The short and long of adolescent sleep: the unique impact of day length

Study objectivesVariation in day length is proposed to impact sleep, yet it is unknown whether this is above the influence of behavioural factors. Day length, sleep hygiene, and parent-set bedtime were simultaneously explored, to investigate the relative importance of each on adolescents’ sleep.MethodsAn online survey was distributed in four countries at varying latitudes/longitudes (Australia, The Netherlands, Canada, Norway).ResultsOverall, 711 (242 male; age M = 15.7 ± 1.6, range = 12–19 yrs) adolescents contributed data. Hierarchical regression analyses showed good sleep hygiene was associated with earlier bedtime, shorter sleep latency, and longer sleep (β = −0.34; −0.30; 0.32, p < 0.05, respectively). Shorter day length predicted later bedtime (β = 0.11, p = 0.009), decreased sleep latency (β = −0.21, p < 0.001), and total sleep (β = −0.14, p = 0.001). Longer day length predicted earlier bedtimes (β = −0.11, p = 0.004), and longer sleep (β = 0.10, p = 0.011).ConclusionsSleep hygiene had the most clinical relevance for improving sleep, thus should be considered when implementing adolescent sleep interventions, particularly as small negative effects of shorter day length may be minimised through sleep hygiene techniques.     

Effects of sleep duration and weekend catch-up sleep on falling injury in adolescents: a population-based study

ObjectiveThis population-based study aimed to determine the effects of sleep deprivation and compensatory weekend catch-up sleep on the risk of falls in adolescents.MethodsData from the 2013 Korean Youth Risk Behavior Web-based Survey on 57,225 adolescents were investigated. Demographic, socioeconomic, sleep-related, health-related behavioral, and psychological variables were compared between fallers (n = 7346) and non-fallers (n = 49,879). Multivariate logistic regression analysis using a hierarchical model was carried out to identify sleep-related factors (eg, sleep duration, longer weekend catch-up sleep) independently contributing to the risk of falls.ResultsCompared to non-fallers, fallers were associated with a shorter sleep duration (p = 0.001) and later bedtimes on weekdays and weekends (p < 0.001). An average sleep duration of ≤ 5 h (odds ratio [OR] 1.23, 95% confidence interval [CI] 1.12–1.34) and of 6 h (OR 1.12, CI 1.03–1.21) were associated with an increased risk of falls. By contrast, an average sleep duration of ≥ 9 h (OR 0.90, CI: 0.82–0.99) and longer weekend catch-up sleep (OR 0.94, CI: 0.89–0.99) were associated with a decreased risk of falls.ConclusionOur results corroborate previous suggestions that short sleep duration is a major risk factor for falls among adolescents. Moreover, our study provided a novel finding that longer sleep duration and longer weekend catch-up sleep may have a protective effect against falls. Our findings have important public health implications that modifying school schedules to increase sleep duration could reduce unintentional falls and injuries in school-aged adolescents.     

Comparison of longitudinal diary and actigraphy-assessed sleep in pregnant women

Study objectivesVarious methods are employed to assess sleep in pregnant women, including self-report, sleep diary, and actigraphy. Unfortunately, the data are often contradictory, and interpretations are often inconsistent. The current aims are to compare subjective and objective sleep data in pregnant women collected longitudinally in early pregnancy.MethodsIn this secondary analysis of 104 pregnant women, sleep was collected via diary and actigraphy for 14 days during three separate occasions (10–12 weeks; 14–16 weeks; and 18–20 weeks). Sleep variables included wake after sleep onset (WASO), sleep efficiency (SE), bedtime/lights out, sleep onset latency (SL), and total sleep duration (TST). Repeated measures ANOVAs compared each sleep variable across Time and by Method of data collection, while controlling for parity and daytime naps.ResultsSignificant differences were noted for only the method of data collection for sleep component studied for WASO, F (1, 98) = 147.20, p < 0.001; SE, F (1, 98) = 129.41, p < 0.001); bedtime/lights out, F (1, 103) = 5.33, p < 0.05); and sleep duration, F (1, 104) = 182.75, p < 0.001). Significant variation was not seen in any variable across time-period. Conclusions: There are substantial discrepancies between diary- and actigraphy-assessed sleep measures in pregnant women which is in alignment with previous literature. These data highlight that these methodologies assess different constructs. We contend that these data may be useful as a reference to compare high-risk women or those with sleep disorders. Using a multi-modal approach to identify sleep disturbance in pregnancy is likely a more clinically useful option.     

