Blocking Low-Wavelength Light Prevents Nocturnal Melatonin Suppression with No Adverse Effect on Performance during Simulated Shift Work

Abstract

Decreases in melatonin production in human and animals are known to be caused by environmental lighting, especially short-wavelength lighting (between 470 and 525 nm). We investigated the novel hypothesis that the use of goggles with selective exclusion of all wavelengths less than 530 nm could prevent the suppression of melatonin in bright-light conditions during a simulated shift-work experiment. Salivary melatonin levels were measured under dim (<5 lux), bright (800 lux), and filtered (800 lux) light at hourly intervals between 2000 and 0800 h in 11 healthy young males and eight females (mean age, 24.7 +/- 4.6 yr). The measurements were performed during three nonconsecutive nights over a 2-wk period. Subjective sleepiness was measured by self-report scales, whereas objective performance was assessed with the Continuous Performance Test. All subjects demonstrated preserved melatonin levels in filtered light similar to their dim-light secretion profile. Unfiltered bright light drastically suppressed melatonin production. Normalization of endogenous melatonin production while wearing goggles did not impair measures of performance, subjective sleepiness, or alertness.

Spectral modulation attenuates molecular, endocrine, and neurobehavioral disruption induced by nocturnal light exposure

“…Recent studies have demonstrated that filtering all wavelengths Ͻ530 nm attenuated nocturnal light-induced suppression of melatonin secretion (28,52). Furthermore, we have demonstrated in rats that filtering a narrow, 10-nm bandwidth of wavelengths between 470 and 480 nm from polychromatic white light prevents melatonin suppression, corticosterone elevation, and central and peripheral clock gene expression alterations induced by 12-h nocturnal light exposure following 12-h daytime light exposure (46).…”

“…However, physiological responses to different wavelengths of light may also be dependent on their relative intensities. Light with high correlated color temperature (short-wavelength/blue-enriched light) was more effective in suppressing melatonin at 200 lux intensity compared with light with low correlated color temperature (red-enriched light) (33), whereas at much higher intensities (4,000 -5,000 lux), differences between blue-enriched and regular white light on melatonin suppression have not been demonstrated (57,59).Recent studies have demonstrated that filtering all wavelengths Ͻ530 nm attenuated nocturnal light-induced suppression of melatonin secretion (28,52). Furthermore, we have demonstrated in rats that filtering a narrow, 10-nm bandwidth of wavelengths between 470 and 480 nm from polychromatic white light prevents melatonin suppression, corticosterone elevation, and central and peripheral clock gene expression alterations induced by 12-h nocturnal light exposure following 12-h daytime light exposure (46).…”

The Relationship between a Night Usage of Mobile Phone and Sleep Habit and the Circadian Typology of Japanese Students Aged 18 - 30 yrs

“…Over-use of the smart phone especially on bed at night may, not only, make Japanese students evening-typed, but also make sleep hours shorter and mental health worse. Exposure to short-wave light including lights with wavelengths of 460 nm at night seems to make their circadian clock phase delayed and also to suppress melatonin synthesis (Hashimoto et al, 1996;Zeitzer et al, 2000;Wright & Lack, 2001;Harada, 2004;Kayumov et al, 2005;Yasukouchi et al, 2007;Wada et al, 2013;Higuchi et al, 2014). Also long time exposure to lights from the display might affect central nervous system in human through other routes rather than affecting the circadian system.…”

Regulating Artificial Light at Night: A Comparison Between the South Korean and English Approaches

“…Now that the broad problems justifying the regulation of artificial light at night have been set out, we may now consider the possible mechanisms for legal control 13 . These mechanisms must be able to address these key problems, whilst at the same time protecting the benefits that artificial light at night may offer.…”