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We investigated whether learning performance in a procedural finger tapping task before nocturnal sleep would predict performance gains after sleep in 60 young adults. Gains were defined as change in correctly tapped digit sequences between learning (12 trials administered in the evening) and retesting (3 trials administered in the morning after sleep). The same task was also administered to a separate wake group (N = 54 young adults), which learned in the morning and was retested in the evening. Learning performance was determined by either using the average performance on the last three learning trials or the average performance on the best three learning trials. Our results demonstrated an inverse association between learning performance and gains in procedural skill, i.e., good learners exhibited smaller performance gains across both wakefulness and sleep than poor learners. Regardless of learning performance, gains in finger tapping skills were greater after sleep than daytime wakefulness. Importantly, some of our findings were influenced by how learning performance was estimated. Collectively, these results suggest that learning performance and the method through which it is estimated may influence performance gains in finger tapping skills across both sleep and wakefulness.

Monetary reward and video-based praise following training of a motor skill result in greater gains in the skill. Whether this could also be achieved by text-only praise after learning is unclear. Neither is it known whether the effects of praise on subsequent consolidation of motor memories depend on the learner’s competence-based self-esteem. A high competence-based self-esteem is defined by one’s abilities, constituting a fragile basis for feelings of self-worth, and correlates with a lower intrinsic self-esteem.

In the present study, seventy-eight subjects performed a motor task where they tapped a digit sequence (on a laptop) as fast and accurate as possible at three separate sessions: learning (scheduled in the evening on the training day), short-term recall (12 hours later), and long-term recall (~30 days later). Immediately after learning, all participants of the PRAISE group (n=39) were given a text praise, whereas those of the NO PRAISE group were not. Our results demonstrate that praise overall resulted in greater post-training gains in finger skill compared with no praise (P<0.05, ~ +6%). We also found that those with low scores on the competence-based self-esteem scale (i.e., likely to have a high intrinsic self-esteem) showed more pronounced post-training gains in finger skill than those with higher scores (P<0.05). However, competence-based self-esteem did not change the effect of praise on offline gains in finger skill (P>0.05). If confirmed by future studies, our findings could suggest that praise and a person’s self-esteem can contribute to variance in post-training improvements of motor skill.

Acute sleep deprivation can lead to judgement errors and thereby increases the risk of accidents, possibly due to an impaired working memory. However, whether the adverse effects of acute sleep loss on working memory are modulated by auditory distraction in women and men are not known. Additionally, it is unknown whether sleep loss alters the way in which men and women perceive their working memory performance. Thus, 24 young adults (12 women using oral contraceptives at the time of investigation) participated in two experimental conditions: nocturnal sleep (scheduled between 22:30 and 06:30 hours) versus one night of total sleep loss. Participants were administered a digital working memory test in which eight-digit sequences were learned and retrieved in the morning after each condition. Learning of digital sequences was accompanied by either silence or auditory distraction (equal distribution among trials). After sequence retrieval, each trial ended with a question regarding how certain participants were of the correctness of their response, as a self-estimate of working memory performance. We found that sleep loss impaired objective but not self-estimated working memory performance in women. In contrast, both measures remained unaffected by sleep loss in men. Auditory distraction impaired working memory performance, without modulation by sleep loss or sex. Being unaware of cognitive limitations when sleep-deprived, as seen in our study, could lead to undesirable consequences in, for example, an occupational context. Our findings suggest that sleep-deprived young women are at particular risk for overestimating their working memory performance.

Background: The use of electronic devices emitting blue light during evening hours has been associated with sleep disturbances in humans, possibly due to the blue light-mediated suppression of the sleep promoting hormone melatonin. However, experimental results have been mixed. The present study therefore sought to investigate if reading on a self-luminous tablet during evening hours would alter sleepiness, melatonin secretion, nocturnal sleep, as well as electroencephalographic power spectral density during early slow-wave sleep. Methods: Following a constant bright light exposure over 6.5 hours (similar to 569 lux), 14 participants (six females) read a novel either on a tablet or as physical book for two hours (21:00-23:00). Evening concentrations of saliva melatonin were repeatedly measured. Sleep (23:15-07:15) was recorded by polysomnography. Sleepiness was assessed before and after nocturnal sleep. About one week later, experiments were repeated; participants who had read the novel on a tablet in the first experimental session continued reading the same novel in the physical book, and vice versa. Results: There were no differences in sleep parameters and pre-sleep saliva melatonin levels between the tablet reading and physical book reading conditions. Conclusions: Bright light exposure during daytime has previously been shown to abolish the inhibitory effects of evening light stimulus on melatonin secretion. Our results could therefore suggest that exposure to bright light during the day - as in the present study - may help combat sleep disturbances associated with the evening use of electronic devices emitting blue light. However, this needs to be validated by future studies with larger sample populations.