Sleep duration and daytime sleepiness in a large sample of Brazilian high school adolescents

ObjectiveTo investigate the prevalence and main factors associated with short and long sleep duration and excessive daytime sleepiness in Brazilian adolescents.MethodsThis was a cross-sectional study of 11.525 students of both genders, aged 14–17 years, from the public high-school system. Sleep duration was assessed by self-report and <8 h of sleep per day was considered short sleep and >10 h, long sleep. Socio-demographic and behavioral factors were investigated through a purpose-built questionnaire and daytime somnolence was assessed by the Epworth sleepiness scale (ESS).ResultsThe overall prevalence of short and long sleep was 54.7% and 3.3%, respectively. Frequency of short sleep was lowest in the afternoon shift (38.2%) and highest in the morning shift (62.9%) and full-day students (70.0%). Insufficient sleep was more frequent in working (63.0%) than non-working adolescents (53.1%; p = 0.001) and among those who used their cell phone before bedtime (56.3%) compared to non-users (49.7%, p = 0.001). On average, ESS score was higher in subjects with short and long sleep (respectively, 9.7 ± 4.4 and 10.0 ± 4.5) compared to those with normal sleep duration (8.9 ± 4.2; p = 0.001).ConclusionInsufficient sleep and excessive daytime sleepiness are very common among urban high-school Brazilian adolescents. Full day and morning school shifts are associated with short sleep and daytime somnolence, suggesting later start times may have a role in reducing sleep loss in these subjects. Older age, work activity, and cell phone use before bedtime, are also risk factors for of short sleep in adolescents. Although less common, long sleep can also be associated with excessive daytime sleepiness.     

Quantitative association between nocturnal voiding frequency and objective sleep quality in the general elderly population: the HEIJO-KYO cohort

ObjectiveA significant association between nocturia and subjective sleep quality has previously been reported; however, the association between nocturia and objective sleep quality remains unclear. The purpose of this study was to evaluate the quantitative association between nocturnal voiding (NV) frequency and objective sleep quality in a large, general, elderly population.MethodsNocturnal voiding frequency, objective sleep quality, and subjective sleep quality were measured among 1086 community-based elderly individuals using actigraphy and the Pittsburgh Sleep Quality Index (PSQI) questionnaire.ResultsIn multivariate analyses adjusted for potential confounding factors (such as age, gender, body mass index, medication use, renal function, bedtime, rising time, daytime physical activity, endogenous melatonin levels, and bedroom light levels), increased NV frequency, ranging from zero, one, two, three or more voids, was significantly associated with poorer objective sleep quality, including lower sleep efficiency (SE) and longer wake after sleep onset (WASO) (mean SE, 86.3, 84.8, 83.6, and 81.2%, respectively; p for trend <0.001; mean WASO: 42.6, 49.0, 53.6, and 66.1 min, respectively; p for trend <0.001), but shorter sleep onset latency (SOL) (mean SOL, 3.0, 3.0, 2.8, and 2.8 log min, respectively; p for trend = 0.018). In addition, an increased NV frequency was significantly associated with poorer subjective sleep quality in a multivariate model (mean PSQI global score, 4.60, 4.86, 5.22, and 5.48, respectively; p for trend 0.012).ConclusionThe present study revealed a quantitative association between NV frequency and objective sleep quality in the general elderly population.     

