Tabriz University of Medical Sciences Health Promotion Perspectives 2228-6497 16 3 2026 11 05 Gender Differences in the Effects of Adaptive Lighting on Heart Rate Variability and Cognitive Performance Among Night-Shift Nurses: A Between-Subjects Factorial Study 406 421 10.34172/hpp.45239 EN Somayeh Bolghanabadi https://orcid.org/0000-0003-0046-1512 Alireza Choobineh https://orcid.org/0000-0002-0866-0404 Saeedeh Pourahmad https://orcid.org/0000-0002-7366-1059 Ramazan Mirzaei https://orcid.org/0000-0003-1468-8910 Muslem Alimohammadlou Reza Kazemi https://orcid.org/0000-0003-1361-7360 Journal Article 10.34172/hpp.45239 2025 09 24 2026 05 25 Introduction: Night-shift work disrupts circadian rhythms and exposes nurses to inadequate lighting, negatively affecting cognitive performance and physiological health. Circadian rhythm interventions, particularly those adapted to sex-specific responses, may help mitigate these risks. This study examined the effects of correlated color temperature (CCT), light intensity, and exposure duration on heart rate variability (HRV) and sustained attention in night-shift nurses, emphasizing gender differences. Methods: Sixty-four nurses (32 men and 32 women) participated under controlled environmental conditions (22–24°C) with ergonomic seating. No randomization was performed for participant allocation, lighting condition, session timing, or condition sequence. Participants were allocated to eight experimental lighting conditions, with eight participants (four men and four women) in each condition. The lighting intervention consisted of eight conditions combining light intensities (500 and 1000 lux), CCT levels (3000 K and 6500 K), and exposure durations (10 and 20 minutes). The study used a 2×2×2 between-subjects factorial design, and each participant was exposed to only one lighting condition. Experimental sessions were conducted between 11:00 PM and 1:00 AM. HRV indices and cognitive performance (2-back task, Psychomotor Vigilance Test) were measured before and after exposure. Changes from baseline to post-exposure were analyzed using three-way ANOVA to examine the effects of illuminance, CCT, and exposure duration, with appropriate non-parametric tests used for non-normally distributed outcomes. Statistical significance was set at P<0.05. Results: Different lighting conditions elicited distinct autonomic responses according to sex. In women, CCT had significant effects on HR and SDNN, whereas in men, CCT significantly affected HR, SDNN, and RMSSD (P<0.05). In addition, several significant interactions among lighting parameters were observed for HRV indices(P<0.05), with effect sizes (η²) ranging from 0.17 to 0.45. Cognitive performance and sustained attention showed minor variations across lighting conditions; however, no significant main or interaction effects were observed for these variables (P>0.05). Conclusion: These findings suggest that lighting characteristics may differentially affect autonomic responses during night-shift work according to sex. However, no significant effect on cognitive performance was observed, and larger studies are needed to confirm these findings.