Cognitive Performance, Sleepiness, and Mood in Partially Sleep Deprived Adolescents: The Need for Sleep Study

Sleep spindles in adolescence: a comparison across sleep restriction and sleep extension

BACKGROUND

The tendency for adolescents to have restricted sleep has been examined in numerous studies; however, the impact of sleep restriction on adolescents' neural activity during sleep (measured by electroencephalography (EEG)) is less extensively researched, particularly regarding sleep spindles.

METHODS

In this experimental study, 34 adolescents attended a 10-day laboratory study where they received five consecutive nights of either 5 h, 7.5 h or 10 h of sleep opportunity, with one adaptation, one baseline and two recovery nights of 10 h of sleep opportunity before and after the experimental phase.

RESULTS

Both within- and between-subjects effects were observed for fast sleep spindle characteristics of density, duration and amplitude. Overall, when experiencing severe sleep restriction, fast spindles in adolescents were lower in amplitude and longer in duration. Sex differences were also seen for fast spindle amplitude.

CONCLUSIONS

This investigation adds to the knowledge in this field by investigating specific sleep spindle characteristics in the context of experimentally manipulated sleep. Sleep restriction is highly prevalent among adolescents. These findings indicate that chronic sleep restriction has an impact on brain activity related to sleep spindles.

Addressing the Social Determinants of Health: A Call to Action for School Nurses

Social determinants of health (SDOH), the conditions in which children are born, grow, live, work or attend school, and age, impact child health and contribute to health disparities. School nurses must consider these factors as part of their clinical practice because they significantly and directly influence child well-being. We provide clinical guidance for addressing the SDOH when caring for children with three common health problems (obesity, insufficient sleep, and asthma). Given their unique role as school-based clinical experts, care coordinators, and student advocates, school nurses are well suited to serve as leaders in addressing SDOH.

SCHOOL START TIME AND PSYCHOLOGICAL HEALTH IN ADOLESCENTS

PURPOSE OF REVIEW

Later school start times are associated with a number of benefits for adolescents. The purpose of the current review is to summarize the literature regarding the effects of delaying school start times on adolescent psychological health.

RECENT FINDINGS

We identified eight observational studies that examined the relationship between schools' starting times and psychological outcomes. Of these, three were longitudinal studies that reported measures of adolescent mental health improved following a start time delay. Two cross-sectional studies showed that mental health scores were higher in schools with later compared to earlier start times. Three studies found no relationship between start time and mental health.

SUMMARY

In the majority of studies reviewed, later school start times were associated with greater adolescent psychological health. However, inherent design drawbacks in the studies prevent us from concluding that these associations are causal. There are a wide range of potential benefits, beyond mental health, that later high school start times offer. This encouraging, emergent literature on delayed start times has led many school districts to consider changes to their start times.

Frontal Underactivation During Working Memory Processing in Adults With Acute Partial Sleep Deprivation: A Near-Infrared Spectroscopy Study

Individuals with partial sleep deprivation may have working memory (WM) impairment, but the underlying neural mechanism of this phenomenon is relatively unknown. The present study examined neural processing during WM performance in individuals with and without partial sleep deprivation using near-infrared spectroscopy (NIRS). Forty college students (10 males) were equally split into Sufficient Sleep (SS) and Insufficient Sleep (IS) groups based on self-reports of previous night's sleep duration. Participants in the SS group obtained the recommended amounts of sleep according to various sleep organizations (i.e., >7.0 h), whereas those in the IS group obtained amounts of sleep no greater than the lower limit of the recommendation (i.e., ≤7.0 h). All participants underwent an n-back paradigm with a WM load (i.e., 3-back) and a control condition (i.e., 0-back) while their prefrontal hemodynamics were recorded by NIRS. The IS and SS groups performed the tasks comparably well. However, unlike the SS group, which exhibited bilateral frontal activation indicated by increased oxyhemoglobin concentration and decreased deoxyhemoglobin concentration during WM processing (i.e., 3-back > 0-back), the IS group did not exhibit such activation. In addition, levels of WM-related frontal activation, especially those on the left side, correlated with sleep duration the night before, even when habitual sleep duration was controlled for. The findings suggest the presence of frontal lobe dysfunction in the absence of evident WM difficulties in individuals with acute partial sleep deprivation. They also highlight the importance of a good night's sleep to brain health.

Regular Practice of Competitive Sports Does Not Impair Sleep in Adolescents: DADOS Study

PURPOSE

To analyze differences in sleep quality and duration by athletic status and sex, and to examine the association between physical activity (PA) recommendation and sleep in adolescents.