Time for bed! Earlier sleep onset is associated with longer nighttime sleep duration during infancy

Objective/backgroundClinical recommendations include putting infants to bed using a consistent bedtime routine at an appropriate hour to promote longer nighttime sleep. Actigraphy was used in this exploratory study to examine how bedtime routines and nighttime sleep onset were associated with nighttime total sleep time (TST) and efficiency from 6 to 24 weeks of age.Patients/methodsInfants (n = 24) wore sleep actigraphs for three, one-week periods at 6, 15, and 24 weeks of age. Nighttime TST, sleep efficiency, sleep onset and offset were quantified. Mothers reported on infant bedtime routines using the Brief Infant Sleep Questionnaire at each age. Multilevel models examined between- and within-person associations.ResultsAs infants aged, sleep onset was earlier, and bedtime routines became shorter (p's < 0.05). Infants fell asleep between 7 and 8:00PM on 24% of the nights. Most mothers (70%) reported that they often fed infants to sleep for the night. For every 1 h earlier in infants' usual sleep onset, nighttime TST was 34.4 min longer that night (p < 0.01). Infants with earlier than usual sleep onset had slightly earlier sleep offset the next morning (8.4 min for every 1 h earlier in onset; p = 0.02). Between-person analyses showed similar patterns. Infants with a more consistent bedtime routine and who were not typically fed to sleep at bedtime had longer nighttime TST at 6 weeks, with a trend or no association at later ages.ConclusionInfants who fell asleep earlier also slept longer at night. Keeping infants up later in hopes of them sleeping in longer may be counterproductive.     

Prevalence,patterns and socio-demographic correlates of sleep duration in adolescents: results from the LabMed study

ObjectiveThe aim of this study was to report the prevalence of adequate sleep and the correlates of sleep duration in Portuguese adolescents aged 12–18 years.MethodsCross-sectional analysis with 1017 adolescents (471 girls) aged 14.6 ± 1.8 years. Adolescents self-reported their sleep duration.ResultsThe percentage of adolescents meeting the guidelines was 72.7%, 60.7% and 51.3%, during a whole week, on weekdays and on weekends, respectively. Boys were always more compliant with the guidelines than girls, for all week categories. A significant difference was found on sleep duration on weekends, between boys and girls (p < 0.001). During weekdays, more adolescents were classified as short sleepers when compared to long sleepers. Younger adolescents were more likely to meet the guidelines over the whole week and on weekdays (OR = 2.23, OR = 2.13, respectively; p < 0.05) and being long sleepers on weekends (OR = 1.49, p < 0.05). Those of medium and low SES were less likely to meet the sleep guidelines for all week categories (p _trend<0.001). Girls were more likely than boys to meet the guidelines or being long sleepers on weekends (OR = 1.78, OR = 2.85, respectively; p < 0.05).ConclusionsDuring weekends, the percentage of girls sleeping more than recommended is high, indicating a clear compensation of low sleep duration during weekdays. Those of low SES and older adolescents were less likely to meet the sleep guidelines. Policy makers and researchers should consider the potential effects that SES, gender and age might have on sleep duration, when designing targeted interventions to promote adequate sleep duration.     

