Human responses to bright light of different durations

Chang, Anne Marie; Santhi, Nayantara; Hilaire, Melissa A St; Gronfier, Claude; Bradstreet, Dayna S.; Duffy, Jeanne F.; Lockley, Steven W.; Kronauer, Richard E.; Czeisler, Charles A.

doi:10.1113/jphysiol.2011.226555

Cited by 247 publications

(225 citation statements)

References 41 publications

Supporting

Mentioning

201

Contrasting

Unclassified

Order By: Relevance

“…We could have, as many laboratories do, used an antimuscarinic agent to dilate the pupils to avoid the pupillary light reflex and keep it from interfering with the amount of light striking the retina. Given the potential effect of antimuscarinics on the physiologic properties of retinal ganglion cells (74), we feel that the use of such agents would have created greater uncertainty in the interpretation of our results.A final consideration is that the phase shift observed in our study under continuous light was smaller than that observed in previous studies (41,49). This difference, however, is likely due to protocol dissimilarities in the intensity of the light exposure (49) and light history of the participants that could lead to a different sensitization of the photoreceptive system (41).…”

contrasting

confidence: 51%

“…of NIF photoreception in humans remains incompletely understood, as it has wavelength (35)(36)(37)(38)(39), intensity (40), duration (41), and pattern (42)(43)(44) responses that are considerably distinct from the traditional perceptual image-forming responses, and most knowledge in this field has been imputed from studies of nonhuman mammals. Understanding NIF characteristics and responses to light is crucial for the development and optimization of light therapy strategies.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Temporal integration of light flashes by the human circadian system

Najjar¹,

Zeitzer²

2016

Journal of Clinical Investigation

View full text Add to dashboard Cite

BACKGROUND.Beyond image formation, the light that is detected by retinal photoreceptors influences subcortical functions, including circadian timing, sleep, and arousal. The physiology of nonimage-forming (NIF) photoresponses in humans is not well understood; therefore, the development of therapeutic interventions based on this physiology, such as bright light therapy to treat chronobiological disorders, remains challenging. METHODS.Thirty-nine participants were exposed to 60 minutes of either continuous light (n = 8) or sequences of 2-millisecond light flashes (n = 31) with different interstimulus intervals (ISIs; ranging from 2.5 to 240 seconds). Melatonin phase shift and suppression, along with changes in alertness and sleepiness, were assessed. RESULTS.We determined that the human circadian system integrates flash sequences in a nonlinear fashion with a linear rise to a peak response (ISI = 7.6 ± 0.53 seconds) and a power function decrease following the peak of responsivity. At peak ISI, flashes were at least 2-fold more effective in phase delaying the circadian system as compared with exposure to equiluminous continuous light 3,800 times the duration. Flashes did not change melatonin concentrations or alertness in an ISI-dependent manner. CONCLUSION.We have demonstrated that intermittent light is more effective than continuous light at eliciting circadian changes. These findings cast light on the phenomenology of photic integration and suggest a dichotomous retinohypothalamic network leading to circadian phase shifting and other NIF photoresponses. Further clinical trials are required to judge the practicality of light flash protocols. light in a nonlinear fashion. Intermittent patterns of light tested thus far fail, however, to elicit greater changes in outcomes when compared with continuous light exposures. Shorter duration of light exposures in the order of microseconds to milliseconds have been tested in rodents (45)(46)(47). While a single 2-millisecond flash of light is insufficient to phase shift the murine circadian system, a sequence of flashes administered once per minute for 60 minutes is sufficient to evoke phase delays (48). This study by Van Den Pol and colleagues, in addition to other published studies in rodents (45)(46)(47), established that the mammalian circadian system has the capacity to respond to a sequence of very brief, millisecond flashes of light.of NIF photoreception in humans remains incompletely understood, as it has wavelength (35-39), intensity (40), duration (41), and pattern (42-44) responses that are considerably distinct from the traditional perceptual image-forming responses, and most knowledge in this field has been imputed from studies of nonhuman mammals. Understanding NIF characteristics and responses to light is crucial for the development and optimization of light therapy strategies. NIF responses to light in humans have mainly been tested using continuous or intermittent light exposures, ranging from the order of minutes up to more than 6 hours of bright light (41...

show abstract

contrasting

confidence: 51%

Section: Introductionmentioning

confidence: 99%

Temporal integration of light flashes by the human circadian system

Najjar¹,

Zeitzer²

2016

Journal of Clinical Investigation

View full text Add to dashboard Cite

show abstract

“…The current study confirms the results of the controlled lab studies [16,35] and supports the conclusion that a combination of short light pulses of 30 min. in the morning and dim light in the evening is also capable of advancing the melatonin rhythm when applied in a home situation with no real control over environmental light.…”

Section: Discussionsupporting

confidence: 81%

“…The 1h light pulses in the study of St. Hilaire et al [16] in humans elicited a maximal phase advance of 1.2h, which is 44% of the response of 2.7h generated by the 6.7h light exposure in the study of Khalsa et al [13]. Such dimin.ishing responses to extended stimulation are considered the result of adaptation processes; therefore the beginning of a light pulse is most important for the phase shifting effects [17].…”

