Can short-wavelength depleted bright light during single simulated night shifts prevent circadian phase shifts?

Regente, Johannes; Zeeuw, Jan de; Bes, Frédérik; Nowozin, Claudia; Appelhoff, Stefan; Wahnschaffe, Amely; Münch, Mirjam; Kunz, Dieter

doi:10.1016/j.apergo.2016.12.014

Cited by 13 publications

(8 citation statements)

References 54 publications

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“…The wake-promoting effects of evening BL are well known, being reflected also in longer sleep latencies [52] and the impact on slow wave sleep, even when the exposure is of relatively low illuminance [53,54]. We recently showed that moderately bright OL during a simulated night shift had no detrimental effects on the following daytime sleep episode when compared to DL (there was a trend for more N3 sleep), confirming that longer-wavelength lighting in the evening/night does not delay or negatively impact on sleep [55]. Regarding the possible effects on sleep from morning light exposure, there was slightly longer N2 sleep after the MBL condition.…”

Section: Discussionmentioning

confidence: 59%

Blue-Enriched Morning Light as a Countermeasure to Light at the Wrong Time: Effects on Cognition, Sleepiness, Sleep, and Circadian Phase

Münch

Nowozin²,

Regente³

et al. 2016

Neuropsychobiology

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Light during the day and darkness at night are crucial factors for proper entrainment of the human circadian system to the solar 24-h day. However, modern life and work styles have led to much more time spent indoors, often with lower daytime and higher evening/nighttime light intensity from electrical lighting than outdoors. Whether this has long-term consequences for human health is being currently investigated. We tested if bright blue-enriched morning light over several days could counteract the detrimental effects of inadequate daytime and evening lighting. In a seminaturalistic, within-between subject study design, 18 young participants were exposed to different lighting conditions on 3 evenings (blue-enriched, bright orange, or dim light), after exposure to 2 lighting conditions (mixed blue-enriched light and control light, for 3 days each) in the mornings. Subjective sleepiness, reaction times, salivary melatonin concentrations, and nighttime sleep were assessed. Exposure to the blue-enriched morning lighting showed acute wake-promoting effects and faster reaction times than with control lighting. Some of these effects persisted until the evening, and performance improved over several days. The magnitude of circadian phase shifts induced by combinations of 3 different evening and 2 morning lighting conditions were significantly smaller with the blue-enriched morning light. During the night, participants had longer total sleep times after orange light exposure than after blue light exposure in the evening. Our results indicate that bright blue-enriched morning light stabilizes circadian phase, and it could be an effective counterstrategy for poor lighting during the day and also light exposure at the wrong time, such as in the late evening.

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Section: Discussionmentioning

confidence: 59%

Blue-Enriched Morning Light as a Countermeasure to Light at the Wrong Time: Effects on Cognition, Sleepiness, Sleep, and Circadian Phase

Münch

Nowozin²,

Regente³

et al. 2016

Neuropsychobiology

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“…62 When using an even longer wavelength, a red saturated red light peaking at 627 nm to 630 nm also showed little influence on melatonin suppression. 63 Later simulated studies have tried more realistic scenarios and demonstrated that also ceiling mounted LED-luminaires using fullnight, short-wavelength, narrow-bandwidth light could reduce sleepiness and improve task performance during the night-shift, compared to long-wavelength light and also phase delay the circadian rhythm. 64,65 And it seems that either blue or red light promote better performance compared to a dim light option.…”