Impact of sleep opportunity on asthma outcomes in adolescents

RationaleInsufficient sleep is associated with a number of negative health outcomes; as most adolescents obtain <7 h of sleep per night, it is important to understand how sleep impacts asthma among adolescents.ObjectivesTo examine the impact of sleep opportunity on asthma in adolescents.MethodsIn this study, 54 adolescents with asthma (12–17 years, 69% female, 65% Caucasian) participated in a randomized, cross-over sleep manipulation trial, including a sleep stabilization week, five nights of a “Short” sleep opportunity (time in bed: 6.5 h/night), and five nights of a “Long” sleep opportunity (time in bed: 9.5 h/night). Wake times were consistent across all three study weeks. Primary outcomes were lung function (daily peak expiratory flow rate, weekly spirometry) and functional asthma outcomes (daily asthma symptoms, Asthma Control Questionnaire, PROMIS Asthma Impact Scale). Markers of inflammation were also explored.Measurements and main resultsCompared to the Long sleep week, during the Short sleep week, morning FEV1 was lower (p = 0.006), while asthma symptoms and albuterol use was higher (p < 0.05), and asthma showed a trend towards greater negative impact on daily life (p = 0.07). No differences were found for weekly measures of lung function or inflammation.ConclusionsAn insufficient sleep opportunity negatively impacts objective and subjective daily symptoms of asthma in adolescents, as well as health related quality of life. As most adolescents are significantly sleep deprived, it is important to target sleep health in the treatment of asthma.     

Light sleep and sleep time misperception – Relationship to alpha–delta sleep

ObjectiveWe investigated the association of alpha–delta sleep (A–DS) with: (1) perception of light sleep and (2) discrepancy between subjective and objective sleep duration.MethodsWe analyzed data from 5764 individuals who underwent polysomnography (PSG) and replied questions about quantity and quality of sleep, including sleep depth. The difference between objectively recorded sleep time and subjectively estimated sleep time was calculated. Alpha–delta sleep (A–DS) was visually scored in a scale from 1 to 4, based on the density and overnight duration of alpha activity and confirmed using spectral array of the electroencephalographic activity.ResultsA–DS scores 1–4 occurred in, respectively, 37.9%; 31.3%; 20.5%; and 6.2% of the cases. ANOVA showed significant difference of light sleep sensation (p < 0.001) and sleep time underestimation (p < 0.001) among the four A–DS categories. Regression to explain both light sleep and sleep time underestimation, controlling for confounders, confirmed A–DS as a significant regressor.ConclusionsThis study of a large prospective sample provides evidence for the association of alpha–delta sleep with subjective sensation of light sleep and with sleep time underestimation.SignificanceAlpha–delta sleep may be a marker of the physiological disorder underlying light sleep and sleep state misperception.     

Insomnia symptoms increase during pregnancy,but no increase in sleepiness - Associations with symptoms of depression and anxiety

ObjectiveTo evaluate alteration in insomnia and sleepiness symptoms during pregnancy and assess early pregnancy risk factors for these symptoms, especially depressive and anxiety symptoms.MethodsA cohort of 1858 women was enrolled from the FinnBrain Birth Cohort Study. Insomnia and sleepiness symptoms were measured in early, mid- and late pregnancy with the Basic Nordic Sleep Questionnaire. Depressive symptoms were measured using the Edinburgh Postnatal Depression Scale and anxiety symptoms with the Symptom Checklist-90/Anxiety Scale. General linear models for repeated measures were conducted.ResultsGeneral sleep quality decreased (p < 0.001) and all insomnia types (p < 0.001) and sleep latencies (p < 0.001) increased as pregnancy proceeded. Snoring increased, but witnessed apneas remained rare. Nevertheless, morning (p = 0.019) and daytime (p < 0.001) sleepiness decreased from early to both mid-pregnancy and late pregnancy (p = 0.006 and p = 0.039). Women took more naps in early and late pregnancy compared to mid-pregnancy (both p < 0.001). Women with higher baseline anxiety symptoms had greater increase in sleep latency. At each pregnancy point, higher depressive and anxiety symptoms were associated with higher insomnia (p < 0.001) and sleepiness scores (p < 0.001) and higher depressive symptoms with longer sleep latencies (p < 0.001).ConclusionWe found a marked increase in insomnia symptoms throughout pregnancy. However, sleepiness symptoms did not increase correspondingly. Both depressive and anxiety symptoms in early pregnancy were associated with higher insomnia and sleepiness symptoms in later stages of pregnancy which emphasizes the importance of their assessment in early pregnancy.     