METHODS

A total of 267 adolescents [13.9 (0.3) y] from Deporte, ADOlescencia y Salud (DADOS) study (129 girls) were included in this cross-sectional analysis. Athletes competed regularly in organized sport events and trained ≥3 days per week, but nonathletes did not compete. PA was assessed by GENEActiv accelerometer. PA values were dichotomized into inactive (<60 min/d of moderate and vigorous PA) and active (≥60 min/d of moderate and vigorous PA). Sleep quality was evaluated with the Spanish version of the Pittsburgh Sleep Quality Index. Pittsburgh Sleep Quality Index values were dichotomized into >5 (poor quality) or ≤5 (good quality). Sleep duration was objectively measured by accelerometer.

RESULTS

Sleep quality and duration were not statistically different between athletes [median (Mdn) = 4.0, interquartile range (IQR) = 3.0-6.0 and Mdn = 8.0, IQR = 7.4-8.6 h, respectively] and nonathletes (Mdn = 5.0, IQR = 3.0-7.0 and Mdn = 7.9; IQR = 7.3-8.6 h, respectively), P > .05. Nonathlete or inactive adolescents did not show higher risk for poor sleep quality or short sleep duration than athletes [odds ratio (OR) = 1.17; 95% confidence interval (CI), 0.68-2.00 and OR = 0.93; 95% CI, 0.56-1.55, respectively] or active peers (OR = 1.39; 95% CI, 0.66-2.89 and OR = 1.62; 95% CI, 0.78-3.37, respectively).

CONCLUSIONS

In our group of adolescents, competitive sport practice did not alter sleep patterns. PA recommendations for adolescents may not discriminate between good and poor sleepers.

Dynamic functional connectivity and its behavioral correlates beyond vigilance

Fluctuations in resting-state functional connectivity and global signal have been found to correspond with vigilance fluctuations, but their associations with other behavioral measures are unclear. We evaluated 52 healthy adolescents after a week of adequate sleep followed by five nights of sleep restriction to unmask inter-individual differences in cognition and mood. Resting state scans obtained at baseline only, analyzed using sliding window analysis, consistently yielded two polar dynamic functional connectivity states (DCSs) corresponding to previously reported 'low arousal' and 'high arousal' states. We found that the relative temporal preponderance of two dynamic connectivity states (DCS) in well-rested participants, indexed by a median split of participants, based on the relative time spent in these DCS, revealed highly significant group differences in vigilance at baseline and its decline following multiple nights of sleep restriction. Group differences in processing speed and working memory following manipulation but not at baseline suggest utility of DCS in predicting cognitive vulnerabilities unmasked by a stressor like sleep restriction. DCS temporal predominance was uninformative about mood and sleepiness speaking to specificity in its behavioral predictions. Global signal fluctuation provided information confined to vigilance. This appears to be related to head motion, which increases during periods of low arousal.

Daytime microsleeps during 7 days of sleep restriction followed by 13 days of sleep recovery in healthy young adults

We investigated the consequences of sleep restriction (SR) on maintenance of wakefulness capacities and diurnal sleepiness through microsleeps monitoring. 12 healthy males (20-36 years old) were sleep restricted (4 h per night) during 7 nights followed by 13 nights of recovery sleep. Participants completed Karolinska Sleepiness Scale (KSS) and Maintenance of Wakefulness Test (MWT) at baseline (B), during SR (SR1, SR4 and SR7) and during recovery (R3 and R13), while continuously recorded for EEG analysis. During SR, MWT latencies decreased (SR7: -24.4%), whereas the number, the cumulative duration of microsleeps and KSS scores increased. Recovery nights allowed MWT latencies, KSS scores and all sleep values to return to baseline levels, while a rebound in N3, N3% and REM% sleep stages occurred. During SR, the maintenance of N3 sleep duration seems not sufficient to reduce daytime sleepiness and MWT results did not reflect the sleepiness levels characterized by persistent sleep attacks.

Can you snooze your way to an 'A'? Exploring the complex relationship between sleep, autonomic activity, wellbeing and performance in medical students

OBJECTIVE

Medical training brings with it multiple stressors, including demanding workloads in highly competitive environments, with well-documented impact on psychiatric morbidity. This study evaluated the impact of sleep-related factors on psychological wellbeing, cognitive task performance and academic standing in medical students.

METHODS

A total of 59 undergraduate medical students took part in this cross-sectional study over two consecutive days. Participants responded to questionnaires about their physical and psychological health, sleep, functioning and academic performance at the initial visit. Participants then wore an ambulatory bioharness overnight (to derive heart rate variability measures), before returning to complete a computerised battery of cognitive tasks. A sleep diary was completed for the next 7 days.

RESULTS

Poor sleep quality in the month preceding assessment correlated with psychological distress ( p < 0.001) and reduced nocturnal heart rate variability ( p = 0.007). Psychological distress also correlated with reduced nocturnal heart rate variability ( p = 0.031) and less refreshing sleep during the monitoring week ( p < 0.001), but not with sleep timing parameters. A greater increase in heart rate variability during the transition from awake to sleep significantly predicted better spontaneous cognitive performance ( p = 0.021). Better academic standing was predicted by consistently short, less refreshing sleep (all p < 0.001), along with earlier bedtimes ( p = 0.004) and greater psychological wellbeing ( p = 0.009).

