Exposure to Short Wavelength-Enriched White Light and Exercise Improves Alertness and Performance in Operational NASA Flight Controllers Working Overnight Shifts

Abstract

Objective: We evaluated the efficacy of a combined short-wavelength-enriched white light and exercise fatigue countermeasure during breaks for flight controllers working overnight shifts. Methods: Twenty NASA flight controllers were studied for two blocks of nightshifts in ISS mission control, randomized to either the control or countermeasure condition. The countermeasure constituted passive exposure to blue-enriched polychromatic lighting for three 20-minute intervals, which included 10 minutes of exercise and occurred before and twice during their shifts. Alertness, performance, and mood were evaluated. Results: Flight controllers reported being significantly more alert (P < 0.0001) and happy (P = 0.003) and had faster reaction times (10% slowest responses; P < 0.05) during the countermeasure condition compared to control. Conclusions: The combined light and exercise countermeasure improved alertness, performance, and mood in shift workers overnight. Further research is necessary to determine their relative contribution.

Effects of Lighting Interventions to Improve Sleepiness in Night-Shift Workers: A Systematic Review and Meta-Analysis

“…The lighting interventions in the experimental groups differed in lighting equipment, illuminance (in units of lux), lighting time points, exposure duration, spectrum wavelength, and color. Eight studies [ 22 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ] applied lighting with a color temperature greater than or equal to 5000 K and three applied lighting with a color temperature below 5000 K [ 33 , 34 , 35 ]. In terms of sleepiness assessment, 12 studies adopted the KSS [ 11 , 13 , 22 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 34 , 36 ], and 2 [ 33 , 37 ] adopted the Stanford Sleepiness Scale (SSS), as seen in Table 1 .…”

“…Of the 14 studies included in this review, 5 [ 22 , 27 , 33 , 36 , 37 ] found that lighting interventions significantly improved sleepiness, while 9 [ 11 , 13 , 16 , 26 , 29 , 30 , 31 , 32 , 34 ] indicated that lighting interventions had no significant effects in improving sleepiness. High heterogeneity was reflected by the I 2 of 78%.…”

“…Nine studies [ 16 , 26 , 29 , 30 , 31 , 32 , 34 , 36 , 37 ] showed that lighting interventions significantly (Z = 3.89, p = 0.0001) reduced the nighttime sleepiness of night-shift non-healthcare workers, with an SMD of −0.42 (95% CI: −0.64 to −0.21) and statistical heterogeneity being present (χ 2 = 11.28, p = 0.0001, Tau 2 = 0.03, I 2 = 29%). Five studies [ 11 , 13 , 22 , 27 , 33 ] also showed that lighting interventions significantly (Z = 2.16, p = 0.03) reduced the nighttime sleepiness of night-shift healthcare workers, with an SMD of −0.74 (95% CI: −1.40 to −0.07) and statistical heterogeneity being present (χ 2 = 40.16, p = 0.00001, Tau 2 = 0.52, I 2 = 90%; Figure 5 ).…”

“…Eight studies [ 16 , 22 , 26 , 27 , 29 , 30 , 31 , 32 ] showed that lighting with a color temperature greater than or equal to 5000 K significantly (Z = 4.41, p = 0.0001) improved the sleepiness of night-shift workers, with an SMD of −0.50 (95% CI: −0.72 to −0.28) and statistical heterogeneity being present (χ 2 = 9.91, p = 0.0003, Tau 2 = 0.03, I 2 = 29%). Three studies [ 11 , 33 , 34 ] showed that lighting with a temperature below 5000 K had no significant effect (Z = 1.35, p = 0.18) on sleepiness, with an SMD −0.84 (95% CI: −2.05 to 0.38) and statistical heterogeneity being present (χ 2 = 33.91, p = 0.00001, Tau 2 = 1.08, I 2 = 94%; Figure 6 ).…”

A Blue-Enriched, Increased Intensity Light Intervention to Improve Alertness and Performance in Rotating Night Shift Workers in an Operational Setting

“…[19][20][21][22] Few studies have directly tested the effectiveness of blue-enriched polychromatic light to enhance alertness and performance in a night shift work setting. [23][24][25][26] Based on the well-established principles that both intensity and spectral composition of light independently influence alertness state, 8,11,12 we evaluated the implementation of a control room lighting intervention on alertness, performance and mood during night shifts in rapidly rotating shift workers by increasing light intensity and blue light content as compared to the current lighting conditions. The intervention aimed to utilize the acute alerting effects of light directly during the night shifts, and not influence the circadian response to night shifts given that in rapidly rotating shift workers, circadian adaptation to consecutive night shifts is rare, 27 and is not advisable due to the quick return to day shifts.…”