The effectiveness of diaphragmatic breathing relaxation training for improving sleep quality among nursing staff during the COVID-19 outbreak: a before and after study

ObjectivesRecent studies have demonstrated that first-line nurses involved in the coronavirus disease-2019 (COVID-19) crisis may experience sleep disturbances. As breathing relaxation techniques can improve sleep quality, anxiety, and depression, the current study aimed to evaluate the effectiveness of diaphragmatic breathing relaxation training (DBRT) for improving sleep quality among nurses in Wuhan, China during the COVID-19 outbreak.MethodsThis study used a quasi-experimental (before and after) intervention strategy, with 151 first-line nurses from four wards in Leishenshan hospital. The Pittsburgh Sleep Quality Index (PSQI), Self-Rating Anxiety Scale (SAS), and Self-Rating Depression Scale (SDS) to evaluate the effectiveness of DBRT before and after the intervention. Data were examined using the Shapiro–Wilk test, Levene's test, and paired t-test.ResultsA total of 140 nurses completed the DBRT sessions. First-line nurses achieved significant reductions in global sleep quality (p < 0.01), subjective sleep quality (p < 0.001), sleep latency (p < 0.01), sleep duration (p < 0.001), sleep disturbances (p < 0.001), habitual sleep efficiency (p = 0.015), daytime dysfunction (p = 0.001), and anxiety (p = 0.001). There were no significant reductions in the use of sleeping medication (p = 0.134) and depression (p = 0.359).ConclusionDBRT is a useful non-pharmacological treatment for improving sleep quality and reducing anxiety among first-line nurses involved in the COVID-19 outbreak.The study protocol was clinically registered by the Chinese Clinical Trial Registry. Clinical Trial Registration number: ChiCTR2000032743.     

Impact of a modest delay in school start time in Hong Kong school adolescents

ObjectiveTo examine the effects of a modest delay (15 min) in school start time (SST) on adolescent sleep patterns, mood, and behaviors.MethodsTwo secondary schools in Hong Kong with a total of 1173 students (intervention: n = 617; comparison school n = 556) completed both baseline and follow-up questionnaires. School start time was delayed by 15 min, from 7:45 a.m. to 8:00 a.m., in the intervention school. The comparison school maintained their regular SST at 7:55 a.m. Students' sleep-wake patterns, daytime sleepiness, and mental and behavioral aspects were assessed by validated questionnaires before and after the intervention.ResultsStudents in the intervention school significantly delayed their weekday wake-up time (p < 0.001) and increased their total time in bed (p < 0.001) when compared to students in the comparison school. Both groups experienced a delay in their weekday bedtime. The students in the intervention school showed improved mental health [General Health Questionnaire (GHQ) score, p = 0.015], better prosocial behaviors (p = 0.009), better peer relationships (p < 0.001), greater attentiveness (p < 0.001), less emotional problems (p = 0.002), and less behavioral difficulties (p < 0.001) as measured by Strengths and Difficulties Questionnaire (SDQ).ConclusionsA modest delay (15 min) in school start time can increase adolescent sleep with corresponding improvement in mood and behaviors. Current findings have significant implications for education policy, suggesting that school administrators and policy makers should systematically consider delaying school start time to promote sleep and health among school-aged adolescents.Clinical trial registrationChiCTR-TRC-12002798. The trial protocol can be accessed at: http://www.chictr.org/en/proj/show.aspx?proj=3955.     