CONCLUSION

Unrefreshing, short-duration sleep and psychological distress are prevalent in medical students during university training and were associated with reduced nocturnal parasympathetic autonomic activity. Achieving higher academic grades was associated with high psychological wellbeing despite consistently short, unrefreshing sleep. The long-term repercussions of such sleep behaviours on later professional functioning remain unclear, warranting further research.

Multiple nights of partial sleep deprivation do not affect prospective remembering at long delays

Prospective memory is defined as remembering to do something at a particular moment in the future and may be modulated by sleep. Here, we investigated whether multiple nights of partial sleep deprivation would affect the successful retrieval of intentions. Fifty-nine adolescents (mean age ± SD: 16.1 ± 0.6 years) were instructed to remember to press specific keys in response to the target words presented during a semantic categorization task in the future. Their memory was tested after five nights of either 5-h (sleep restriction group) or 9-h time-in-bed (control group). The average percentage of target words correctly responded to was small and did not significantly differ between the two groups (mean ± SEM for the sleep restriction group: 15.52 ± 6.61%; the control group: 23.33 ± 7.48%, p = 0.44). Thus, after the extended retention interval, prospective remembering was poor and did not appear to be affected by post-learning sleep restriction. These findings suggest a temporal boundary beyond which intentions fall below requisite levels of activation, potentially masking any benefits for retrieval conferred by sleep.

Neurobehavioral Impact of Successive Cycles of Sleep Restriction With and Without Naps in Adolescents

Study Objectives:

To characterize adolescents’ neurobehavioral changes during two cycles of restricted and recovery sleep and to examine the effectiveness of afternoon naps in ameliorating neurobehavioral deficits associated with multiple nights of sleep restriction.

Methods:

Fifty-seven healthy adolescents (aged 15–19 years; 31 males) participated in a parallel group study. They underwent two cycles of sleep restriction (5-hr time in bed [TIB] for five and three nights in the first and the second cycles, respectively; 01:00–06:00) and recovery (9-hr TIB for two nights per cycle; 23:00–08:00) intended to simulate the weekday sleep loss and weekend attempt to “catch up” on sleep. Half of the participants received a 1-hr nap opportunity at 14:00 following each sleep-restricted night, while the other half stayed awake. Sustained attention, sleepiness, speed of processing, executive function, and mood were assessed 3 times each day.

Results:

Participants who were not allowed to nap showed progressive decline in sustained attention that did not return to baseline after two nights of recovery sleep. Exposure to the second period of sleep restriction increased the rate of vigilance deterioration. Similar patterns were found for other neurobehavioral measures. Napping attenuated but did not eliminate performance decline. These findings contrasted with the stable performance of adolescents, given 9-hr TIB each night in our recent study.

Conclusions:

Adolescents’ neurobehavioral functions may not adapt to successive cycles of sleep curtailment and recovery. In sleep-restricted adolescents, weekend “catch-up sleep,” even when combined with napping during weekdays, is inferior to receiving a 9-hr sleep opportunity each night.

Impact of Multi-Night Experimentally Induced Short Sleep on Adolescent Performance in a Simulated Classroom

Study Objectives

Investigate whether a realistic "dose" of shortened sleep, relative to a well-rested state, causes a decline in adolescents' learning and an increase in inattentive and sleepy behaviors in a simulated classroom setting.

Methods

Eighty-seven healthy 14.0- to 16.9-year olds underwent a 3-week sleep manipulation protocol, including two 5-night sleep manipulation conditions presented in a randomly counterbalanced within-subjects cross-over design. Wake time was held constant. Bedtimes were set to induce Short Sleep (SS; 6.5 hours in bed) versus Healthy Sleep (HS; 10 hours in bed). During the morning at the end of each condition, participants underwent a simulated classroom procedure in which they viewed lecture-based educational videotapes and completed relevant quizzes. Their behaviors in the simulated classroom were later coded by condition-blind raters for evidence of inattention and sleepiness.

Results

Adolescents had a longer average sleep period during HS (9.1 hours) than SS (6.5 hours). Compared to scores during HS, adolescents scored significantly lower on the quiz, showed more behaviors suggestive of inattention and sleepiness in the simulated classroom, and were reported by adolescents themselves and by their parents to be more inattentive and sleepy during SS. However, the impact of the manipulation on quiz scores was not mediated by changes in attention or sleepiness.

Conclusions

Although effect sizes were modest, these findings suggest that previously-reported correlations between sleep duration and academic performance reflect true cause-effect relationships. Findings add to the growing evidence that the chronically shortened sleep experienced by many adolescents on school nights adversely impacts their functioning and health.

