Does Bright Light Counteract the Post-lunch Dip in Subjective States and Cognitive Performance Among Undergraduate Students?

Abstract

The post-lunch dip in alertness and performance was widely experienced during the early afternoon. Taking a short nap was documented as a practical strategy for habitual nappers to counteract the decline of alertness and performance. Yet, it remains unknown whether bright light exposure in the early afternoon working hours could alleviate the performance deficits caused by a post-lunch nap loss for habitual nappers. Seventeen undergraduate students who had a long-term habit of taking a post-lunch nap were assigned to three interventions: (1) a short nap + normal indoor light (100 lx, 4,000 K at eye level); (2) no nap + normal indoor light, and (3) no nap + blue-enriched bright light (1,000 lx, 6,500 K at eye level), in which subjective alertness (Karolinska Sleepiness Scale, KSS), mood (Positive and Negative Affect Schedule, PANAS), and task performance in sustained attention (psychomotor vigilance test, PVT), response inhibition (go/no-go task), and working memory (paced visual serial addition test, PVSAT) were measured. Results showed that a post-lunch nap deprivation significantly increased subjective sleepiness and negative mood and impaired performance in PVT and PVSAT, while exposure to bright blue-enriched white light vs. normal indoor light in the early afternoon significantly relieved such negative effects on mood, sleepiness, and performance in PVSAT; subjective positive mood and performance in PVT and go/no-go task remained unaffected with light intervention. These findings suggested that bright blue-enriched white light exposure could be a potential strategy for those who are suffering from drowsiness and low working memory following a habitual midday nap loss.

Quantitative indicators of street lighting with mood, fatigue, mental workload and sleepiness in car drivers: Using generalized structural equation modeling

“…The PANAS measures two subscales of positive emotion and negative emotion on a five-point likert scale from one (by no means) to five (very high). Cronbach’s alpha obtained is above 70% [ 27 ]. The SAMN-PERELLI has 17 questions and each question is based on a 5-point likert scale (1 = very low, 2 = low, 3 = medium, 4 = high, 5 = very high) [ 28 ].…”

Impact of repeated morning bright white light exposures on attention in a simulated office environment

“…Consistent with this finding, we measured light effects from 07:30 AM to 12:30 PM in our study. However, bright light exposure may also be effective in the afternoon (e.g., during the post-lunch dip 73 ). Fourth, the spectral composition of light was not changed throughout the study.…”

Diurnal effects of dynamic lighting on alertness, cognition, and mood of mentally fatigued individuals in a daylight deprived environment

“…The reason for this is that mental fatigue could reduce the effort of motivation, 12 which increases task difficulty perception sensitivity. The acute effects of daytime light on human working memory have been widely investigated in earlier SL studies; 17,20,61 however, it is questionable whether these results can be directly applied to DL scenarios, as previous studies have shown mixed results in n -back RT. Moreover, whether task difficulty moderates the effect of daytime light on working memory has been noted in the SL field.…”

“…19 Based on the conduction path, more and more studies proved that light, especially with high illumination or higher melanopic daylight efficacy ratio results in lower sleepiness and better performance. 20,21 However, the results of exposure to bright or short-wavelength light on alertness, cognition and mood are mixed, which may be affected by mental antecedent conditions. Šmotek et al 22 revealed that short-wavelength light (λ max = 455 nm) during the day may enhance alertness and cognitive performance in healthy adults.…”