Decreased functional connectivity within the salience network after two-week morning bright light exposure in individuals with sleep disturbances: a preliminary randomized controlled trial

BackgroundBright light (BL) exposure is a safe non-pharmacological intervention for sleep disturbances. However, the functional brain correlates underlying the effects of bright light exposure need to be further clarified. As alterations in the salience network were reported in individuals with sleep disturbances, we have investigated whether bright light exposure may improve sleep quality by altering functional connectivity in this network.MethodsIn the current study, 30 individuals with sleep disturbances were randomly assigned to one of the two interventions for two weeks: (1) 1 h of bright light (10,000 lux) exposure (BL-exposed group) and (2) 1 h of dim light (<300 lux) exposure (DL-exposed group). Sleep characteristics and functional connectivity in the salience network were assessed by sleep diary and resting-state functional magnetic resonance imaging, respectively, as outcome measures at before and after the intervention.ResultsAfter two weeks of the intervention, the BL-exposed group showed greater improvement with respect to sleep efficiency (t = 2.27, p = 0.03) and sleep latency (t = −2.40, p = 0.03) as compared to the DL-exposed group. In addition, functional connectivity decreased in the cluster that encompasses the right anterior insular and the frontal opercular regions in the salience network (uncorrected p < 0.001, cluster size>100 mm³) in the BL-exposed group. Decreased functional connectivity in the cluster was associated with decreased sleep latency in the BL-exposed group (β = 0.54, p = 0.01).ConclusionsOur results suggest that bright light exposure may improve sleep quality in individuals with sleep disturbances by modulating functional connectivity in the salience network.Clinical trial registrationhttps://cris.nih.go.kr/cris; KCT0002607.     

Sleep and stress in adolescents: the roles of pre-sleep arousal and coping during school and vacation

Study objectivesThis study explored the relationship between stress and actigraphy-measured and self-reported sleep in adolescents during periods of restricted (school) and unrestricted (vacation) sleep opportunities. We further examined whether (1) cognitive pre-sleep arousal (PSA) mediated the relationship between stress and sleep onset latency (SOL), and (2) coping moderated the effect of stress on PSA.MethodsParticipants were 146 (77 females) adolescents (M = 16.2, SD = 1.0) recruited from the community. Actigraphy assessed daily sleep over the last week of a school-term and the following two-week vacation. The following self-report measures were administered during both school and vacation: the Pittsburgh Sleep Quality Index, Inventory of High-School Students Recent Life Experiences (stress), Pre-Sleep Arousal Scale, and the Brief COPE (coping).ResultsPath analyses showed that during both school and vacation, higher cognitive PSA mediated the relationship between higher stress and longer self-report SOL (p < 0.01). During vacation, higher PSA also mediated the relationship between higher stress and longer actigraphy SOL (p < 0.05). During vacation (but not school), problem-focused coping moderated the mediating effects of PSA (p < 0.05), such that more frequent use of coping was associated with weaker association between stress and cognitive PSA, and shorter actigraphy and self-report SOL.ConclusionsCognitive PSA and coping may be two modifiable factors influencing how stress affects adolescents' sleep onset. Interventions that reduce cognitive arousal at bedtime may therefore shorten adolescents’ sleep onset during both school and vacation. Further, the use of problem-focused coping strategies might be protective against the effects of stress on sleep onset, especially during vacation periods.Statement of significanceThis paper expands the understanding of the stress-sleep association in adolescents by examining the mediating role of cognitive pre-sleep arousal and the moderating effects of coping. By examining these associations during both school and vacation periods, findings are likely to be applicable to both restricted and relatively unconstrained sleep conditions. Practically, our findings suggest that interventions directed towards the reduction of cognitive pre-sleep arousal may improve adolescents' sleep onset latency. Additionally, fostering healthy coping, especially problem-focused coping strategies such as problem solving, may mitigate the effects of stress on adolescents' sleep.     