Novel Measures to Assess the Effects of Partial Sleep Deprivation on Sensory, Working, and Permanent Memory

Sleepiness has repeatedly been demonstrated to affect performance on a variety of cognitive tasks. While the effects of total sleep deprivation (TSD) have been extensively studied, acute partial sleep deprivation (PSD), a more frequent form of sleep loss, has been studied much less often. The present study examined the effects of sleep deprivation on novel tasks involving classic sensory, working, and permanent memory systems. While the tasks did implicate different memory systems, they shared a need for effortful, sustained attention to maintain successful performance. Because of the novelty of the tasks, an initial study of the effects of TSD was carried out. The effects of PSD were subsequently examined in a second study, in which subjects were permitted only 4 h of sleep. A general detrimental effect of both total and PSD on accuracy of detection was observed and to a lesser extent, a slowing of the speed of responding on the different tasks. This overall effect is best explained by the often-reported inability to sustain attention following sleep loss. Specific effects on distinct cognitive processes were also observed, and these were more apparent following total than PSD.

Non-REM sleep-disordered breathing affects performance on the psychomotor vigilance task

PURPOSE

Although many studies have investigated the clinical importance of sleep apnea on rapid eye movement (REM) and non-REM (NREM) sleep, the relationship between behavioral performance and apneic events during different sleep phases remains unclear. In the present study, we sought to investigate the effect of sleep phase fragmentation due to sleep-disordered breathing (SDB) during REM and NREM on the vigilance and sustainability of attention based on psychomotor vigilance task (PVT) performance.

METHODS

From a pool of subjects who underwent consecutive diagnostic polysomnography (PSG) for obstructive sleep apnea, 163 adult subjects with both REM and NREM sleep ≥ 30 min were enrolled for our study and performed a standardized 10-min PVT. The main outcome variables of the PVT were mean reaction time (RT), PVT Lapse count, and the slope of the reciprocal RT. Subjective sleepiness was measured using the Epworth Sleepiness Scale (ESS).

RESULTS

After multivariate linear regression analysis with adjustment for age, sex, body mass index, and the apnea-hypopnea index (AHI) of the counterpart sleep phase, we found that AHI during NREM (AHI_NREM) compared to AHI during REM (AHI_REM) was significantly associated with PVT lapses.

CONCLUSIONS

Our results suggest that SDB during NREM has a significant impact on vigilance lapses compared to that of REM.

Variable School Start Times and Middle School Student's Sleep Health and Academic Performance

PURPOSE

Improving sleep health among adolescents is a national health priority and implementing healthy school start times (SSTs) is an important strategy to achieve these goals. This study leveraged the differences in middle school SST in a large district to evaluate associations between SST, sleep health, and academic performance.

METHODS

This cross-sectional study draws data from a county-wide surveillance survey. Participants were three cohorts of eighth graders (n = 26,440). The school district is unique because SST ranged from 7:20 a.m. to 8:10 a.m. Path analysis and probit regression were used to analyze associations between SST and self-report measures of weekday sleep duration, grades, and homework controlling for demographic variables (sex, race, and socioeconomic status). The independent contributions of SST and sleep duration to academic performance were also analyzed.

RESULTS

Earlier SST was associated with decreased sleep duration (χ² = 173, p < .0001) and deficient sleep (≤7 hours) among 45% of students. Students with SST before 7:45 a.m. were at increased risk of decreased sleep duration, academic performance, and academic effort. Path analysis models demonstrated the independent contributions of sleep duration, SST, and variable effects for demographic variables.

CONCLUSIONS

This is the first study to evaluate the independent contributions of SST and sleep to academic performance in a large sample of middle school students. Deficient sleep was prevalent, and the earliest SST was associated with decrements in sleep and academics. These findings support the prioritization of policy initiatives to implement healthy SST for younger adolescents and highlight the importance of sleep health education disparities among race and gender groups.

Effects of Sleep Deprivation on the Cognitive Performance of Nurses Working in Shift

INTRODUCTION

Sleep deprivation and altered circadian rhythm affects the cognitive performance of an individual. Quality of sleep is compromised in those who are frequently involved in extended working hours and shift work which is found to be more common among nurses. Cognitive impairment leads to fatigability, decline in attention and efficiency in their workplace which puts their health and patients' health at risk.

AIM

To find out the prevalence of sleep deprivation and its impact on cognition among shift working nurses.

MATERIALS AND METHODS

Sleep deprivation among 97 female and three male healthy nurses of age 20-50 years was assessed by Epworth sleepiness scale (ESS). Cognition was assessed by Montreal Cognitive Assessment (MoCA) questionnaire. Mobile applications were used to test their vigilance, reaction time, photographic memory and numerical cognition. The above said parameters were assessed during end of day shift and 3-4 days after start of night shift.

