Citation

Weng M, Schöllhorn I, Kazhura M, Cardini BB, Stefani O. Clocks Sleep 2022; 4(4): 607-622.

Copyright

(Copyright © 2022, MDPI: Multidisciplinary Digital Publications Institute)

DOI

10.3390/clockssleep4040047

PMID

36412580

Abstract

Future automotive interior lighting might have the potential to go beyond decorative purposes by influencing alertness, circadian physiology, and sleep. As the available space in the interior of an automobile for lighting applications is limited, understanding the impact of various luminous surface sizes on non-image-forming effects is fundamental in this field. In a laboratory study using a within-subject design, 18 participants were exposed to two bright light conditions with different solid angles and one dim light condition in a balanced, randomized order during the course of the evening. Our results demonstrate that both light conditions significantly increased subjective alertness and reduced salivary melatonin concentration but not cognitive performance compared to dim light. The solid angle of light exposure at constant corneal illuminance only affected visual comfort. While subjective alertness can be increased and melatonin can be attenuated with rather small luminaires, larger solid angles should be considered if visual comfort is a priority.

Language: en

Keywords

automotive interior lighting; bright light exposure; cognitive alertness; luminous surface size; non-image-forming; non-visual effects; salivary melatonin; solid angle; subjective alertness