Typical Sleep Research Articles

Patterns and reliability of children's skin temperature prior to and during sleep in the home setting.

The relationship between patterns of change in skin temperature and sleep is well recognized. In particular, there is a rapid rise in distal skin temperature (Tdistal) and slower rise in proximal skin temperature (Tproximal) prior to sleep onset. The difference between Tdistal and Tproximal is known as the distal-proximal gradient (DPG). Rise in DPG is known as a measure of distal vasodilation, which contributes to the drop in core body temperature (Tcore) that is important to sleep onset and maintenance. Patterns of change in skin temperature before and during sleep are reported for neonates, infants, adults and elderly, however they are not known for school aged children. Therefore, the current observational study aimed to determine the patterns and reliability of skin temperatures (Tskin) and DPG in relation to sleep of school aged children in their home settings. Participants (22 children, aged 6-12) completed the Children's Sleep Habits Questionnaire and used Thermochron iButtons and actigraphy for four school nights in their typical sleep settings. There were evident patterns of Tskin change before and during sleep. In particular, Tdistal was lower but rose more rapidly than Tproximal after reported bedtime and prior to sleep onset. This reflected a timely rise in DPG, and shows that distal vasodilation precedes sleep onset in school aged children. The measures of Tskin and sleep were practical for children in their home settings, and the observed patterns were consistent across consecutive school nights. Environmental and behavioural strategies that manage skin temperature before and during sleep should be explored for their potential as valuable components of treatment of childhood insomnia.

Increased vulnerability to attentional failure during acute sleep deprivation in women depends on menstrual phase.

To investigate sex differences in the effect of sleep deprivation on performance, accounting for menstrual phase in women. We examined alertness data from 124 healthy women and men (40 women, 84 men; aged 18-30 years) who maintained wakefulness for at least 30 hr in a laboratory setting using a constant routine protocol. Objective alertness was assessed every 2 hr using a 10 min psychomotor vigilance task. Subjective alertness was assessed every hour via the Karolinska Sleepiness Scale. Women in the follicular phase of the menstrual cycle demonstrated the poorest level of performance. This poor performance was most pronounced at times corresponding to the typical sleep episode, demonstrating a window of vulnerability at night during this menstrual phase. At 24 hr awake, over 60 per cent of their responses were lapses of >500 ms and over one-third of their responses were longer lapses of at least 3 s in duration. Women in the luteal phase, however, were relatively protected from alertness failure, performing similar or better than both follicular-phase women and men. These results have important implications for education and intervention programs for shift workers, specifically during times of vulnerability to attentional failure that increase risk of injury.

Overnight Pulse Oximetry Unwoven.

Overnight Pulse Oximetry Unwoven.

Dual Trajectories of Sleep Duration and Cigarette Smoking during Adolescence: Relation to Subsequent Internalizing Problems.

Decreasing sleep duration and increasing cigarette smoking of adolescents are major public health concerns. However, research examining connections between the developmental trajectories of the outcomes that are evolving contemporaneously and their relation to long-term outcomes is still lacking. This study examined distinct trajectories of sleep duration and cigarette smoking during adolescence, associations between these trajectories, and links with internalizing problems during young adulthood. Data were collected from 2510 adolescents who participated in a longitudinal study spanning from 2006 through 2014 in northern Taiwan. Group-based dual trajectory modeling was used to examine the dynamic relationships between sleep duration and cigarette smoking trajectories during adolescence. Multiple linear regression was used to understand the association between the distinct trajectories and subsequent internalizing problems. Three sleep duration trajectories (short decreasing, typical sleep, and long sleep) and three cigarette smoking trajectories (nonsmokers, late increasing, and escalating smokers) were identified. We found significant inter-relationships for sleep duration and cigarette smoking trajectories during adolescence; all atypical sleep duration trajectories conferred increased risks of increased cigarette smoking and vice versa. In addition, the effects of sleep duration and cigarette smoking on later internalizing problems were found to vary by sex and trajectory patterns. These results provide insight regarding the co-development of sleep duration and cigarette smoking trajectories during adolescence. We also highlight the different roles of sleep duration and cigarette smoking trajectories and their relation to internalizing problems of young adulthood.

Psychomotor function measured via online activity predicts motor vehicle fatality risk

Impaired psychomotor performance severely increases the risk of fatal and non-fatal car accidents. However, we currently lack methods to continuously and non-intrusively monitor psychomotor performance. We show we can estimate psychomotor function at population scale from 16 billion observations of typing speeds during the input of web search queries. We show that these estimates exhibit diurnal variation with a substantial increase during typical sleep times, matching published accident risk rates. Further, we show that psychomotor impairment, as measured by keystroke timing, predicts motor vehicle fatality risk on a population level (Spearman ρ = 0.61; p « 10−10). The methods and results highlight a promising direction of harnessing ambient streams of data, such as patterns of interactions with devices, as large-scale sensors to continuously and non-intrusively monitor human psychomotor performance at population scale.