Sleep duration and obesity in children and adolescents: evidence from an updated and dose–response meta-analysis

Background and objectivesThe association between sleep duration and obesity in children and adolescents has been widely evaluated, whereas the current findings are mixed and prospective studies are limited. To shed more light on this issue and explore the dose–response relationship, we performed the present updated meta-analysis by synthesizing the results of prospective cohorts.MethodsLiterature retrieval, study selection and data extraction were completed independently and in duplicate. Effect-size estimates are expressed as relative risk (RR) with 95% confidence interval (CI) or standardized regression coefficient (β) with standard error.ResultsData from 33 articles, involving 57,848 children and adolescents, were meta-analyzed. Overall analyses revealed statistically significant associations of short (adjusted RR = 1.57, 95% CI: 1.36 to 1.81, P < 0.001) and long sleep duration (0.83, 0.75 to 0.93, 0.001) with obesity. Short sleep duration was also associated with significant changes in body mass index z-score (mean difference = −0.06; 95% CI: −0.09 to −0.04; P < 0.001). By contrast, long sleep duration was identified as a protective factor for childhood obesity. In dose–response analyses, short sleep duration was significantly associated with obesity in toddlers (1–2 years) (adjusted RR = 1.20, 95% CI: 1.07 to 1.34, P = 0.001), preschool-aged (3–5 years) children (1.58, 1.36 to 1.83, <0.001), and school-aged (6–13 years) children (1.82, 1.51 to 2.21, <0.001). In subgroup analyses, geographic region, sleep duration assessment, age, and follow-up interval were possible sources of heterogeneity.ConclusionsOur findings indicate that short sleep duration can increase the risk of obesity in children and adolescents, especially within 3–13 years of age, and long sleep duration seemed beneficial in preventing obesity.     

Work-related rumination and worry at bedtime are associated with worse sleep indicators in schoolteachers: a study based on actigraphy and sleep diaries

Objective/backgroundWork-related rumination and worry are indicators of occupational stress which can impact sleep when they occur close to bedtime. This study examined the relationship between these repetitive thoughts before sleep with objective and subjective sleep parameters.MethodsA microlongitudinal study was carried out with schoolteachers who answered questions on rumination and worry before sleep, wore a wrist actigraph, and completed a sleep diary for 5 to 7 consecutive days. Analysis used mixed-effects repeated measures linear models adjusted for sociodemographic, lifestyle, and health status.ResultsAmong the 134 schoolteachers studied, 64.9% were women and were aged 41.9 ± 9.5 years. In the fully adjusted analysis, actigraphy indicated that a wake-up time <6:30 a.m. was associated with both rumination (relative risk (RR) = 1.67; 95% confidence interval (CI) = 1.21–2.31) and worry (RR = 2.44; 95%CI = 1.63–3.64). Moreover, actigraphy-measured nighttime sleep duration <7 h (RR = 1.23; 95%CI = 1.03–1.47) and self-reported sleep latency >15 min (RR = 1.43; 95%CI = 1.02–2.02) were associated with work-related worry.ConclusionsThe occurrence of work-related repetitive thoughts before sleep, particularly worry about next-day issues, is associated with an increased risk of impaired objective and subjective sleep indicators. These findings suggest that these cognitive processes related to work should be addressed in strategies aimed at preventing and treating sleep disturbances and their individual and occupational consequences.     

Associations between sleep,daytime sleepiness and functional outcomes in adolescents with ADHD

Objective/backgroundAdolescents with attention-deficit/hyperactivity disorder (ADHD) experience greater difficulties in the domains of sleep, daytime sleepiness, and functioning compared to their peers. However, the relationship between these domains has not been fully elucidated. This study aimed to examine the relationship between sleep problems (including daytime sleepiness), ADHD severity, and functional outcomes (irritability, sluggish cognitive tempo, homework difficulties, and substance use) in a sample of adolescents with ADHD.Patients/methodsEighty-two adolescents (13–17 years) and their families participated in the study. Sleep was measured by both adolescent and parent-report. Adolescent irritability and sluggish cognitive tempo were reported by both adolescents and parents, while other variables were reported by a single reporter (homework difficulties – parent; ADHD severity – parent; substance use – adolescent). Analyses controlled for demographic factors and internalising and externalising comorbidities.ResultsA weak relationship was found between adolescent-reported sleep problems and daytime sleepiness, which became non-significant in adjusted analyses (β = −0.19, p = 0.115). In adjusted analyses, there was an association between adolescent-reported sleep problems and adolescent-reported irritability (β = −0.27, p = 0.023) as well as between adolescent-reported daytime sleepiness and parent-reported sluggish cognitive tempo (β = 0.28, p = 0.033). In adjusted analyses, parent-reported adolescent sleep problems were associated with ADHD severity (β = 0.54, p = <0.001), parent-reported sluggish cognitive tempo (β = 0.64, p = <0.001), both reporters of irritability (parent-report: β = 0.32, p = 0.004; adolescent-report: β = 0.29, p = 0.022), and homework problems (β = 0.37, p = 0.003). Parent-reported daytime sleepiness was associated with parent-reported sluggish cognitive tempo (β = 0.34, p = 0.024).ConclusionsThis study demonstrates the importance of a holistic assessment of adolescents with ADHD, not only focusing on symptomatology but also on sleep problems and functional outcomes. The importance of multi-informant assessment of sleep problems is also reinforced.     

