study was approved by the Partners Human Research Committee, and participants provided written informed consent. Clinical Trial Registration Number: NCT01586039. All had comprehensive but unremarkable physical, psychological and ophthalmologic exams, including a negative Ishihara

FM-100 chromatic discrimination

Binocular color discrimination was significantly worse under C-LED compared to FL [Farnsworth Munsell D-100 [11] median (± SD) score, FL: 42 ± 52.3; C-LED: 96 ± 57.5 units; p < 0.05 Mann-Whitney Test], although both median scores were within average range for color discrimination ability [11], [25].

Melatonin suppression

The mean melatonin profiles showed significant (p < 0.01) increase in melatonin levels with time under the dim-control, C-LED and FL condition. Levels were highest under dim light conditions followed by C-LED

Discussion

The results support our hypothesis that exposure to a 50-lx C-LED white light source spectrally tuned to reduce melanopic lux specifically will attenuate melatonin suppression between DLMO and bedtime compared to a 50-lx standard FL white light source. These results are consistent with previous studies from ours and other laboratories that have reduced melatonin suppression as well as disruption in other circadian phase markers by either entirely or almost entirely filtering short wavelengths

Funding

This work was supported by an investigator-initiated grant from Biological Illuminations LLC, a subsidiary of Lighting Science Group Corporation (LSGC), who also provided the study lights. SAR and MSH were supported in part by NIH/NHLBI T32-HL007901. The project described was supported by Grant Number 1 UL1 TR 001102 and Grant Number 8 UL1 TR000170-05, Harvard Clinical and Translational Science Center, from the National Center for Advancing Translational Sciences. The content is solely the

Competing interests

SAR holds a patent for Prevention of Circadian Rhythm Disruption by Using Optical Filters and Improving sleep performance in subject exposed to light at night; SAR owns equity in Melcort Inc., which owns a stake in Circadian ZircLight Inc., SAR is a co-investigator on studies sponsored by Biological Illuminations, LLC; Vanda Pharmaceuticals Inc. MSH has been a co-investigator on studies sponsored by Biological Illuminations, LLC and Philips HealthCare Solutions. SWL holds a consulting contract

Acknowledgements

We thank Alicia Foote, Wendy Chan, research staff, and research participants at the Division of Sleep and Circadian Disorders, Brigham and Women's Hospital (BWH); the technical, dietary, nursing and medical staff at the Center for Clinical Investigation at the BWH; Jonathan Williams M.D. for medical supervision; Core Laboratory staff (BWH) for melatonin assays; Robert Soler and Fred Maxik, Lighting Science Group Corporation for designing and providing the light sources.

References (39)

C. Cajochen et al.
Dose-response relationship for light intensity and ocular and electroencephalographic correlates of human alertness
Behav. Brain Res.
(2000)
D.J. Dijk et al.
Effect of a single 3-hour exposure to bright light on core body temperature and sleep in humans
Neurosci. Lett.
(1991)
R.J. Lucas et al.
Measuring and using light in the melanopsin age
Trends Neurosci.
(2014)
S. van der Lely et al.
Blue blocker glasses as a countermeasure for alerting effects of evening light-emitting diode screen exposure in male teenagers
J. Adolesc. Health
(2015)
G. Vandewalle et al.
Light as a modulator of cognitive brain function
Trends Cogn. Sci.
(2009)
K.P. Wright et al.
Entrainment of the human circadian clock to the natural light-dark cycle
Curr. Biol.
(2013)
G.C. Brainard et al.
Action spectrum for melatonin regulation in humans: evidence for a novel circadian photoreceptor
J. Neurosci.
(2001)
H.J. Burgess et al.
Home lighting before usual bedtime impacts circadian timing: a field study
Photochem. Photobiol.
(2014)
C. Cajochen et al.
Dynamics of EEG slow-wave activity and core body temperature in human sleep after exposure to bright light
Sleep
(1992)
C. Cajochen et al.
High sensitivity of human melatonin, alertness, thermoregulation, and heart rate to short wavelength light
J. Clin. Endocrinol. Metab.
(2005)

A.M. Chang et al.

Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness

Proc. Natl. Acad. Sci. U. S. A.

(2015)

S.L. Chellappa et al.

Non-visual effects of light on melatonin, alertness and cognitive performance: can blue-enriched light keep us alert?

PLoS One

(2011)

S.L. Chellappa et al.

Acute exposure to evening blue-enriched light impacts on human sleep

J. Sleep Res.

(2013)

S.L. Chellappa et al.

Human melatonin and alerting response to blue-enriched light depend on a polymorphism in the clock gene PER3

J. Clin. Endocrinol. Metab.

(2012)

D. Farnsworth

The Farnsworth Munsell 100 hue Test for the Examination of Colour Discrimination

(1957)

J.J. Gooley et al.

Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans

J. Clin. Endocrinol. Metab.

(2011)

J.J. Gooley et al.

Spectral responses of the human circadian system depend on the irradiance and duration of exposure to light

Sci. Transl. Med.

(2010)

L. Kayumov et al.

Blocking low-wavelength light prevents nocturnal melatonin suppression with no adverse effect on performance during simulated shift work

J. Clin. Endocrinol. Metab.

(2005)

P.R. Kinnear et al.

New Farnsworth-Munsell 100 hue test norms of normal observers for each year of age 5–22 and for age decades 30–70

Br. J. Ophthalmol.

(2002)

Cited by (93)