Sleep Patterns and Quality Are Associated with Severity of Obesity and Weight-Related Behaviors in Adolescents with Overweight and Obesity.

Inadequate sleep duration, sleep patterns, and sleep quality have been associated with metabolic, circadian, and behavioral changes that promote obesity. Adolescence is a period during which sleep habits change to include less sleep, later bedtimes, and greater bedtime shift (e.g., difference between weekend and weekday bedtime). Thus, sleep may play a role in adolescent obesity and weight-related behaviors. This study assesses sleep duration, quality, and schedules and their relationships to relative weight and body fat percentage as well as diet, physical activity, and screen time in adolescents with overweight/obesity. Adolescents between 12 and 17 years old (n = 186) were weighed and measured, reported typical sleep and wake times on weekdays and weekends, and responded to questionnaires assessing diet, physical activity, and screen time habits. Controlling for sleep duration, later weekend bedtime and greater bedtime shift were associated with greater severity of overweight (β = 0.20; β = 0.16) and greater screen time use (β = 0.22; β = 0.2). Later bedtimes on the weekdays and weekends were associated with fewer healthy diet practices (β = -0.26; β = -0.27). In addition, poorer sleep quality was associated with fewer healthy diet habits (β = -0.21), greater unhealthy diet habits (β = 0.15), and less physical activity (β = -0.22). Sleep duration was not associated with any weight or weight-related behavior. Sleep patterns and quality are associated with severity of overweight/obesity and various weight-related behaviors. Promoting a consistent sleep schedule throughout the week may be a worthwhile treatment target to optimize behavioral and weight outcomes in adolescent obesity treatment.

The effects of low-intensity cycling on cognitive performance following sleep deprivation

This study examined the effect of 24h of sleep deprivation on cognitive performance and assessed the effect of acute exercise on cognitive performance following sleep deprivation. Young, active, healthy adults (n=24, 14 males) were randomized to control (age=24.7±3.7years, BMI=27.2±7.0) or exercise (age=25.3±3.3years, BMI=25.6±5.1) groups. Cognitive testing included a 5-min psychomotor vigilance task (PVT), three memory tasks with increasing cognitive load, and performance of the PVT a second time. On morning one, cognitive testing followed a typical night's sleep. Following 24-h of sustained wakefulness, cognitive testing was conducted again prior to and after the acute intervention. Participants in the exercise condition performed low-intensity cycling (∼40%HRR) for 15-min and those in the control condition sat quietly on the bike for 15-min. t-Tests revealed sleep deprivation negatively affected performance on the PVT, but did not affect memory performance. Following the acute intervention, there were no cognitive performance differences between the exercise and rested conditions. We provide support for previous literature suggesting that during simple tasks, sleep deprivation has negative effects on cognitive performance. Importantly, in contrast to previous literature which has shown multiple bouts of exercise adding to cognitive detriment when combined with sleep deprivation, our results did not reveal any further detriments to cognitive performance from a single-bout of exercise following sleep deprivation.

Sleep and psychiatric symptoms in young child psychiatric outpatients.

Sleep may underlie psychiatric symptoms in young children. However, not many studies have reported on sleep and its associations with symptoms in young child psychiatric patients. To assess the amount and quality of sleep and how sleep associates with psychiatric symptoms in young child psychiatric patients. Furthermore, we evaluated how sleep and daytime somnolence differed in patients and their age- and gender-matched controls. The sample consisted of 139 3- to 7-year-old child psychiatric outpatients and 139 age- and gender-matched controls from community. We evaluated sleep and daytime somnolence with the Sleep Disturbance Scale for Children in all children and psychiatric symptoms with Child Behaviour Checklist (CBCL) in the patient group. Family background information was collected from the patients. Of the patients, 31.6% had a significant sleep problem and 14.4% slept too little. The most typical sleep problems were restless sleep (31.7%), morning tiredness (21.6%) and difficulties getting to sleep at night (18.7%). All types of sleep problems were associated with CBCL total, internalising and externalising problems (all p-values < .01). We observed a strong association between all types of sleep problems and emotionally reactive subscale ( p-value < .001). Furthermore, parent-reported sleep problems increased significantly the risk of having high scores on total (odds ratio (OR) = 5.3, 95% confidence interval (CI) = [2.2, 12.6], p < .001), external (OR = 3.7, 95%, CI = [1.6, 8.5], p < .01) and internal (OR = 2.5, 95% CI = [1.1, 5.5], p < .05) scores after controlling for age, gender, family structure and parent's educational level. Even mild sleep disturbance increased the intensity of psychiatric symptoms. Compared to controls, patients slept less ( p < .001) and had significantly more frequent restless sleep, nightmares and morning and daytime somnolence. Sleep problems and too little sleep are prevalent in young child psychiatric patients, and they relate strongly to the intensity of psychiatric symptoms. Identification and treatment of sleep problems should be a routine part of the treatment plan for young child psychiatric patients. The results emphasise the need for assessing sleep in young child psychiatric patients, as treating the sleep problem may reduce psychiatric symptoms.

