Peek At Science: 2023 January 24

Peak At Science 20230117
Quantum Biology

Peek At Science: 2023 January 24

Blue light from light-emitting diodes elicits a dose-dependent suppression of melatonin in humans

Light suppresses melatonin in humans, with the strongest response occurring in the short-wavelength portion of the spectrum between 446 and 477 nm that appears blue. Blue monochromatic light has also been shown to be more effective than longer-wavelength light for enhancing alertness. Disturbed circadian rhythms and sleep loss have been described as risk factors for astronauts and NASA ground control workers, as well as civilians. Such disturbances can result in impaired alertness and diminished performance. Prior to exposing subjects to short-wavelength light from light-emitting diodes (LEDs) (peak λ = 469 nm; 1⁄2 peak bandwidth = 26 nm), the ocular safety exposure to the blue LED light was confirmed by an independent hazard analysis using the American Conference of Governmental Industrial Hygienists exposure limits. Subsequently, a fluence-response curve was developed for plasma melatonin suppression in healthy subjects (n = 8; mean age of 23.9 ± 0.5 years) exposed to a range of irradiances of blue LED light. Subjects with freely reactive pupils were exposed to light between 2:00 and 3:30 AM. Blood samples were collected before and after light exposures and quantified for melatonin. The results demonstrate that increasing irradiances of narrowband blue-appearing light can elicit increasing plasma melatonin suppression in healthy subjects (P < 0.0001). The data were fit to a sigmoidal fluence-response curve (R2 = 0.99; ED50 = 14.19 μW/cm2 ). A comparison of mean melatonin suppression with 40 μW/cm2 from 4,000 K broadband white fluorescent light, currently used in most general lighting fixtures, suggests that narrow bandwidth blue LED light may be stronger than 4,000 K white fluorescent light for suppressing melatonin.



光はヒトのメラトニンを抑制し、最も強い反応を示すのは、青く見える446477nmの短波長部分である。また、青色単色光は、長波長光よりも覚醒度を高める効果があることが分かっています。概日リズムの乱れや睡眠不足は、宇宙飛行士や NASA の地上管制官、そして一般市民の危険因子として指摘されている。このような乱れは、覚醒度の低下やパフォーマンスの低下を招く可能性がある。発光ダイオード(LED)の短波長光(ピークλ469nm1/2ピーク帯域幅=26nm)を被験者に照射する前に、米国産業衛生専門家会議の暴露限界を用いた独自のハザード分析により、青色LED光に対する眼の安全性が確認された。その後,健康な被験者(n = 8,平均年齢 23.9 ± 0.5歳)を対象に,さまざまな照射量の青色LED光に曝露して血漿メラトニン抑制のフルエンス反応曲線を作成した。自由反応性瞳孔を持つ被験者は、午前2時から330分の間に光を照射された。光照射の前後に血液サンプルを採取し、メラトニンを定量化した。その結果、狭帯域青色光の照射量が増加すると、健康な被験者において血漿メラトニンの抑制が増加することが示された(P < 0.0001)。データは、シグモイド型フルエンス反応曲線に適合した(R2 = 0.99; ED50 = 14.19 μW/cm2 )。現在、一般的な照明器具で使用されている4,000K広帯域白色蛍光灯の40μW/cm2と比較すると、狭帯域青色LED光は4,000K白色蛍光灯よりもメラトニンを抑制する力が強い可能性が示唆された。

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