RESULTS

Poor sleep quality was observed among 69% of shift working nurses according to ESS scores. The cognitive performance was analysed using Wilcoxon signed rank test. The MoCA score was found to be lesser among 66% of nurses during night (25.72) than day (26.81). During the night, 32% made more mathematical errors. It was also found that, 71%, 83% and 68% of the nurses scored lesser during night in the Stroop's colour test, vigilance test and memory tests respectively. Thus, impairment in cognitive performance was statistically significant (p<0.001) among shift working nurses.

CONCLUSION

Cognitive performance was found to be impaired among shift working nurses, due to poor sleep quality and decreased alertness during wake state. Thus, shift work poses significant cognitive risks in work performance of nurses.

Memory encoding is impaired after multiple nights of partial sleep restriction

Sleep is important for normative cognitive functioning. A single night of total sleep deprivation can reduce the capacity to encode new memories. However, it is unclear how sleep restriction during several consecutive nights affects memory encoding. To explore this, we employed a parallel-group design with 59 adolescents randomized into sleep-restricted (SR) and control groups. Both groups were afforded 9 h time in bed (TIB) for 2 baseline nights, followed by 5 consecutive nights of 5 h TIB for the SR group (n = 29) and 9 h TIB for the control group (n = 30). Participants then performed a picture-encoding task. Encoding ability was measured with a recognition test after 3 nights of 9 h TIB recovery sleep for both groups, allowing the assessment of encoding ability without the confounding effects of fatigue at retrieval. Memory was significantly worse in the sleep-restricted group (P = 0.001), and this impairment was not correlated with decline in vigilance. We conclude that memory-encoding deteriorates after several nights of partial sleep restriction, and this typical pattern of sleep negatively affects adolescents' ability to learn declarative information.

Poor habitual sleep efficiency is associated with increased cardiovascular and cortisol stress reactivity in men

Inadequate sleep and psychological stress can both elevate physiological stress markers, such as cortisol. Prior studies that have applied induced psychosocial stress after a night of experimental sleep deprivation have found these effects to be compounded. We examined whether the relationship between stress reactivity and poor sleep also extends to habitual sleep patterns. Fifty-nine adult male participants were recruited. Habitual sleep patterns were monitored with actigraphy for a week. Participants subsequently underwent the Trier Social Stress Test. Cardiovascular responses and salivary cortisol were measured at baseline, during stress, and during recovery. Subjects who showed poor habitual sleep efficiency during the week before stress induction responded with higher stress-related elevations of blood pressure and cortisol levels as compared to subjects with high sleep efficiency. This relationship between poor sleep efficiency and elevated blood pressure persisted during the post-stress recovery period. Similar associations between total sleep time in the week prior to the stress induction and physiological reactivity did not reach significance. Our findings indicate that habitual low sleep efficiency exaggerates cardiovascular and neuroendocrine effects of psychosocial stress, in a male population.

Sleepiness in Adolescents

Sleepiness and sleep deprivation among adolescents are increasingly being recognized as a public health concern. Many of the determinants of this growing problem lie beyond the biomedical scope of explanation. In this article, the authors begin with a review of the prevalence and consequences of sleepiness in adolescents and then present the approach to a sleepy adolescent and the underlying cause. The topic is discussed from clinical as well as public health perspectives.

School-Based Sleep Education Programs for Short Sleep Duration in Adolescents: A Systematic Review and Meta-Analysis

BACKGROUND

Insufficient sleep among students is a major school health problem. School-based sleep education programs tailored to reach large number of students may be one of the solutions. A systematic review and meta-analysis was conducted to summarize the programs' effectiveness and current status.

METHODS

Electronic databases were searched up until May 2015. Randomized controlled trials of school-based sleep intervention among 10- to 19-year-old students with outcome on total sleep duration were included. Methodological quality of the studies was assessed using the Cochrane's risk of bias assessment.

RESULTS

Seven studies were included, involving 1876 students receiving sleep education programs and 2483 attending classes-as-usual. Four weekly 50-minute sleep education classes were most commonly provided. Methodological quality was only moderate, with a high or an uncertain risk of bias in several domains. Compared to classes-as-usual, sleep education programs produced significantly longer weekday and weekend total sleep time and better mood among students at immediate post-treatment, but the improvements were not maintained at follow-up.

CONCLUSIONS

Limited by the small number of studies and methodological limitations, the preliminary data showed that school-based sleep education programs produced short-term benefits. Future studies should explore integrating sleep education with delayed school start time or other more effective approaches.

Neural Consequences of Chronic Short Sleep: Reversible or Lasting?