Military Recruits Who Typically Sleep &lt;6 Hours Miss Training Due To Upper Respiratory Infection

The National Sleep Foundation recommends 7−9 hours of sleep per night for young adults. Habitually sleeping <6 hours per night has been shown to lower immunity and increase susceptibility to common cold following exposure to rhinovirus. However, no investigations have examined the importance of sleep duration on upper respiratory infection (URTI) and loss of training days in military recruits. PURPOSE: To identify if military recruits who typically sleep <6 hours per night during training suffer a greater incidence of URTI and, as a consequence, miss more training than recruits who meet sleep recommendations. METHODS: Participants included 651 British Army recruits aged 22 ± 3 years who completed 13 weeks of Phase 1 military training (67% males, 33% females). Recruits were members of 21 platoons (11 male, 10 female) who commenced training across the seasons (19% winter, 19% spring, 28% summer, and 33% autumn). At week 13, participants completed a questionnaire asking the normal time they went to sleep and awoke during training. Incidence of physician-diagnosed URTI and reduced or missed training days due to URTI were retrieved from medical records. RESULTS: Typical sleep duration during training was reported as 7.0 ± 0.8 hours per night with 5% of recruits reporting they normally slept <6 hours and 60% of recruits reporting 7-9 hours of sleep each night. In a logistic regression model, recruits who slept <6 hours per night were 4 times more likely to be diagnosed with URTI compared with recruits who slept 7−9 hours per night after controlling for sex, BMI, alcohol, smoking, and season of recruitment (OR 4.6; 95% CI, 1.7–12.8, P < 0.01). URTI’s diagnosed in recruits who slept <6 hours were spread across both sexes, 5 platoons and 3 seasons, showing sufficient heterogeneity. Overall, 49 recruits (8%) were diagnosed with at least one URTI, and 3 recruits (<1%) were diagnosed with two URTI’s. On average, each URTI resulted in 2.9 ± 1.5 reduced or missed training days. CONCLUSION: These findings show that military recruits who sleep <6 hours per night are more susceptible to URTI and miss more training due to URTI. Future studies should examine interventions to improve sleep hygiene in military training. Supported by MoD, UK.

Amount of Sleep, Daytime Sleepiness, Hazardous Driving, and Quality of Life of Second Year Medical Students.

The authors describe the sleep habits of second year medical students and look for associations between reported sleep duration and depression, burnout, overall quality of life, self-reported academic success, and falling asleep while driving. The authors conducted a cross-sectional descriptive study of two consecutive cohorts of second year medical students at a large public university in the USA. Participants completed an anonymous survey about their sleep habits, daytime sleepiness (Epworth sleepiness scale), burnout (Maslach burnout inventory), depression (PRIME MD), and perceived stress (perceived stress scale). Categorical and continuous variables were compared using chi square tests and t tests, respectively. Sixty-eight percent of the students responded. Many (34.3%) reported fewer than 7h of sleep on typical weeknights, including 6.5% who typically sleep less than 6h. Twenty-five students (8.4%) reported nodding off while driving during the current academic year. Low typical weeknight sleep (fewer than 6h vs 6-6.9h vs 7 or more hours) was associated with (1) higher Epworth sleepiness scale scores, (2) nodding off while driving, (3) symptoms of burnout or depression, (4) decreased satisfaction with quality of life, and (5) lower perceived academic success (all p values ≤0.01). Students reporting under 6h of sleep were four times more likely to nod off while driving than those reporting 7h or more. Educational, behavioral, and curricular interventions should be explored to help pre-clinical medical students obtain at least 7h of sleep most on weeknights.

Sleep quality, duration, and breast cancer aggressiveness.

