Acute alerting effects of light: A systematic literature review

Facebook use and sleep quality: Light interacts with socially induced alertness

“…The effect of light in the blue part of the spectrum on sleepiness is not as robust as often assumed (Souman et al, 2018). The first is whether the study had sufficient power to detect main effects of 'Light' or 'Arousal' if they were there.…”

“…Nonetheless, given that earlier studies (Cajochen et al, 2011) have shown that filtering blue light changes melatonin levels and can change measures of sleepiness, the credibility of the null result of varying the light is worth further consideration. This is plausible given the large proportion of studies that did not find a significant effect of manipulating the blue light content of the spectrum (Souman et al, 2018). However, to explore whether the study had sufficient power, a power analysis with the program G*Power (Faul, Erdfelder, Lang, & Buchner, 2007) was conducted to evaluate sample sizes sufficient to detect changes in sleep quality.…”

“…Sample size had been chosen based on previous studies using the PSQI (Gross, Kreitzer, Russas, & Treesak, 2004;Lai & Good, 2005;Sun, Kang, Wang, & Zeng, 2013;Yook et al, 2008). Souman et al (2018) suggest a sample of n > 155. Given an alpha of p < .05, desired power of .90 and moderate effect sizes (0.06) gives a power of .91 for a sample size of 30 participants.…”

0145 The Acute Effects of Intermittent Light Exposure in The Evening on Alertness and Subsequent Sleep Architecture

“…Recently, mounting studies have examined the effects of light on subjective and objective alertness and have consistently found that exposure to light can enhance alertness [11][12][13]. For example, in the evening, exposure to monochromatic light at 460 nm for two hours induced greater subjective alertness and reduced sleepiness when compared to 550 nm exposure [14].…”

“…For example, in the evening, exposure to monochromatic light at 460 nm for two hours induced greater subjective alertness and reduced sleepiness when compared to 550 nm exposure [14]. Additionally, in the daytime, the participants felt less sleepy and had shorter reaction times on the psychomotor vigilance task (PVT, a simple reaction time task) [13,15,16] during exposure to light (correlated color temperature: 4000 K) of 1000 lux when compared with light (4000 K) of 200 lux [17]. Furthermore, functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) studies that aimed to explore the mechanisms underlying the acute effects of light on alertness confirmed that light exposure modulated alertness-related subcortical structures (hypothalamus, brainstem, thalamus) [18][19][20][21][22].…”