Light level and duration of exposure determine the impact of self-luminous tablets on melatonin suppression
Lighting Research Center, Rensselaer Polytechnic Institute, 21 Union Street, Troy, NY 12180, USA.Applied ergonomics (Impact Factor: 2.02). 07/2012; 44(2). DOI: 10.1016/j.apergo.2012.07.008
Exposure to light from self-luminous displays may be linked to increased risk for sleep disorders because these devices emit optical radiation at short wavelengths, close to the peak sensitivity of melatonin suppression. Thirteen participants experienced three experimental conditions in a within-subjects design to investigate the impact of self-luminous tablet displays on nocturnal melatonin suppression: 1) tablets-only set to the highest brightness, 2) tablets viewed through clear-lens goggles equipped with blue light-emitting diodes that provided 40 lux of 470-nm light at the cornea, and 3) tablets viewed through orange-tinted glasses (dark control; optical radiation <525 nm ≈ 0). Melatonin suppressions after 1-h and 2-h exposures to tablets viewed with the blue light were significantly greater than zero. Suppression levels after 1-h exposure to the tablets-only were not statistically different than zero; however, this difference reached significance after 2 h. Based on these results, display manufacturers can determine how their products will affect melatonin levels and use model predictions to tune the spectral power distribution of self-luminous devices to increase or to decrease stimulation to the circadian system.
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- "Contemporary sleep guidelines dictate that the average adolescent requires between 8.5 and 9.25 h of nocturnal sleep (Carskadon et al. 1980; Matricciani et al. 2013) for optimal health, cognitive, physical, psychological and behavioural outcomes (Auvinen et al. 2010; Matthews et al. 2012; Vriend et al. 2013; Wong, Lau et al. 2013). However, factors, such as a reduced parental influence on bedtime, early waketimes due to schooling commitments and the use of stimulating technological devices prior to bedtime, are all known to lead to the loss of sleep in adolescents (Crowley et al. 2007; Wood et al. 2013). In addition, research on brain maturation indicates a natural increase in daytime sleepiness during adolescence, due to reductions in slow wave sleep and waking brain activity, that is independent of the amount of sleep obtained (Campbell et al. 2007). "
ABSTRACT: Adolescents are predisposed to poorer quality of sleep and experience shortened sleep durations, with these trends being more pronounced amongst Asians. Even though sleep is crucial for athletic recovery, there is a dearth of the literature on the sleep patterns of Asian adolescent athletes. The purpose of this study was to examine the effects of different intensities of sports training on sleep patterns in adolescent athletes, and to describe novel sleep data and daytime sleepiness amongst Asian adolescents who were high-level athletes. Those athletes (age 14.8 ± 0.9 years) in higher-intensity sports showed significantly more deep sleep, less light sleep and waketime after sleep onset. Actigraphically determined bedtimes and waketimes were significantly delayed on weekends, when mean total sleep time was also significantly longer. There was a large effect for an increased daytime sleepiness in high-intensity sport athletes. These findings highlight the phenomenon of social jet lag in Asian adolescent student-athletes.
- "Many adolescents now use IPADs for reading and game play. Researchers have shown that the blue light from self-luminous tablets can have a negative effect on natural melatonin production and thus disrupt sleep (Wood, Rea, Plitnick, & Figueiro, 2013). "
Chapter: Sleep-Wake and Somatic Disorders
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- "In addition, tailored interventions to reduce especially short wavelength (blue) light in the evenings and/or to increase light exposure in the mornings could help to synchronize the students' circadian clocks to their school schedules. The circadian clock is most sensitive to short wavelengths (Brainard et al., 2001), and studies have shown that especially blue light from computers and televisions interferes with sleep and the circadian rhythm (Wood et al., 2013; van der Lely et al., 2014). However, such behavioral interventions are as difficult to achieve on a population level, as are changes in school start times. "
ABSTRACT: Circadian clocks of adolescents typically run late – including sleep times – while adolescents generally are expected at school early in the morning. Due to this mismatch between internal (circadian) and external (social) times, they suffer from chronic sleep deficiency, which, in turn, affects academic performance negatively. This constellation impacts students’ future career prospects. Our study correlates chronotype and exam performance. In total, 4,734 grades were collected from 741 Dutch high school students (ages 11-18 yrs) who had completed the Munich ChronoType Questionnaire (MCTQ) to estimate their internal time. Overall, the lowest grades were obtained by students who were very late chronotypes (MSFsc > 5.31 h) or slept very short on schooldays (SDw < 7.03 h). The effect of chronotype on exam performance depended on the time of day that exams were taken. Opposed to late types, early chronotypes obtained significantly higher grades during the early (8:15-9:45) and late (10:00-12:15) morning. This group difference in grades disappeared in the early afternoon (12:45-15:00). Late types also obtained lower grades than early types when tested at the same internal time (hours after MSFsc), which may reflect general attention and learning disadvantages of late chronotypes during the early morning. Our results support delaying high school starting times as well as scheduling exams in the early afternoon to avoid discrimination of late chronotypes, and to give all high school students equal academic opportunities.
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