Core body temperature changes in school-age children with circadian rhythm sleep–wake disorder

Objective/backgroundCore body temperature (CBT) is considered a valuable marker for circadian rhythm. This study aimed to investigate the changes in CBT that are associated with the symptoms of circadian rhythm sleep–wake disorder (CRSWD) post-treatment in children.Patients/methodsTwenty-eight school-age children [10 boys and 18 girls; mean age (±standard deviation), 13.68 ± 0.93 years] who were admitted to our hospital with CRSWD underwent treatment for 6–8 weeks according to the following protocol: lights-out for sleep at 21:00; phototherapy for waking at 6:00 or 7:00; light exercise everyday (eg, a 20- to 30-min walk). CBT was continuously measured for 24 h on the first day of admission and on the first day after treatment.ResultsThe mean time of sleep onset/offset (±standard deviation; in hours:minutes) 1 week before admission and 1 week after treatment were 23:53 ± 2:26/9:58 ± 2:15 and 21:17 ± 0:19/6:46 ± 0:32, respectively. The mean times of sleep onset and offset measured post-treatment were significantly earlier than those measured pre-treatment (p < 0.001). The mean CBT and mean minimum CBT during sleep were significantly lower on the first day post-treatment than on the first day of admission (p = 0.011 and p < 0.001, respectively).ConclusionsSymptom improvements in patients with CRSWD were associated with a decrease in CBT during sleep, suggesting that CBT may be a biomarker for improvements in CRSWD. These results help elucidate the cause of this sleep disorder.     

Relationship between screen time and sleep among Finnish preschool children: results from the DAGIS study

Study objectivesTo examine the associations between screen time, the time spent on different screen devices, and sleep in a sample of Finnish preschool children.MethodsThe current study analyzed cross-sectional data from the DAGIS study carried out in Finland in 2015–2016 on 736 children aged 3–6 years. Parents reported in a 7-day diary the durations the child used screen devices daily, with separate details about watching TV or DVDs, using tablets or smartphones, and using computers. In addition, parents reported children's bedtimes and wake-up times, which were further used in calculating sleep duration. Parents answered questions regarding their child's sleep consistency. Statistical analyses included adjusted general linear modeling.ResultsAn hourly increase in total screen time was associated with 11 min later bedtime (p < 0.001) and 10 min shorter sleep duration (p < 0.001). More TV/DVD watching was associated with later bedtimes (p = 0.016) and a shorter sleep duration (p = 0.001). More smartphone/tablet use was associated with later bedtimes (p = 0.005), later wake-up times (p = 0.038), and weaker sleep consistency (p = 0.024). More computer use was associated with later bedtimes (p = 0.046). Results did not differ between genders.ConclusionsIncreased screen time was associated with later bedtimes and shorter sleep duration among preschool children. Adverse associations with sleep outcomes were found for each screen device. Attention should be paid to promoting balanced use of screens and regular sleep habits in young children.