The protective effect of daytime sleep on planning and risk-related decision-making in emerging adults

Benefits of napping habits in healthy adults: Maintaining alerting performance and cortisol levels change within 90 min of habitual napping time

BACKGROUND

Napping is garnering increased attention as a strategy for adults to sustain alertness and alleviate stress in contemporary society. The nuances of napping habits are emerging as an independent factor influencing the extent of individual benefits. This study aimed to demonstrate the long-term benefits of napping and explore the impact of napping habits on individual alertness, as well as whether this effect was correlated with cortisol levels.

METHODS

The study involved 80 healthy adults categorized into two groups based on self-reported napping habits: habitual nappers (n = 49) and non-habitual nappers (n = 31). Karolinska Sleepiness Scale (KSS), psychomotor vigilance task (PVT), and saliva collection were performed every 30 min within 90 min in the absence of napping during the afternoon dip. The measurements were analyzed using repeated measures ANOVA and Pearson correlation analyses.

RESULTS

There was an interaction between groups and time in reaction speed and lapse number of PVT and cortisol (all p < 0.05). Post hoc analysis found that habitual nappers maintained higher objective alertness and experienced more significant increases in cortisol over time (all p < 0.05). The cortisol levels at sleepiness time were negatively associated with the slowest 10 % reaction speed of PVT in non-habitual nappers (r = -0.409, p = 0.022).

CONCLUSION

Under the premise of mitigating the impacts of acute nap deprivation on sleep homeostasis and rhythm, napping habits emerge as a potential factor influencing the ability of individuals to sustain heightened alertness.

Sleep and Socioemotional Outcomes Among Sexual and Gender Minority Adolescents: A Longitudinal Study

Sexual and gender minority adolescents face specific stressors associated with their minority status, leading to compromised socioemotional outcomes and sleep. Sleep patterns have, in turn, been found to predict socioemotional outcomes. As such, we aimed to investigate whether healthy sleep patterns prospectively predicted socioemotional outcomes, and whether associations varied as a function of sexual and gender minority status. We conducted a secondary data analysis among adolescents at age 14 to 17, from a nationally representative prospective cohort in the United Kingdom (N = 8923, mean age = 13.8), with 7021 cisgender heterosexual, 1801 sexual minority, and 101 gender minority adolescents. Indicators of socioemotional outcomes included self-esteem, emotional well-being, peer relationships, and relationship with parents. The results showed that gender minority adolescents reported the worst sleep patterns and socioemotional outcomes, followed by sexual minority and cisgender heterosexual adolescents. Results from multi-group path analyses showed that emotional well-being, self-esteem, and peer relationships at age 17 were prospectively predicted by sleep patterns and the associations were moderated by sexual and gender minority status. Influence of sleep patterns, particularly sleep initiation problems and frequent awakening, on socioemotional outcomes was greater among gender minority adolescents, when compared to cisgender heterosexual adolescents. In conclusion, positive socioemotional outcomes were predicted by healthy sleep patterns. The potential role of sleep health in optimizing socioemotional outcomes among sexual and gender minority adolescents might warrant further investigation in prevention or intervention studies.

Daytime Napping Benefits Passing Performance and Scanning Activity in Elite Soccer Players

The present study explored the effect of a daytime napping opportunity on scanning activity, which is an essential component of successful soccer performance. Fourteen male elite collegiate soccer players performed the Trail Making Test (TMT), which was used to assess complex visual attention. In addition, a soccer passing test, modified with reference to the Loughborough Soccer Passing Test, was used to evaluate passing performance as well as scanning activity. A cross-over design was applied to examine nap and no-nap interventions. Participants (N = 14, mean age: 21.6 SD = 0.5 years, height: 1.73 ± 0.06 m, body mass: 67.1 ± 4.5 kg) were randomly allocated to a midday nap (40 minutes) or no-nap group. Subjective sleepiness was measured using the Karolinska Sleepiness Scale, and perceptive fatigue was evaluated by the visual analog scale. There were no significant differences in subjective measurements or TMT between the nap and no-nap groups. However, the performance time for the passing test and scanning activity was significantly shorter (p < 0.001) and scanning activity was significantly more frequent in the nap condition than in the no-nap condition (p < 0.00005). These results suggest that daytime napping is beneficial for soccer-related cognitive function, represented by visuospatial processing and decision-making, and particularly as a potential countermeasure to mental fatigue. Considering that inadequate sleep and residual fatigue are commonly observed in elite soccer, this finding may have practical implications for the preparation of players.

