Year: 2012
Type: conference-paper
Abstract: Humans evolved as a diurnal species, functioning primarily during the daytime hours of the Earth’s light-dark cycle with concomitant sleep-wake cycles that are governed by circadian and homeostatic processes. In contrast to our evolutionary ancestors, the behavioral settings in which most modern humans perform many workrelated tasks exist indoors and under artificial lighting; as light plays an important role in regulating physiological processes in humans, researchers are increasingly interested in exploring the effects of light in these settings. Research on effects of bright light during the night has rendered convincing evidence that light can elicit phase-shifting effects on the biological clock, increase nocturnal alertness and improve cognitive task performance (Cajochen, Zeitzer, Czeisler & Dijk, 2000; Campbell & Dawson, 1990; Ruger, Gordijn, de Vries & Beersma, 2006). Studies investigating such effects during daytime is more scarce, yet is also starting to show statistically significant effects on subjective as well as objective (physiology, task performance) indicators of alertness (Phipps-Nelson, Redman, Dijk & Rajaratman, 2003; Ruger et al., 2006; Smolders, de Kort & Cluitmans, 2012). The latter study showed that even under natural, i.e. non sleep or light-deprived conditions, a higher illuminance (1000 lx at eye level) can improve feelings of alertness and vitality, cognitive task performance, and influence physiological arousal during daytime. Several mechanisms by which light might influence alertness and performance during daytime have been proposed (Rautkyla, Puolakka & Halonen, 2011; Stephenson, Schroder, Bertschy & Bourgin, 2012; Vandewalle et al., 2009). A possible mechanism for the alerting and vitalizing effects of light might be the activation and modulation of alertness-related and moodrelated pathways also referred to as nonvisual pathways. In addition, beliefs or expectations regarding effects of bright light may contribute to these effects. Thus, the effect can be purely biological, i.e. through activation of the central nervous system (Vandewalle et al., 2009), but could also be more psychological in nature – i.e. via the visual pathway, involving appraisal and affective routes (e.g. Veitch, Newsham, Boyce & Jones, 2008), or beliefs about activating effects of more intense light. These psychological pathways are relevant to design and theory, but also have methodological implications as participants in lighting studies are only rarely ‘blind’ to the light manipulation. The current study was designed to test the effect of light via purely psychological (visual) pathways: we tested alertness and performance of participants who were offered different lighting scenarios, suggesting that the light was stable, increasing, or decreasing steadily, although in fact they were receiving equal amounts of light. We expected that if appreciation and/or beliefs play an important role in the beneficial effect of light, ostensibly increasing the intensity would affect alertness and performance more positively than exposure to a constant lighting scenario or ostensibly decreasing lighting scenario would. If, in contrast, the number of photons at the retina is the sole responsible cause, we would see no differences between the three lighting scenarios as participants in all conditions experienced the same light dosage.
Source: TU/e Research Portal
Authors: K.C.H.J. Smolders, Andrea Antal, Ashley Corona, Mathieu Heijboer, Edward J. Keyes, Kathrin Pollmann, de Y.A.W. Kort
Language: English
Subfield: Endocrine and Autonomic Systems
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W64556288