The present study examined whether a nap after complex motor learning enhanced the following day's physical performance. Eighteen volunteers met the inclusion criteria and were assigned to either a nap (n=9; men=5; mean age=21.0±1.5) or no-nap group (n=9; men=5; mean age=21.9±0.3). Participants practiced juggling in the morning and were tested immediately afterwards. Participants of the nap group were given a 70-minute nap opportunity after juggling practice, while the no-nap group stayed awake. Juggling performance was then tested in the evening (retest-1) and the next morning (retest-2). Two-way analysis of variance (group: nap, no-nap×time: test, retest-1, retest-2) found there was a significant effect of test time and a significant group×time interaction. The juggling performance of both groups improved from test to retest-1, respectively. However, the juggling performance level of the nap group was higher than that of the no-nap group at the retest-1. As predicted, a nap promptly after learning motor skills was associated with subsequently improved performance. Moreover, the juggling performance of the nap group showed additional significant improvements in the retest-2. In the no-nap group, however, there were no significant improvements in the juggling performance after nocturnal sleep. These results demonstrate that the benefits of a nap following learning were further enhanced after nocturnal sleep. The present results may provide justification for introducing nap periods into daily athletic training as an active method to improve performance.

This study examined hypotheses regarding dreaming in rapid eye movement (REM) sleep by comparing brain potentials related to rapid eye movements in REM sleep with those in wakefulness. Within participants. Data were collected in a sleep laboratory. Fifteen healthy university students who reported having dreams frequently. Rapid eye movements in REM sleep were recorded during natural nocturnal sleep. Saccades in wakefulness were recorded during a self-paced visual search task. The presaccadic negativity before and the lambda response after eye movements were examined. It was assumed that the presaccadic negativity reflects voluntary readiness activity before eye movements, and the lambda response reflects visual information processing after saccades in wakefulness. Brain potentials were averaged, time-locked to the onset and offset of eye movements for the presaccadic negativity and the lambda response, respectively. In wakefulness, the presaccadic negativity occurred at the centroparietal site. However, no presaccadic negativity was found during REM sleep. Lambda-like responses (P1r, P2r) were observed in REM sleep over the parietooccipital site, as were the lambda responses (P1, P2) in wakefulness. The finding that rapid eye movements are initiated without preparation but elicit some neural activity in the cortical visual area suggests that rapid eye movements may trigger dream images.

Self-awakening, waking up at a designated time decided before sleeping, could prevent failure in the blood circulation vessel system such as heart attack, acute increases in heart rate or blood pressure upon waking. Previous research showed that anticipatory changes occurred in heart rate prior to awakening from a short nap by means of self-awakening for young participants. However, the effects of self-awakening remained unclear for elderly people. The present study examined the effects of self-awakening on heart rate and blood pressure in a short afternoon nap (20 min) among the elderly. Nine participants [74.1 (SD = 5.01) years old] underwent both self-awakening and forced-awakening conditions. In the self-awakening condition, it was revealed that blood pressure gradually increased before the scheduled time of awakening, and that heart rate did not show a rapid increase at arousal. In contrast, forced-awakening induced acute increases in both heart rate and blood pressure. These results suggest that self-awakening facilitates a more smooth transition from sleep to wakefulness via autonomic activation before the time of self-awakening.

Research shows that human attentional focus expands under positive emotions and narrows under negative emotions. Moreover, expanding (or contracting) the attentional focus is associated with dispersing (or concentrating) attentional resources. This study investigated whether dispersing or concentrating attentional resources on a target stimulus can change negative emotions to positive ones. We used the flanker task to manipulate the attentional resource allocation range by displaying a peripheral, task-unrelated induction stimulus far from the target stimulus or a central, task-unrelated induction stimulus near the target stimulus. The attentional resources allocated to the target stimulus were measured by recording the P300 component, an event-related potential indicating attention allocation. We also presented negative images before and after the task and used the Self-Assessment Manikin and the Affect Grid to assess the negative emotions induced by the images. The P300 amplitudes for the target stimuli were smaller in the peripheral than in the central condition. Moreover, self-reported negative emotions in the peripheral condition decreased after the task but did not change in the central condition. The dispersion of attentional resources changes negative emotions into a positive orientation.

We aimed to evaluate sleep and sleep-related physiological parameters (heart rate variability and glucose dynamics) among evacuees by experimentally recreating the sleep environment of evacuation shelters and cars. Nine healthy young male subjects participated in this study. Two interventions, modeling the sleep environments of evacuation shelters (evacuation shelter trial) and car seats (car trial), were compared with sleep at home (control trial). Physiological data were measured using portable two-channel electroencephalogram and electrooculogram monitoring systems, wearable heart rate sensors, and flash glucose monitors. Wake after sleep onset (WASO) and stage shift were greater in both intervention trials than the control trial, while rapid-eye movement (REM) latency and non-rapid eye movement (NREM) 1 were longer and REM duration was shorter in the evacuation shelter trial than the control trial. Glucose dynamics and power at low frequency (LF.p) of heart rate variability were higher in the car trial than in the control trial. It was confirmed that sleep environment was important to maintain sleep, and affected glucose dynamics and heart rate variability in the experimental situation.

Background: Many people use the snooze function of digital alarm clocks for morning awakening, but the effects of a snooze alarm on waking are unclear. We examined the effects of a snooze alarm on sleep inertia, which is a transitional state characterized by reduced arousal and impaired cognitive and behavioral performance immediately upon awakening. Methods: In study 1, healthy Japanese university students responded to a sleep survey during a psychology class (study 1), and we collected 293 valid responses. In study 2, we compared a separate sample of university students (n = 10) for the effects of using or not using a snooze alarm on sleep inertia immediately after awakening from normal nocturnal sleep in a sleep laboratory. Results: Of 293 valid respondents in study 1, 251 often used a tool to wake up in the morning (85.7%). Moreover, 70.5% reported often using the snooze function of their mobile phones, mainly to reduce anxiety about oversleeping. Study 2 indicated no differences in the sleep quality or quantity before awakening with or without the snooze alarm, except in the last 20 min. However, during the last 20 min of sleep with snooze alarm, the snooze alarm prolonged waking and stage N1 sleep. Stage N1 sleep is non-rapid eye movement sleep that is primarily defined as a drowsy state. Furthermore, Global Vigor values were enhanced after awakening compared to pre-sleep in the no-snooze condition. Conclusions: Using a snooze alarm prolongs sleep inertia compared to a single alarm, possibly because snooze alarms induce repeated forced awakenings.