Visual and non-visual effects in micro-space luminous environments with visual display terminals
2024, Building and Environment
Working with visual display terminals (VDTs) is common in modern indoor spaces. It creates a distinct micro-space luminous environment, consisting of self-luminous screens and lighting backgrounds. However, integrative lighting, which considers both visual and non-visual effects of light, rarely focuses on such luminous environments. To address this gap, this study aims to explore the visual and non-visual effects in VDT luminous environments and how they are quantified at eye level. We conducted spectral simulations and laboratory experiments on various VDT lighting scenes and analyzed the illuminance and melanopic equivalent daylight illuminance (m-EDI) produced at eye level. Results show that the VDT luminous environment can be analyzed based on the light distribution of the vertical viewing plane where the VDT is located. Eye-level illuminance and m-EDI can vary by hundreds of lx depending on the screens and backgrounds in the VDT luminous environment. Despite the spatial distribution differences, both eye-level illuminance and m-EDI are linearly related to the averages of luminance and melanopic equivalent daylight luminance (m-EDL) of the VDT work plane, respectively. Additionally, the VDT screen has greater impacts on the eye-level illuminance and m-EDI compared to the lighting backgrounds that cover a larger area. The percentage of its contribution is exponentially related to the contrasts of the average screen-to-background luminance or m-EDL in the VDT luminous environment. These findings are expected to simplify and expedite the prediction of visual and non-visual effects and provide valuable insights for facilitating integrative lighting in VDT luminous environments.
The lower correlated color temperature with higher illuminance nocturnal light environment improves cognitive performance and sleep quality
2024, Building and Environment
Well-designed nocturnal light environment could boost performance on the cognitive tasks and promote sleep quality after light exposure. We optimized and fabricated a four-channel mixed white light with peak wavelengths of 429, 523, 591, and 621 nm. Comparing with common white light emitting diode (LED) (5798 K, 212.7 lx), the mixed white light has lower correlated color temperature (CCT) (2799 K), higher illuminance (356.2 lx), similar melanopic illuminance, and better color fidelity. We conducted experiments on 14 healthy young subjects (7 males and 7 females; age 18–25 years) to investigate the effects of nocturnal light environments on the cognitive performances and sleep quality. In consistent with the α-opic flux model, the mixed white light with higher illuminance shrinks the pupil size and has less melanopic flux, which results in more melatonin for subjects. More melatonin before sleep benefits the sleep quality by decreasing arousal times and improving sleep continuity. The higher illuminance light environment also promotes the inhibition ability and working memory. Moreover, it presents better color discrimination and less visual fatigue. Therefore, the lower CCT with higher illuminance nocturnal light environment effectively promotes both cognitive performances in the evening and the following sleep quality.
Ten questions concerning smart and healthy built environments for older adults
2023, Building and Environment
In the past decade, the term ‘global aging’ has gained much attention among researchers, policymakers, civil societies, and governments worldwide. The continuous decline in fertility rates and increased life expectancy have resulted in an ongoing demographic transition where the share of adults aged 65 or older is increasing and outnumbering children younger than five years. In the United States and other developed countries, this rapid demographic transition is expected to continue to strain the existing health infrastructure as it becomes increasingly challenging to ensure healthy living environments for older adults. The ten questions and answers in this paper have been prepared by experts from gerontology, geriatrics, architectural engineering, and senior living operations to inform and characterize the current continuum of living environments and communities available to older adults. They also identify the common elements that influence the environmental needs of older adults and highlight factors (such as technical assistance, health equity gaps, and caregiver workforce development) that challenge the future of smart and healthy built environments for older adults. A special focus has been placed on contextualizing indoor environmental quality (IEQ) elements and smart building technologies for older individuals, caregivers, and their various requirements (perhaps in their own homes and communities). Together, these viewpoints create a new paradigm to assist in designing and managing intelligent, healthy built environments that respond to human demands. Although this paper focuses on factors in the United States, others can benefit from the framework incubated upon these experiences, making this effort relevant toward addressing global opportunities in environments for older adults.
Integrated lighting ergonomics: A review on the association between non-visual effects of light and ergonomics in the enclosed cabins
2023, Building and Environment
The non-visual effects of light have become a hot topic in the study of how lighting environments affect humans. For an extended time, living and working in an isolated, confined, and enclosed (ICE) environment can have negative effects on the physiological and psychological issues of humans. In addition to the research on people's traditional visual ergonomics in the lighting environment, a new development trend is to pay attention to the ergonomics issue produced by non-visual (NV) effects, such as circadian rhythm, sleep, mental health, and performance, in the lighting environment. To protect the physical and mental well-being of individuals working in the enclosed cabins and to improve performance, it is vital to further develop new ergonomic research methodologies for the lighting environment. This paper reviewed relevant studies from the previous five years and follows the highly cited papers forward and backward to gain insight into the study and evaluation context of the non-visual effects of light. Based that, it is analyzed that the researches on sleep, alertness, and ergonomics in the enclosed cabins that induced by integrated lighting (IL, integrating the visual and non-visual effects of light). Reviewing research on the non-visual effects of light in the domains of medicine, ergonomics, and application, it is advised that integrated lighting ergonomics (ILE) research be conducted for crew living and working in the enclosed spaces, and that its objectives, methods, and design principles about ILE be described.
Near-infrared absorbing glazing for energy-efficient windows: A critical review and performance assessments from the building requirements
2023, Nano Energy
In the past decades, spectrally selective windows, such near-infrared absorbing (NIR) glazings, low-e glazings, and various smart windows, have been widely studied, developed, and applied in different climatic conditions for building energy-saving purposes. One major pathway of the spectrally selective glazings to achieve energy savings is through solar radiation control, either by NIR reflection or absorption. This review concerns the NIR absorbing glazings with the limited subset of ion-based and nanoparticle-based glazings. In detail, each category’s spectral absorbing materials are further distinguished into sub-categories, and then their underlying mechanisms of spectral selectivity were elaborated, as well as their application status in terms of manufacturing, cost, and commercialization popularity. To further advise the application in the building sector, we comparatively evaluated the performance of each kind of glazing in terms of the light and heat decoupling ability and visual qualities (i.e., color rendering). Finally, the challenges and future directions of the NIR absorbing glazings to bridge the gap between lab research and large-scale practical applications are illustrated.
Intrinsic imperfect and zero thermal quenching property for a novel β-NaYF<inf>4</inf>:Eu<sup>3+</sup>,Tb<sup>3+</sup> red-light emitting phosphor for NUV LEDs
2023, Journal of Alloys and Compounds
Despite long-term development of LEDs, problems urgent to resolve is still existing. The most outstanding problem to tackle is luminescent stability at high temperature working situation. In this study, a novel type of β-NaYF₄ based phosphor incorporated with Eu³⁺ and Tb³⁺ is reported. A series of β-NaYF₄:0.065Eu³⁺,xTb³⁺ (x = 0.001, 0.002, 0.003, 0.004, 0.005) phosphors were synthesized by hydrothermal method. The sample β-NaYF₄:0.065Eu³⁺,0.002Tb³⁺ possesses optimal luminescent property at room temperature. The mechanism of energy transfer from Tb³⁺ to Eu³⁺ ion is quadrupole-quadrupole interactions. The sample β-NaYF₄:0.065Eu³⁺,0.002Tb³⁺ demonstrates zero thermal quenching (ZTQ) property at 303 K to 383 K. According to XRD and XPS characterizations, nonequivalent replacement between intrinsic ion Na⁺ and Y³⁺ were discovered, which finally leads to production of crystal defects. According to electron paramagnetic resonance (EPR) characterization and density functional theory (DFT) calculation, the type of crystal defect of β-NaYF₄:0.065Eu³⁺,0.002Tb³⁺ is confirmed to be V_Y vacancies which are the predominant defect of crystal. The depths and densities of defects were calculated according to data of thermoluminescence spectra (TL spectra). Crystal defects play the role of electrons traps that could store electrons. Electrons stored in traps will be excited to excitation state of Eu³⁺ under the thermal stimulation to offset undesirable impact of thermal quenching (TQ), which leads to ZTQ property of the sample β-NaYF₄:0.065Eu³⁺,0.002Tb³⁺. The CRI and CCT of fabricated WLED are 3830 K and 84.1, respectively.