Section: Rapidly Rotating Night Work To Slow Partial Night Adaptationmentioning

confidence: 99%

Considerations on how to light the night-shift

Löwden

Kecklund

2021

Lighting Research & Technology

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Electric lighting has decreased dependence on natural light to illuminate the workplace. Humans are genetically predisposed to be day-oriented (diurnal) and depend on daylight to regulate circadian rhythms. Shift work will force workers to sleep and work at non-biological times, inducing circadian disruption with implications for workers’ safety and health. The scientific literature may be used in practice in shift work settings to improve safety, performance and health in the workplace by reducing circadian misalignment. Alertness profiles at work and degree of melatonin suppression may indicate degree of circadian disruption among workers. However, when considering lighting solutions at night, there are several factors that need consideration. Light measures based on biological effectiveness should be used rather than room illuminance giving better predictions of performance and long-term health among workers. Also, large individual differences in light sensitivity and preferences suggest not only to rely on common lighting alone but also to implement complementary individual lighting solutions at work. Lighting advice should consider shift scheduling characteristics such as speed of turnover and shift timing to guide decisions of preferred circadian phase influence. Lighting should also include the flexibility to be fit for morning, afternoon and evening work.

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“…One of the most used proxies to assess acute responses to light is alertness, which is regulated by the integration of circadian, sleep-dependent, and other aspects (for a review, see Cajochen, 2007). A great portion of the alerting effects by light during the evening/night has been found concomitant with light-induced melatonin suppression (Cajochen et al, 2011; Cajochen et al, 2000; Chellappa et al, 2011; Lockley et al, 2006), even though some studies found that light at night can also increase alertness or cognitive performance without affecting the melatonin profile (Rahman et al, 2011; Regente et al, 2017). During the day, when people are usually synchronized to the light-dark cycle and melatonin is not secreted, the possible alerting effects of light are less clear.…”

Section: Introductionmentioning

confidence: 99%

Living in Biological Darkness: Objective Sleepiness and the Pupillary Light Responses Are Affected by Different Metameric Lighting Conditions during Daytime

et al. 2019

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Nighttime melatonin suppression is the most commonly used method to indirectly quantify acute nonvisual light effects. Since light is the principal zeitgeber in humans, there is a need to assess its strength during daytime as well. This is especially important since humans evolved under natural daylight but now often spend their time indoors under artificial light, resulting in a different quality and quantity of light. We tested whether the pupillary light response (PLR) could be used as a marker for nonvisual light effects during daytime. We also recorded the wake electroencephalogram to objectively determine changes in daytime sleepiness between different illuminance levels and/or spectral compositions of light. In total, 72 participants visited the laboratory 4 times for 3-h light exposures. All participants underwent a dim-light condition and either 3 metameric daytime light exposures with different spectral compositions of polychromatic white light (100 photopic lux, peak wavelengths at 435 nm or 480 nm, enriched with longer wavelengths of light) or 3 different illuminances (200, 600, and 1200 photopic lux) with 1 metameric lighting condition (peak wavelength at 435 nm or 480 nm; 24 participants each). The results show that the PLR was sensitive to both spectral differences between metameric lighting conditions and different illuminances in a dose-responsive manner, depending on melanopic irradiance. Objective sleepiness was significantly reduced, depending on melanopic irradiance, at low illuminance (100 lux) and showed fewer differences at higher illuminance. Since many people are exposed to such low illuminance for most of their day—living in biological darkness—our results imply that optimizing the light spectrum could be important to improve daytime alertness. Our results suggest the PLR as a noninvasive physiological marker for ambient light exposure effects during daytime. These findings may be applied to assess light-dependent zeitgeber strength and evaluate lighting improvements at workplaces, schools, hospitals, and homes.

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Can short-wavelength depleted bright light during single simulated night shifts prevent circadian phase shifts?

Cited by 13 publications

References 54 publications

Blue-Enriched Morning Light as a Countermeasure to Light at the Wrong Time: Effects on Cognition, Sleepiness, Sleep, and Circadian Phase

Blue-Enriched Morning Light as a Countermeasure to Light at the Wrong Time: Effects on Cognition, Sleepiness, Sleep, and Circadian Phase

Considerations on how to light the night-shift

Living in Biological Darkness: Objective Sleepiness and the Pupillary Light Responses Are Affected by Different Metameric Lighting Conditions during Daytime

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