Epidemiological studies suggest that short sleep duration and poor sleep quality may increase breast cancer risk. However, whether sleep is associated with breast tumor aggressiveness characteristics has largely been unexplored. The study included 4171 non-Hispanic whites (NHW) and 235 African Americans (AA) diagnosed with incident, primary, invasive breast cancer in the Women's Health Initiative (WHI) Observational Study (1994-2013). We used logistic regression to examine the association of baseline sleep (sleep duration, sleep quality, WHI Insomnia Rating Scale) with tumor grade, stage, hormone receptor status, HER2 status. In NHW, women who reported 6h of sleep/night were more likely to have tumors classified as regional/distant stage at diagnosis compared to women who slept 7-8h/night (adjusted odds ratio (OR): 1.25, 95% confidence interval (CI): 1.05-1.48). AA women who reported their typical night's sleep as 'average quality' or 'restless or very restless sleep' were more likely to be diagnosed with triple-negative tumors than those who reported 'sound or restful' sleep (adjusted ORs: 2.91 (1.11, 7.63) and 3.74 (1.10, 12.77), respectively). Our findings provide indications that aspects of sleep (sleep duration and quality), partially modifiable health behaviors, may be associated with development of aggressive tumor characteristics in postmenopausal women. The role of these sleep attributes may differ for NHW and AA women; however, further study in robust, racial diverse samples is needed. This study provides evidence that facets of sleep behavior are associated with the development of aggressive tumor features and these associations differ by race.

Kleefstra syndrome: Considerations about treatment strategy in 2 patients with a causative Ehmt1 mutation and apathy

IntroductionKleefstra syndrome [OMIM: 610253] is caused by a 9q34.3 micro-deletion or an intragenic mutation in the EHMT1 gene. Its core phenotype comprises intellectual disability, childhood hypotonia and distinct dysmorphisms. The syndrome can be associated with congenital anomalies, epilepsy, cardiac arrhythmias and a typical sleep pattern. Starting from adult age, a regressive phenotype may develop.ObjectivesFurther delineation of the neuropsychiatric phenotype.AimsFormulating a comprehensive treatment approach.MethodsDetailed examination of two patients with EHMT1 mutation.ResultsPatient 1, male aged 34 years, showed recurrent behavioral problems with aggression and self-injuries as well as obstipation. Elsewhere, a diagnosis of autism was established. Aged 24, he suffered from some epileptic seizures. Recently, paroxysmal atrial fibrillation was diagnosed. Neither treatment with pipamperone and risperidone nor with valproate was effective for behavioral control. Array analysis and metabolic screening did not reveal abnormalities. Whole exome sequencing revealed an intragenic EHMT1 mutation. Patient 2, female aged 53 years, was known with childhood epilepsy and developed gradual decline of general functioning with motor slowing from her third decade. In her thirties, a mood/anxiety disorder was suspected for which several antidepressants were given without any effect. Array analysis was normal. A pathogenic nucleotide deletion was identified resulting in a frame-shift in exon 21 of the EHMT1 gene. In both patients marked apathy was observed (AES = 62 and 64, respectively).ConclusionsApathy syndrome in Kleefstra syndrome should be differentiated from depression and autism. Apart from treatment with selected psychotropics, individually targeted contextual measures should always be implemented.Disclosure of interestThe authors have not supplied their declaration of competing interest.

Night and day variations of sleep in patients with disorders of consciousness

Brain injuries substantially change the entire landscape of oscillatory dynamics and render detection of typical sleep patterns difficult. Yet, sleep is characterized not only by specific EEG waveforms, but also by its circadian organization. In the present study we investigated whether brain dynamics of patients with disorders of consciousness systematically change between day and night. We recorded ~24 h EEG at the bedside of 18 patients diagnosed to be vigilant but unaware (Unresponsive Wakefulness Syndrome) and 17 patients revealing signs of fluctuating consciousness (Minimally Conscious State). The day-to-night changes in (i) spectral power, (ii) sleep-specific oscillatory patterns and (iii) signal complexity were analyzed and compared to 26 healthy control subjects. Surprisingly, the prevalence of sleep spindles and slow waves did not systematically vary between day and night in patients, whereas day-night changes in EEG power spectra and signal complexity were revealed in minimally conscious but not unaware patients.

Sleep duration and chronic kidney disease: The Korean Genome and Epidemiology Study (KoGES)-Kangwha study.