View all citing articles on Scopus

View full text

The effects of spectral tuning of evening ambient light on melatonin suppression, alertness and sleep

Highlight

Abstract

Introduction

Section snippets

Participants

FM-100 chromatic discrimination

Melatonin suppression

Discussion

Funding

Competing interests

Acknowledgements

Behav. Brain Res.

Neurosci. Lett.

Trends Neurosci.

J. Adolesc. Health

Trends Cogn. Sci.

Curr. Biol.

Action spectrum for melatonin regulation in humans: evidence for a novel circadian photoreceptor

J. Neurosci.

Home lighting before usual bedtime impacts circadian timing: a field study

Photochem. Photobiol.

Dynamics of EEG slow-wave activity and core body temperature in human sleep after exposure to bright light

Sleep

High sensitivity of human melatonin, alertness, thermoregulation, and heart rate to short wavelength light

J. Clin. Endocrinol. Metab.

Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness

Proc. Natl. Acad. Sci. U. S. A.

Non-visual effects of light on melatonin, alertness and cognitive performance: can blue-enriched light keep us alert?

PLoS One

Acute exposure to evening blue-enriched light impacts on human sleep

J. Sleep Res.

Human melatonin and alerting response to blue-enriched light depend on a polymorphism in the clock gene PER3

J. Clin. Endocrinol. Metab.

The Farnsworth Munsell 100 hue Test for the Examination of Colour Discrimination

Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans

J. Clin. Endocrinol. Metab.

Spectral responses of the human circadian system depend on the irradiance and duration of exposure to light

Sci. Transl. Med.

Blocking low-wavelength light prevents nocturnal melatonin suppression with no adverse effect on performance during simulated shift work

J. Clin. Endocrinol. Metab.

New Farnsworth-Munsell 100 hue test norms of normal observers for each year of age 5–22 and for age decades 30–70

Br. J. Ophthalmol.