Approximately one-third of adolescents and adults in developed countries regularly experience insufficient sleep across the school and/or work week interspersed with weekend catch up sleep. This common practice of weekend recovery sleep reduces subjective sleepiness, yet recent studies demonstrate that one weekend of recovery sleep may not be sufficient in all persons to fully reverse all neurobehavioral impairments observed with chronic sleep loss, particularly vigilance. Moreover, recent studies in animal models demonstrate persistent injury to and loss of specific neuron types in response to chronic short sleep (CSS) with lasting effects on sleep/wake patterns. Here, we provide a comprehensive review of the effects of chronic sleep disruption on neurobehavioral performance and injury to neurons, astrocytes, microglia, and oligodendrocytes and discuss what is known and what is not yet established for reversibility of neural injury. Recent neurobehavioral findings in humans are integrated with animal model research examining long-term consequences of sleep loss on neurobehavioral performance, brain development, neurogenesis, neurodegeneration, and connectivity. While it is now clear that recovery of vigilance following short sleep requires longer than one weekend, less is known of the impact of CSS on cognitive function, mood, and brain health long term. From work performed in animal models, CSS in the young adult and short-term sleep loss in critical developmental windows can have lasting detrimental effects on neurobehavioral performance.

Impact of social media usage on daytime sleepiness: A study in a sample of tertiary students in Singapore

Objective

Many tertiary students access social networking sites on a daily basis. With the increased usage of smartphones, accessing social networking sites while commuting, in schools, waiting for friends, television commercial breaks has become prevalent among tertiary students. What started as a lifestyle choice has now become a daily necessity. Such behavior among tertiary students raises an important question for educators: how does social media usage affect tertiary students’ sleep patterns and daytime sleepiness, their attention difficulties, especially in school? Thus, the aim of this study was to examine the relationships between tertiary students' self-reports of social media usage and daytime sleepiness.

Design

The design was a cross-sectional, quantitative research study.

Methods

We used a survey that contained questions concerning demographic data, daytime sleepiness, total sleep time and social media usage and a version of the Cleveland Adolescent Sleepiness Questionnaire, modified for use in tertiary students, were used for data collection (n = 969).

Results

The most preferred tool for accessing social networking sites was smartphones and WhatsApp was the most accessed site. Results indicated that nocturnal technology use has a weak, negative impact on tertiary students’ quantity of sleep that may lead to daytime sleepiness. Local Singapore students spent significantly more time on social networking sites at night compared to foreign students. As a result, local students experienced more daytime sleepiness compared to foreign students.

Conclusions

Prolonged social media usage, especially in bed, has a negative impact on tertiary students’ daytime sleepiness. Since the technology is such an integral part of most tertiary students’ lives, it is important to understand the impact it has on their sleep and daytime sleepiness.

Consensus Statement of the American Academy of Sleep Medicine on the Recommended Amount of Sleep for Healthy Children: Methodology and Discussion

ABSTRACT

Members of the American Academy of Sleep Medicine developed consensus recommendations for the amount of sleep needed to promote optimal health in children and adolescents using a modified RAND Appropriateness Method. After review of 864 published articles, the following sleep durations are recommended: Infants 4 months to 12 months should sleep 12 to 16 hours per 24 hours (including naps) on a regular basis to promote optimal health. Children 1 to 2 years of age should sleep 11 to 14 hours per 24 hours (including naps) on a regular basis to promote optimal health. Children 3 to 5 years of age should sleep 10 to 13 hours per 24 hours (including naps) on a regular basis to promote optimal health. Children 6 to 12 years of age should sleep 9 to 12 hours per 24 hours on a regular basis to promote optimal health. Teenagers 13 to 18 years of age should sleep 8 to 10 hours per 24 hours on a regular basis to promote optimal health. Sleeping the number of recommended hours on a regular basis is associated with better health outcomes including: improved attention, behavior, learning, memory, emotional regulation, quality of life, and mental and physical health. Regularly sleeping fewer than the number of recommended hours is associated with attention, behavior, and learning problems. Insufficient sleep also increases the risk of accidents, injuries, hypertension, obesity, diabetes, and depression. Insufficient sleep in teenagers is associated with increased risk of self-harm, suicidal thoughts, and suicide attempts.

COMMENTARY

A commentary on this article apears in this issue on page 1439.

Long work hours and chronic insomnia are associated with needlestick and sharps injuries among hospital nurses in Taiwan: A national survey

BACKGROUND

Needlestick and sharps injuries are prevalent work-related injuries among nurses. Safety devices prevent only one-quarter of related injuries. More studies of modifiable risk factors are needed.

OBJECTIVES

To examine whether long work hours and chronic insomnia are associated with needlestick and sharps injuries among hospital nurses in Taiwan.

DESIGN

Cross-sectional survey.

SETTINGS/PARTICIPANTS

This analysis included 19,386 full-time bedside nurses working in 104 hospitals across Taiwan.

METHODS

Participants filled out an anonymous questionnaire from July to September 2014. Chronic insomnia, needlestick injuries, and sharps injuries during the past year were each measured by a yes/no question. Multivariate logistic regression models were applied to examine the effects of long work hours and chronic insomnia on needlestick and sharps injuries, given with control for sex, marital status, educational level, age, years of practice, work unit, and hospital level in the model.

