The evidence on the short-term effects of light on cognition is inconsistent. Within the framework of the human-centric lighting approach, such effects could be used to enhance well-being and performance. To address this question, we conducted a one hour laboratory study with 789 participants, examining the impact of bright daylight white light (BL; 517.0 lx, 5417 K), warm-white light (WL; 67.5 lx, 2628 K), and neutral light (NL; 160.8 lx, 4133 K) on the scales of the Attention Network Test (ANT). The effects observed were small in magnitude. For your attention, only a small, insignificant effect emerged, with WL yielding the poorest performance. In contrast, the scale alerting showed a significant medium effect, with fastest responses under BL and slowest under WL. For the scale orienting, a small significant effect was found, with WL producing the best performance. BL emerged as the most beneficial condition overall, particularly enhancing the alerting component. In contrast, WL was repeatedly associated with negative effects on both scales alerting and executive attention. Unexpectedly, WL showed advantages in the orienting component, suggesting complex underlying mechanisms that are not yet fully understood. Future studies should examine lighting programs with greater contrast and incorporate physiological measures (e.g., pupillometry, EEG) as well as more differentiated psychological assessments. To explain these findings, the development of integrative models - such as the HCL-effect model proposed by Wessolowski - is essential. Light is more than a visual stimulus; it modulates attention and cognition. This insight should be systematically considered in the design of work, learning, and living environments.

The estrous cycle of female guinea pigs is characterized by a spontaneous ovulation and a subsequent active luteal phase that is physiologically well described. In contrast to other rodents, however, the effects of the cycle on stress responses and behavior are understudied in this species. This study examines the extent to which cortisol concentrations and behavior differ between the estrus and diestrus phases of two consecutive cycles in twelve female guinea pigs. In addition, the parameters were analyzed regarding repeatability to determine how far both physiological parameters and behavior are individually consistent throughout the cycle. Saliva samples to analyze cortisol concentrations were collected before and after a 15-minute dark-light test. The dark-light test and a 15-min sociality test were performed to analyze exploration, anxiety, and social interest. Cortisol concentrations were increased in estrus compared to diestrus. In the dark-light test, the cycle phase had no significant influence on locomotion or anxiety-like behavior. Locomotion and time spent with a conspecific in the sociality test were partly increased in estrus compared to diestrus. All behaviors were repeatable throughout the two investigated cycles. The results show that the estrous cycle of female guinea pigs can influence physiology and behavior to some extent, but that individual differences have a stronger influence on behavior than does the cycle. These findings contribute to the general understanding of physiological and behavioral changes during the estrous cycle, which are understudied not only in guinea pigs but in many mammalian species.