scholarly journals Alerting and Circadian Effects of Short-Wavelength vs. Long-Wavelength Narrow-Bandwidth Light during a Simulated Night Shift

2020 ◽  
Vol 2 (4) ◽  
pp. 502-522
Author(s):  
Erlend Sunde ◽  
Torhild Pedersen ◽  
Jelena Mrdalj ◽  
Eirunn Thun ◽  
Janne Grønli ◽  
...  
Keyword(s):  
Task Performance ◽  
Short Wavelength ◽  
Night Shift ◽  
Spectral Composition ◽  
Photon Density ◽  
Light Conditions ◽  
Long Wavelength ◽  
Narrow Bandwidth ◽  
Short Wavelength Light ◽  
Wavelength Light

Light can be used to facilitate alertness, task performance and circadian adaptation during night work. Novel strategies for illumination of workplaces, using ceiling mounted LED-luminaires, allow the use of a range of different light conditions, altering intensity and spectral composition. This study (ClinicalTrials.gov Identifier NCT03203538) investigated the effects of short-wavelength narrow-bandwidth light (λmax = 455 nm) compared to long-wavelength narrow-bandwidth light (λmax = 625 nm), with similar photon density (~2.8 × 1014 photons/cm2/s) across light conditions, during a simulated night shift (23:00–06:45 h) when conducting cognitive performance tasks. Light conditions were administered by ceiling mounted LED-luminaires. Using a within-subjects repeated measurements study design, a total of 34 healthy young adults (27 females and 7 males; mean age = 21.6 years, SD = 2.0 years) participated. The results revealed significantly reduced sleepiness and improved task performance during the night shift with short-wavelength light compared to long-wavelength light. There was also a larger shift of the melatonin rhythm (phase delay) after working a night shift in short-wavelength light compared to long-wavelength light. Participants’ visual comfort was rated as better in the short-wavelength light than the long-wavelength light. Ceiling mounted LED-luminaires may be feasible to use in real workplaces, as these have the potential to provide light conditions that are favorable for alertness and performance among night workers.

Turtle C-type horizontal cells act as push–pull devices

2001 ◽  
Vol 18 (6) ◽  
pp. 893-900 ◽  
Author(s):  
G. TWIG ◽  
H. LEVY ◽  
I. PERLMAN
Keyword(s):  
Short Wavelength ◽  
Horizontal Cells ◽  
Background Illumination ◽  
Voltage Range ◽  
Long Wavelength ◽  
Relative Contribution ◽  
Color Opponency ◽  
Light Stimuli ◽  
Short Wavelength Light ◽  
Wavelength Light

Chromaticity (C-type) horizontal cells in the retina of cold-blooded vertebrates receive antagonistic inputs from cone photoreceptors of different spectral types leading to color opponency. The relative contribution of each spectral type of cones can be selectively altered by chromatic background illumination. Therefore, the spectral properties of C-type horizontal cells are expected to change when the intensity and color of ambient illumination are altered. In this study, we investigated the effects of chromatic background lights upon color opponency in Red/Green (RGH) and Yellow/Blue (YBH) C-type horizontal cells in the everted eyecup preparation of the turtle Mauremys caspica. Photoresponses were elicited by long-wavelength and short-wavelength light stimuli in the dark-adapted state and under conditions of chromatic background illumination. We found that the total voltage range, within which graded depolarizing and the hyperpolarizing photoresponses could be elicited, either increased or decreased depending upon the color of the background light. However, the maximal and minimal potential levels determined respectively by long-wavelength and short-wavelength light stimuli of supersaturating intensity remained unchanged, regardless of the wavelength and intensity of the background. These findings indicate that turtle C-type horizontal cells operate as push–pull devices. A sufficiently bright short-wavelength stimulus can push them all the way to the maximal hyperpolarizing level while a very bright long-wavelength stimulus can pull them towards the most depolarizing potential.

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.

USE OF A SPECIALIZED MAGNETORECEPTION SYSTEM FOR HOMING BY THE EASTERN RED-SPOTTED NEWT NOTOPHTHALMUS VIRIDESCENS

1994 ◽  
Vol 188 (1) ◽  
pp. 275-291 ◽  
Author(s):  
J Phillips ◽  
S Borland
Keyword(s):  
Magnetic Field ◽  
Short Wavelength ◽  
Magnetic Compass ◽  
Compass Orientation ◽  
Full Spectrum ◽  
Long Wavelength ◽  
Magnetic Compass Orientation ◽  
Short Wavelength Light ◽  
The Magnetic Field ◽  
Wavelength Light

Laboratory experiments were carried out to investigate the effects of varying the wavelength of light on the use of an earth-strength magnetic field for shoreward orientation and for the compass component of homing. In the earlier shoreward orientation experiments, newts tested under full-spectrum and short-wavelength (i.e. 400 and 450 nm) light exhibited shoreward magnetic compass orientation. Under long-wavelength (i.e. 550 and 600 nm) light, newts exhibited magnetic compass orientation that was rotated 90 ° counterclockwise to the shoreward direction. This wavelength-dependent shift in magnetic compass orientation was shown to be due to a direct effect of light on the underlying magnetoreception mechanism. In homing experiments, newts tested under full-spectrum and short-wavelength light exhibited homeward magnetic compass orientation. Under long-wavelength light, newts were randomly distributed with respect to the magnetic field. The different effects of long-wavelength light on shoreward orientation and homing confirmed earlier evidence that different magnetoreception systems mediate these two forms of orientation behaviour. The properties of the newt's homing response are consistent with the use of a hybrid magnetoreception system receiving inputs from the light-dependent magnetic compass and from a non-light-dependent intensity (or inclination) detector which, unlike the compass, is sensitive to the polarity of the magnetic field.

scholarly journals Effect of long-wavelength light on electroencephalogram and subjective alertness

2020 ◽  
Vol 52 (6) ◽  
pp. 763-774
Author(s):  
J Lin ◽  
S Westland
Keyword(s):  
Short Wavelength ◽  
Circadian System ◽  
Long Wavelength ◽  
Self Rating ◽  
Beta Power ◽  
Short Wavelength Light ◽  
Subjective Alertness ◽  
Wavelength Light ◽  
Different Levels

This study extends previous findings on the effect of different levels of short-wavelength light on human alertness. This study explores the alerting ability of long-wavelength light at two levels (40 lx and 160 lx). Eight subjects took part in the 60-minute experiment for each of two nights, during which their objective alertness and subjective alertness were evaluated using electroencephalogram and questionnaire. Results show that both levels increased electroencephalogram beta power, which shows a different pattern compared with the previous findings on short-wavelength light. These results strongly suggest that although short-wavelength light may impact alertness through circadian system, long-wavelength light will have to achieve that through other pathways. The further comparison between current and previous results also suggests that long-wavelength light is just as strong on acute alerting ability, as shown by electroencephalogram measures and self-rating questionnaire, as short-wavelength light.

scholarly journals Restricting short-wavelength light in the evening to improve sleep in recreational athletes – A pilot study

2018 ◽  
Vol 19 (6) ◽  
pp. 728-735 ◽  
Author(s):  
Melanie Knufinke ◽  
Lennart Fittkau-Koch ◽  
Els I. S. Møst ◽  
Michiel A. J. Kompier ◽  
Arne Nieuwenhuys
Keyword(s):  
Pilot Study ◽  
Short Wavelength ◽  
Recreational Athletes ◽  
Short Wavelength Light ◽  
Wavelength Light
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