RESULTS

More than 70% of study nurses worked long hours during the previous week (>50h: 27.5%; 41-50h: 43.2%), and 15.5% of nurses reported chronic insomnia. The percentage of sharps injuries (38.8%) was higher than that for needlestick injuries (22.4%) during the previous year among nurses. After adjusting for potential confounders, logistic regression yielded significant results showing that those who worked 41 to 50h per week, >50h per week, and had chronic insomnia were 1.17 times (95% C.I.=1.04-1.32), 1.51 times (95% C.I.=1.32-1.72), and 1.45 times (95% C.I.=1.25-1.68) more likely to experience needlestick injuries, and 1.29 times (95% C.I.=1.17-1.42), 1.37 times (95% C.I.=1.23-1.53), and 1.56 times (95% C.I.=1.37-1.77) more likely to experience sharps injuries, respectively, than those who worked fewer hours and did not have insomnia.

CONCLUSIONS

This nationwide nurse survey showed that high rates of needlestick and sharps injuries persist in hospital nurses in Taiwan. The common problems of long work hours and chronic insomnia increase the risk of these injuries. We suggest that hospital managers follow regulations on work hours and optimize shift schedules for nurses to decrease related injuries.

Sleep Restriction Impairs Vocabulary Learning when Adolescents Cram for Exams: The Need for Sleep Study

STUDY OBJECTIVES

The ability to recall facts is improved when learning takes place at spaced intervals, or when sleep follows shortly after learning. However, many students cram for exams and trade sleep for other activities. The aim of this study was to examine the interaction of study spacing and time in bed (TIB) for sleep on vocabulary learning in adolescents.

METHODS

In the Need for Sleep Study, which used a parallel-group design, 56 adolescents aged 15-19 years were randomly assigned to a week of either 5 h or 9 h of TIB for sleep each night as part of a 14-day protocol conducted at a boarding school. During the sleep manipulation period, participants studied 40 Graduate Record Examination (GRE)-type English words using digital flashcards. Word pairs were presented over 4 consecutive days (spaced items), or all at once during single study sessions (massed items), with total study time kept constant across conditions. Recall performance was examined 0 h, 24 h, and 120 h after all items were studied.

RESULTS

For all retention intervals examined, recall of massed items was impaired by a greater amount in adolescents exposed to sleep restriction. In contrast, cued recall performance on spaced items was similar between sleep groups.

CONCLUSIONS

Spaced learning conferred strong protection against the effects of sleep restriction on recall performance, whereas students who had insufficient sleep were more likely to forget items studied over short time intervals. These findings in adolescents demonstrate the importance of combining good study habits and good sleep habits to optimize learning outcomes.

Chronic sleep deprivation differentially affects short and long-term operant memory in Aplysia

The induction, formation and maintenance of memory represent dynamic processes modulated by multiple factors including the circadian clock and sleep. Chronic sleep restriction has become common in modern society due to occupational and social demands. Given the impact of cognitive impairments associated with sleep deprivation, there is a vital need for a simple animal model in which to study the interactions between chronic sleep deprivation and memory. We used the marine mollusk Aplysia californica, with its simple nervous system, nocturnal sleep pattern and well-characterized learning paradigms, to assess the effects of two chronic sleep restriction paradigms on short-term (STM) and long-term (LTM) associative memory. The effects of sleep deprivation on memory were evaluated using the operant learning paradigm, learning that food is inedible, in which the animal associates a specific netted seaweed with failed swallowing attempts. We found that two nights of 6h sleep deprivation occurring during the first or last half of the night inhibited both STM and LTM. Moreover, the impairment in STM persisted for more than 24h. A milder, prolonged sleep deprivation paradigm consisting of 3 consecutive nights of 4h sleep deprivation also blocked STM, but had no effect on LTM. These experiments highlight differences in the sensitivity of STM and LTM to chronic sleep deprivation. Moreover, these results establish Aplysia as a valid model for studying the interactions between chronic sleep deprivation and associative memory paving the way for future studies delineating the mechanisms through which sleep restriction affects memory formation.

Sleep deprivation increases formation of false memory

Retrieving false information can have serious consequences. Sleep is important for memory, but voluntary sleep curtailment is becoming more rampant. Here, the misinformation paradigm was used to investigate false memory formation after 1 night of total sleep deprivation in healthy young adults (N = 58, mean age ± SD = 22.10 ± 1.60 years; 29 males), and 7 nights of partial sleep deprivation (5 h sleep opportunity) in these young adults and healthy adolescents (N = 54, mean age ± SD = 16.67 ± 1.03 years; 25 males). In both age groups, sleep-deprived individuals were more likely than well-rested persons to incorporate misleading post-event information into their responses during memory retrieval (P < 0.050). These findings reiterate the importance of adequate sleep in optimal cognitive functioning, reveal the vulnerability of adolescents' memory during sleep curtailment, and suggest the need to assess eyewitnesses' sleep history after encountering misleading information.