Planning Ability and Alertness After Nap Deprivation: Beneficial Effects of Acute Moderate-Intensity Aerobic Exercise Greater Than Sitting Naps

Nap deprivation is regarded as a sleep loss for habitual nappers. The beneficial effects of napping and moderate-intensity aerobic exercise on the reduction in planning ability following nighttime sleep deprivation have been proven. However, it is still unknown whether it can improve the performance decline caused by daytime nap deprivation in habitual nappers. Seventy-four healthy adults who had a long-term habit of taking naps were assigned to three interventions after receiving nap deprivation: (1) Control group (no intervention); (2) Nap group (15-min sitting naps); (3) Exercise group (15-min aerobic exercise), in which subjective alertness, mood, fatigue, and task performance in objective alertness (Psychomotor Vigilance Task, PVT) and planning ability (the Tower of London Task) were measured. Results showed that nap deprivation negatively influenced some performance on the psychomotor vigilance (i.e., response times and 10% slowest response time) and planning ability (i.e., planning time). And acute moderate-intensity aerobic exercise improved psychomotor alertness (i.e., response times) and planning ability (i.e., execution accuracy, execution time), a 15-min sitting naps only alleviated subjective fatigue, whereas some performance (i.e., response times) deteriorated when no intervention was used. These findings suggested that acute moderate-intensity aerobic exercise has a better restorative effect on the reduced planning ability and objective alertness due to nap deprivation compared to sitting naps.

Sleep and Inhibitory Control Over Mood-Congruent Information in Emerging Adults With Depressive Disorder

OBJECTIVE

Accumulating evidence has suggested bidirectionality between sleep problems and depression, but the underlying mechanism is unclear. We assessed the role of sleep in inhibitory control ability with emotional stimuli, which has been shown to be suboptimal among individuals with depression and proposed to perpetuate depressive symptoms.

METHODS

Emerging adults (aged 18-25 years, 64.6% female) were screened for depressive and other mental disorders by structured clinical interview and questionnaire. Individuals with depressive disorders were assigned to have a polysomnography-monitored daytime sleep opportunity (Sleep-Dep, n = 20), whereas nondepressed individuals were randomized to either have daytime sleep (Sleep-Ctrl, n = 27) or stay awake (Wake-Ctrl, n = 18). Participants completed the Affective Go/No-Go Task two times, separated by experimental conditions.

RESULTS

A factorial model with a between-subject factor (Sleep-Dep/Sleep-Ctrl/Wake-Ctrl) and a within-subject factor (test 1/test 2) was used to assess if the groups differed in inhibitory control across test sessions, as inferred by changes in d-prime and false alarm rates (FA). Results from mixed factorial models showed a significant interaction effect between time and group on FA in the block with neutral faces as the target and happy faces as the nontarget (F(2,61) = 5.15, pfdr = .045). Although Sleep-Dep had decreased FA after sleep (t(19) = 2.94, pfdr = .050), Sleep-Ctrl and Wake-Ctrl had no significant between-session changes (p values > .05). Postsleep improvement in FA in Sleep-Dep correlated with longer stage 2 sleep (r(20) = 0.788, pfdr < .001) and stage 2 fast spindle number at O1 (r(18) = 0.692, pfdr = .015).

CONCLUSIONS

Sleep gain, particularly stage 2 sleep and related physiology, potentially enhances inhibitory control ability responding to emotional information among individuals with depressive disorders.