6 research outputs found

    Blue light exposure reduces objective measures of sleepiness during prolonged nighttime performance testing

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    \u3cp\u3eThis study examined the effects of nocturnal exposure to dim, narrowband blue light (460 nm, ̃1 lux, 2 μW/cm\u3csup\u3e2\u3c/sup\u3e), compared to dim broad spectrum (white) ambient light (̃0.2 lux, 0.5 μW/cm\u3csup\u3e2\u3c/sup\u3e), on subjective and objective indices of sleepiness during prolonged nighttime performance testing. Participants were also exposed to a red light (640 nm, ̃1 lux, 0.7μW/cm\u3csup\u3e2\u3c/sup\u3e) placebo condition. Outcome measures were driving simulator and psychomotor vigilance task (PVT) performance, subjective sleepiness, salivary melatonin, and electroencephalographic (EEG) activity. The study had a repeated-measures design, with three counterbalanced light conditions and a four-week washout period between each condition. Participants (n = 8) maintained a regular sleep-wake schedule for 14 days prior to the ̃14 h laboratory study, which consisted of habituation to light conditions followed by neurobehavioral performance testing from 21:00 to 08:30 h under modified constant-routine conditions. A neurobehavioral test battery (2.5 h) was presented four times between 21:00 and 08:30 h, with a 30 min break between each. From 23:30 to 05:30 h, participants were exposed to blue or red light, or remained in ambient conditions. Compared to ambient light exposure, blue light exposure suppressed EEG slow wave delta (1.0-4.5 Hz) and theta (4.5-8 Hz) activity and reduced the incidence of slow eye movements. PVT reaction times were significantly faster in the blue light condition, but driving simulator measures, subjective sleepiness, and salivary melatonin levels were not significantly affected by blue light. Red light exposure, as compared to ambient light exposure, reduced the incidence of slow eye movements. The results demonstrate that low-intensity, blue light exposure can promote alertness, as measured by some of the objective indices used in this study, during prolonged nighttime performance testing. Low intensity, blue light exposure has the potential to be applied to situations where it is desirable to increase alertness but not practical or appropriate to use bright light, such as certain occupational settings.\u3c/p\u3

    Prevalence of probable shift work disorder in non-standard work schedules and associations with sleep, health and safety outcomes: A cross-sectional analysis

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    Purpose: We aimed to estimate the prevalence of probable shift work disorder (pSWD) in a representative sample of Australian workers and identify sleep, health and safety correlates. Patients and Methods: In 2019, data were collected from working respondents as part of a cross-sectional national sleep health survey conducted online (n=964 total; n=448 individuals on non-standard work schedules). We established the prevalence of pSWD according to International Classification of Sleep Disorders criteria (ICSD-R, ICSD-2 and ICSD-3). Poisson regression was used to determine crude and adjusted prevalence association (prevalence ratio, PR) of pSWD with sleep, health and safety outcomes. Results: Overall prevalence of pSWD in workers on non-standard work schedules was 10.5%, ranging from 9.6% in early morning workers to 12.7% in rotating shift workers. In adjusted models, workers who met the criteria for pSWD were 1.8 times more likely to report both depression/bipolar disorder, and anxiety/panic disorder, and 1.7 times more likely to report work errors due to a sleep problem. Conclusion: The prevalence of pSWD in employees engaged in non-standard work schedules is influenced by selection of factors used to quantify pSWD, including sleep/wake patterns. Higher likelihoods of mental health problems and workplace errors in those with pSWD highlight the importance of intervention and management of this under-recognised sleep disorder

    A blue-enriched, increased intensity light intervention to improve alertness and performance in rotating night shift workers in an operational setting

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    Purpose: This study examined the efficacy of a lighting intervention that increased both light intensity and short-wavelength (blue) light content to improve alertness, performance and mood in night shift workers in a chemical plant. Patients and Methods: During rostered night shifts, 28 workers (46.0± 10.8 years; 27 male) were exposed to two light conditions each for two consecutive nights (∼ 19:00– 07:00 h) in a counterbalanced repeated measures design: traditional-spectrum lighting set at pre-study levels (43 lux, 4000 K) versus higher intensity, blue-enriched lighting (106 lux, 17,000 K), equating to a 4.5-fold increase in melanopic illuminance (24 to 108 melanopic illuminance). Participants completed the Karolinska Sleepiness Scale, subjective mood ratings, and the Psychomotor Vigilance Task (PVT) every 2– 4 hours during the night shift. Results: A significant main effect of time indicated KSS, PVT mean reaction time, number of PVT lapses (reaction times > 500 ms) and subjective tension, misery and depression worsened over the course of the night shift (p 0.05). Conclusion: Our findings, showing improvements in alertness and performance with exposure to blue-enriched, increased intensity light, provide support for light to be used as a countermeasure for impaired alertness in night shift work settings
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