Section: Introductionmentioning

confidence: 99%

Short Blue Light Pulses (30 Min.) in the Morning are Able to Phase Advance the Rhythm of Melatonin in a Home Setting

Geerdink¹,

Beersma²

2016

J Sleep Disord Ther

View full text Add to dashboard Cite

It is known that light in the morning is able to induce phase advances of the endogenous clock, however most studies have tested the phase advances in highly controlled laboratory conditions. At home the environmental lighting is more variable. In theory, a high intensity short morning-light pulse in the short-wavelengths-range (blue light) should be capable of inducing phase advances. If this is also true in a home setting, this could be a firm basis supporting light treatment in late chronotypes who suffer from a late sleep phase. In a study carried out in summer, 11 normal to relatively late (habitual midsleep 4:15-6:09 hours) chronotypes (age range 23-27 years, 4f/7m) participated in two conditions: (1) 1 baseline day followed by 3 consecutive days of 30 min. blue morning-light pulses, (2) 1 baseline day followed by 3 consecutive days of 60 min. blue light pulses. Blue light was applied by use of the Philips GoLite BLU (HF3320, blue leds, intensity at the cornea 2306 melanopic-lux, 300 lux, 3.65 W/m 2 ). During all four evenings, subjects were asked to protect themselves from light exposure (<10 lux). The response of the melatonin rhythm, calculated as a shift in dim light melatonin onset (DLMO), to a single 30 min. light pulse varied between subjects and resulted in a non-significant phase advance of 15 (±48) min. (t10 = 1.04; P = 0.33), and a significant advance of 30 (±41) min. to a single 60 min. light pulse. (t10 = 2.40; P < 0.05). After 3 days of light exposure both in the 30-and in the 60 min. light pulses condition significant phase advances of DLMO were observed; 49 (±58) min. (t10 = 2.80; P < 0.05) and 59 (±29) min. (t10 = 6.9; P < 0.001) respectively. No significant differences were found in the DLMO shifts between conditions. In addition there was a trend for a lower sleepiness score directly after waking up after using light for 3 days in both conditions (t10 = 3.38; P = 0.096, 60 min. and (t10 = 4.10; P = 0.070, 30 min.). A prelimin.ary analysis of actimetry data indicated some support for an effect on sleep timin.g. The data support the conclusion that light pulses of 30 min. in the morning on three consecutive days, in a home setting, in combination with dim light during the evenings, can be part of an efficient phase advancing chronotherapy protocol.

show abstract

“…Changing the sleep-wake cycle and ALAN resulted in phase advance of the MLT rhythm, which also reduced the circadian amplitude of the hormone in healthy men [222]. MLT suppression by ALAN has a dose-dependent response to both irradiance level and duration of the exposure [223]. Furthermore, the phase advance and suppression in MLT rhythms are intimately wavelength-dependent with more manifested effect at short wavelengths compared with long wavelengths [44,45,224].…”

Section: Circadian Disruption Biomarkers In Obesity and Cancer Researchmentioning

confidence: 92%

Artificial light-at-night – a novel lifestyle risk factor for metabolic disorder and cancer morbidity

Zubidat

Haim

2017

Journal of Basic and Clinical Physiology and Pharmacology

View full text Add to dashboard Cite

Both obesity and breast cancer are already recognized worldwide as the most common syndromes in our modern society. Currently, there is accumulating evidence from epidemiological and experimental studies suggesting that these syndromes are closely associated with circadian disruption. It has been suggested that melatonin (MLT) and the circadian clock genes both play an important role in the development of these syndromes. However, we still poorly understand the molecular mechanism underlying the association between circadian disruption and the modern health syndromes. One promising candidate is epigenetic modifications of various genes, including clock genes, circadian-related genes, oncogenes, and metabolic genes. DNA methylation is the most prominent epigenetic signaling tool for gene expression regulation induced by environmental exposures, such as artificial light-at-night (ALAN). In this review, we first provide an overview on the molecular feedback loops that generate the circadian regulation and how circadian disruption by ALAN can impose adverse impacts on public health, particularly metabolic disorders and breast cancer development. We then focus on the relation between ALAN-induced circadian disruption and both global DNA methylation and specific loci methylation in relation to obesity and breast cancer morbidities. DNA hypo-methylation and DNA hyper-methylation, are suggested as the most studied epigenetic tools for the activation and silencing of genes that regulate metabolic and monostatic responses. Finally, we discuss the potential clinical and therapeutic roles of MLT suppression and DNA methylation patterns as novel biomarkers for the early detection of metabolic disorders and breast cancer development.

show abstract

Human responses to bright light of different durations

Cited by 247 publications

References 41 publications

Temporal integration of light flashes by the human circadian system

Temporal integration of light flashes by the human circadian system

Short Blue Light Pulses (30 Min.) in the Morning are Able to Phase Advance the Rhythm of Melatonin in a Home Setting

Artificial light-at-night – a novel lifestyle risk factor for metabolic disorder and cancer morbidity

Contact Info

Product

Resources

About