Effects of bright light and an afternoon nap on task performance depend on the cognitive domain

Abstract

Previous research revealed inconsistent effects of bright light or a short nap at noon on alertness and performance across different tasks. The current study aimed to explore whether the effects of bright light and a short nap at noon on task performance depended on the cognitive domain. Bright light (1,200 lx, 4,000 K at eye level), nap (near darkness) and control (200 lx, 4,000 K at eye level) conditions were performed from 1:00 to 1:40 PM on three non‐consecutive days with a counterbalanced order across participants. After being assigned to one of three conditions, participants underwent two repeated test sessions, each including a psychomotor vigilance task, a go/no‐go task, and a paced visual serial addition task, with an interval of more than 1 h, to assess the persistent effects of napping and bright light. Subjective sleepiness, vitality, self‐control and mood were also measured. Results showed that accuracy on the go/no‐go task and the paced visual serial addition task improved significantly throughout the entire experiment session after napping, whereas reaction speed on the paced visual serial addition task improved time‐dependently in the bright light intervention, with a higher reaction speed in only the first test session. Nearly all subjective states benefited from napping but not from bright light. These findings suggested that the effects of bright light and an afternoon nap on task performance would depend on the cognitive domain. An afternoon nap may elicit more effective and persistent benefits on task performance and subjective states.

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

“…Regarding the task performance, the previous studies had revealed no consistent pattern of a post-lunch nap on task performance varied in different cognitive domains (5,9,10,23,59). The current findings even revealed an indicator and type of task-dependent impairment of nap deprivation on cognitive performance.…”

“…Effects of a nap deprivation on mood were scarcely investigated in previous studies, except one earlier study by Caldwell and Caldwell ( 58 ) suggesting beneficial effects of a post-lunch nap on mood. One recent study by Qian et al ( 59 ) reported that participants who took a short midday nap felt happier than those who stayed awake during post-lunch dip period. Similar to the case of subjective sleepiness, the current study revealed exposure to bright blue-enriched white light in the early afternoon would relieve habitual nappers' negative mood stimulated by nap deprivation.…”

Hypoxia Differentially Affects Healthy Men and Women During a Daytime Nap With a Dose-Response Relationship: a Randomized, Cross-Over Pilot Study

“…Our results are more in agreement with Latshang et al (2013) who also failed to evoke changes. Additionally, although it has been shown that after naps there is an enhancement of mental activity ( Milner and Cote, 2009 ; Qian et al, 2020 ), our results only showed a slight improvement in cognitive performance. It is possible that, as has been proposed ( McMorris et al, 2017 ), changes become apparent only when arterial oxygen delivery is below a certain threshold.…”

Effects of Ambient Illuminance on Explicit and Implicit Altruism: The Mediation Roles of Perceived Anonymity and Satisfaction with Light

“…Previous studies have also shown that individuals with high self-control ability were inclined to act in a more other-interested manner than those with low self-control ability [ 37 , 38 ], and this pattern was reversed when faced with crisis situations [ 39 ]. The effects of ambient light on state self-control were occasionally reported in previous studies [ 29 , 35 , 40 , 41 , 42 ]. For example, exposure to bright versus dim illuminance (1500 lx vs. 150 lx) could increase participants’ public self-awareness and lead to controlled self-regulation [ 35 ].…”