Bright light exposure of a large skin area does not affect melatonin or bilirubin levels in humans

Lindblom, Niki; Hätönen, Taina; Laakso, Minna; Alila-Johansson, Aino; Laipio, Marja-Leena; Turpeinen, Ursula

doi:10.1016/s0006-3223(00)00905-7

Cited by 22 publications

(10 citation statements)

References 31 publications

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“…In this study, no melatonin suppression through extraocular light was reported either to the popliteal zone or to the eyelids. In accordance with these results, Rogers et al (1999), Lindblom et al (2000a), and Wright and Czeisler (2002) failed to induce melatonin suppression by giving extraocular light. Only one additional effect of extraocular light has been reported.…”

supporting

confidence: 56%

Acute and Phase-Shifting Effects of Ocular and Extraocular Light in Human Circadian Physiology

et al. 2003

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Light can influence physiology and performance of humans in two distinct ways. It can acutely change the level of physiological and behavioral parameters, and it can induce a phase shift in the circadian oscillators underlying variations in these levels. Until recently, both effects were thought to require retinal light perception. This view was challenged by Campbell and Murphy, who showed significant phase shifts in core body temperature and melatonin using an extraocular stimulus. Their study employed popliteal skin illumination and exclusively considered phase-shifting effects. In this paper, the authors explore both acute effects and phase-shifting effects of ocular as well as extraocular light. Twelve healthy males participated in a within-subject design and received all of three light conditions--(1) dim ocular light/no light to the knee, (2) dim ocular light/bright extraocular light to the knee, and (3) bright ocular light/no light to the knee--on separate nights in random order. The protocol consisted of an adaptation night followed by a 26-h period of sustained wakefulness, during which a 4-h light pulse was presented at a time when maximal phase delays were expected. The authors found neither immediate nor phase-shifting effects of extraocular light exposure on melatonin, core body temperature (CBT), or sleepiness. Ocular bright-light exposure reduced the nocturnal circadian drop in CBT, suppressed melatonin, and reduced sleepiness significantly. In addition, the 4-h ocular light pulse delayed the CBT rhythm by -55 min compared to the drift of the CBT rhythm in dim light. The melatonin rhythm shifted by -113 min, which differed significantly from the drift in the melatonin rhythm in the dim-light condition (-26 min). The failure to find immediate or phase-shifting effects in response to extraocular light in a within-subjects design in which effects of ocular bright light are confirmed strengthens the doubts raised by other labs of the impact of extraocular light on the human circadian system.

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supporting

confidence: 56%

Acute and Phase-Shifting Effects of Ocular and Extraocular Light in Human Circadian Physiology

et al. 2003

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“…The most recent of these was by researchers from Cornell University, who suggested that bright light applied to the area behind the human knee would shift circadian rhythms of body temperature and melatonin (Campbell and Murphy 1998). But like earlier reports, these studies have not withstood independent verification (Koorengevel et al 2001;Lindblom et al 2000aLindblom et al , 2000bLockley et al 1998), suggesting that the original observations resulted from some unrecognised artefact of the experimental procedures (Foster 1998;Yamazaki et al 1999).…”

Section: Light Circadian Rhythms and Novel Ocular Photoreceptorsmentioning

confidence: 96%

Opsins and mammalian photoentrainment

Bellingham

Foster

2002

Cell Tissue Res

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Research over the past decade has provided overwhelming evidence that photoreception in the vertebrate eye is not confined to the rod and cone photoreceptors. It appears that photoreceptor cells within the inner retina provide irradiance information to a wide variety of different photosensory tasks including photoentrainment, pupillary constriction and masking behaviour. Action spectra in mice lacking all rod and cone photoreceptors ( rd/rd cl) have demonstrated the existence of a previously uncharacterised, opsin/vitamin-A-based photopigment with peak sensitivity at 479 nm (opsin photopigment/OP(479)). The review addresses the question: has the gene encoding OP(479) already been isolated, and if not, what type of gene should we be seeking and where in the eye might this gene be expressed? On the basis of available data, the gene that encodes OP(479) remains unidentified, and two broad possibilities exist. On the assumption that OP(479) will be like all of the other vertebrate photopigments (ocular and extraocular) and share a close phylogenetic relationship based upon amino acid identity and a conserved genomic structure, then the gene encoding OP(479) has yet to be isolated. Alternatively, there may have been a separate line of photopigment evolution in the vertebrates that has given rise to the melanopsin family. If true then the mammalian melanopsin gene may encode OP(479). Only when melanopsin and other candidates for OP(479) have been functionally expressed, and shown to encode a photopigment that matches the action spectrum of OP(479), can firm conclusions about the identity of the non-rod, non-cone ocular photoreceptor of mammals be made.

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“…Nonetheless, some scientists challenged the findings at the time for pragmatic reasons; namely, that eye loss in humans blocks photoentrainment [ 188 ]. Other groups attempted to replicate these findings using various approaches [ 189 , 190 , 191 ] and then the methodologies were replicated precisely [ 192 ]. All failed to show that light applied to the popliteal region would phase shift the circadian system.…”

Section: The Effects Of Light On the Human Circadian Systemmentioning

confidence: 99%

Circadian Photoentrainment in Mice and Humans

Foster

Hughes

Peirson

2020

Biology

109

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Light around twilight provides the primary entrainment signal for circadian rhythms. Here we review the mechanisms and responses of the mouse and human circadian systems to light. Both utilize a network of photosensitive retinal ganglion cells (pRGCs) expressing the photopigment melanopsin (OPN4). In both species action spectra and functional expression of OPN4 in vitro show that melanopsin has a λmax close to 480 nm. Anatomical findings demonstrate that there are multiple pRGC sub-types, with some evidence in mice, but little in humans, regarding their roles in regulating physiology and behavior. Studies in mice, non-human primates and humans, show that rods and cones project to and can modulate the light responses of pRGCs. Such an integration of signals enables the rods to detect dim light, the cones to detect higher light intensities and the integration of intermittent light exposure, whilst melanopsin measures bright light over extended periods of time. Although photoreceptor mechanisms are similar, sensitivity thresholds differ markedly between mice and humans. Mice can entrain to light at approximately 1 lux for a few minutes, whilst humans require light at high irradiance (>100’s lux) and of a long duration (>30 min). The basis for this difference remains unclear. As our retinal light exposure is highly dynamic, and because photoreceptor interactions are complex and difficult to model, attempts to develop evidence-based lighting to enhance human circadian entrainment are very challenging. A way forward will be to define human circadian responses to artificial and natural light in the “real world” where light intensity, duration, spectral quality, time of day, light history and age can each be assessed.

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Bright light exposure of a large skin area does not affect melatonin or bilirubin levels in humans

Cited by 22 publications

References 31 publications

Acute and Phase-Shifting Effects of Ocular and Extraocular Light in Human Circadian Physiology

Acute and Phase-Shifting Effects of Ocular and Extraocular Light in Human Circadian Physiology

Opsins and mammalian photoentrainment

Circadian Photoentrainment in Mice and Humans

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