The Effects of Sleep Problems on the Trajectory of Antisocial Behavior from Adolescence through Early Adulthood in Taiwan: Family Functioning as a Moderator

STUDY OBJECTIVES

To examine the longitudinal relationship between sleep problems and development of antisocial behavior from adolescence through young adulthood, and to investigate whether family functioning moderates the association being examined. Potential sex differences were also explored.

METHODS

A total of 2,491 adolescents participated in a prospective study spanning 2009 through 2014 in northern Taiwan. Measures included sleep problems, family functioning (parental support, family interaction, and family conflict), antisocial behavior, and other individual characteristics (sex, age, parental education, family economic stress, depressive symptoms, and stressful life events). Random coefficient growth models were used to test study hypotheses.

RESULTS

Sleep problems were significantly and positively associated with antisocial behavior (B = 0.088 and 0.038 for males and females, respectively). Sex differences further emerged in the moderating effects of family functioning. Among males, those with high family interaction had a weaker association between sleep problems and antisocial behavior; among females, the examined association was weaker in those with high parental support. For both sexes, the association between sleep problems and antisocial behavior was stronger for those with high family conflict.

CONCLUSIONS

Our findings highlight the robust link between sleep problems and adolescent antisocial behavior over time. We also show for the first time that the association depends on family functioning. Prevention methods and treatment of sleep problems in youths that incorporate family functioning may yield significant benefits for decreasing antisocial behavior. Sex-specific intervention and prevention approaches should also be considered.

Sleep restriction can attenuate prioritization benefits on declarative memory consolidation

As chronic sleep restriction is a widespread problem among adolescents, the present study investigated the effects of a 1-week sleep restriction (SR) versus control period on the consolidation of long-term memory for prose passages. We also determined whether the benefit of prioritization on memory is modulated by adequate sleep occurring during consolidation. Fifty-six healthy adolescents (25 male, aged 15-19 years) were instructed to remember a prose passage in which half of the content was highlighted (prioritized), and were told that they would receive an additional bonus for remembering highlighted content. Following an initial free recall test, participants underwent a 7-night period in which they received either a 5-h (SR) or 9-h (control) nightly sleep opportunity, monitored by polysomnography on selected nights. Free recall of the passage was tested at the end of the sleep manipulation period (1 week after encoding), and again 6 weeks after encoding. Recall of highlighted content was superior to that of non-highlighted content at all three time-points (initial, 1 week, 6 weeks). This beneficial effect of prioritization on memory was stronger 1 week relative to a few minutes after encoding for the control, but not the SR group. N3 duration was similar in the control and SR groups. Overall, the present study shows that the benefits of prioritization on memory are enhanced over time, requiring time and sleep to unfold fully. Partial sleep deprivation (i.e. 5-h nocturnal sleep opportunity) may attenuate such benefits, but this may be offset by preservation of N3 sleep duration.

EEG Changes across Multiple Nights of Sleep Restriction and Recovery in Adolescents: The Need for Sleep Study

STUDY OBJECTIVES

To investigate sleep EEG changes in adolescents across 7 nights of sleep restriction to 5 h time in bed [TIB]) and 3 recovery nights of 9 h TIB.

METHODS

A parallel-group design, quasi-laboratory study was conducted in a boarding school. Fifty-five healthy adolescents (25 males, age = 15-19 y) who reported habitual TIBs of approximately 6 h on week nights (group average) but extended their sleep on weekends were randomly assigned to Sleep Restriction (SR) or Control groups. Participants underwent a 2-week protocol comprising 3 baseline nights (TIB = 9 h), 7 nights of sleep opportunity manipulation (TIB = 5 h for the SR and 9 h for the Control group), and 3 nights of recovery sleep (TIB = 9 h). Polysomnography was obtained on two baseline, three manipulation, and two recovery nights.

RESULTS

Across the sleep restriction nights, total SWS duration was preserved relative to the 9 h baseline sleep opportunity, while other sleep stages were reduced. Considering only the first 5 h of sleep opportunity, SR participants had reduced N1 duration and wake after sleep onset (WASO), and increased total sleep time (TST), rapid eye movement (REM) sleep, and slow wave sleep (SWS) relative to baseline. Total REM sleep, N2, and TST duration remained above baseline levels by the third recovery sleep episode.

CONCLUSIONS

In spite of preservation of SWS duration over multiple nights of sleep restriction, adolescents accustomed to curtailing nocturnal sleep on school day nights evidence residual effects on sleep macro-structure, even after three nights of recovery sleep. Older teenagers may not be as resilient to successive nights of sleep restriction as is commonly believed.