Background/AimsSleep duration affects health in various ways. The objective of this study was to investigate the associations of sleep duration with chronic kidney disease (CKD) in a Korean adult population.MethodsThis cross-sectional analysis was conducted for total of 1,360 participants who completed baseline health examinations for the Korean Genome and Epidemiology Study-Kangwha study in 2010 to 2011. Sleep habits were measured by an interviewer-assisted questionnaire. Sleep duration was calculated based on the number of hours per day participants had slept over the past 1 year. CKD was defined as either proteinuria or estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2. Multiple logistic regression models were applied to examine associations between sleep duration and CKD.ResultsWomen with very long sleep duration (≥ 9 hours/day) were at significantly increased odds for having high serum creatinine (odds ratio [OR], 2.936; 95% confidence interval [CI], 1.176 to 7.326), low eGFR (OR, 3.320; 95% CI, 1.372 to 8.034), and CKD (OR, 3.112; 95% CI, 1.315 to 7.363), compared those with a typical sleep duration (7 to < 8 hours/day), after adjusting for sociodemographic status, socioeconomic status, health behaviors, comorbidities, and sleep quality. Among women, for every 1 hour increase in sleep duration per day, there was a 24.6% increase in the presence of CKD (OR, 1.246; 95% CI, 1.019 to 1.523). However, among men, sleep duration was not significantly associated with CKD.ConclusionsVery long sleep duration was independently associated with a higher prevalence of CKD among Korean women. Gender may influence this association.

A Respiration-Derived Posture Method Based on Dual-Channel Respiration Impedance Signals

Sleep posture has been used as a sleep assessment indicator in home health monitoring and clinical monitoring in recent years. Considering comfort and usability, unobtrusive sleep posture detection is needed. In this paper, we proposed a novel sleep respiration-derived posture (RDP) method based on left and right lung respiration impedance signals. We developed a dual-channel respiratory impedance acquisition system with wireless transmission. Then, support vector machine using radial basis function kernel was applied to recognize four typical sleep postures. Moreover, the performance of the SVM classifier was improved by using backward elimination. In-situ experiments with 16 subjects indicated that the RDP method reached an accuracy of 99.67%. Thus, our method is reliable in sleep posture recognition. Furthermore, a whole-night monitoring system based on respiration impedance can be conducted for sleep quality assessment.

A longitudinal study of sleep duration in pregnancy and subsequent risk of gestational diabetes: findings from a prospective, multiracial cohort

Both short and prolonged sleep duration have been linked to impaired glucose metabolism. Sleep patterns change during pregnancy, but prospective data are limited on their relation to gestational diabetes. We sought to prospectively examine the trimester-specific (first and second trimester) association between typical sleep duration in pregnancy and subsequent risk of gestational diabetes, as well as the influence of compensatory daytime napping on this association. In the prospective, multiracial Eunice Kennedy Shriver National Institute of Child Health and Human Development Fetal Growth Studies-Singleton Cohort, 2581 pregnant women reported their typical sleep duration and napping frequency in the first and second trimesters. Diagnosis of gestational diabetes (n= 107; 4.1%) was based on medical records review. Adjusted relative risks with 95% confidence intervals for gestational diabetes were estimated with Poisson regression, adjusting for demographics, prepregnancy body mass index, and other risk factors. From the first and second trimester, sleep duration and napping frequency declined. Sleeping duration in the second but not first trimester was significantly related to risk of gestational diabetes. The association between second-trimester sleep and gestational diabetes differed by prepregnancy obesity status (P for interaction= .04). Among nonobese but not obese women, both sleeping >8-9 hours or <8-9 hours were significantly related to risk of gestational diabetes: 5-6 hours (adjusted relative risk, 2.52; 95% confidence interval, 1.27-4.99); 7 hours (adjusted relative risk, 2.01; 95% confidence interval, 1.09-3.68); or ≥10 hours (adjusted relative risk, 2.17; 95% confidence interval, 1.01-4.67). Significant effect modification by napping frequency was also observed in the second trimester (P for interaction= .03). Significant and positive association between reduced sleep (5-7 hours) and gestational diabetes was observed among women napping rarely/never (adjusted relative risk, 2.48; 95% confidence interval, 1.20-5.13), whereas no comparable associations were observed among women napping most/sometimes. Our data suggest a U-shaped association between sleep duration and gestational diabetes, and that napping and prepregnancy obesity status may modify this association.

Bedtime and evening light exposure influence circadian timing in preschool-age children: A field study

Light exposure and sleep timing are two factors that influence inter-individual variability in the timing of the human circadian clock. The aim of this study was to quantify the degree to which evening light exposure predicts variance in circadian timing over and above bedtime alone in preschool children. Participants were 21 children ages 4.5–5.0 years (4.7±0.2 years; 9 females). Children followed their typical sleep schedules for 4 days during which time they wore a wrist actigraph to assess sleep timing and a pendant light meter to measure minute-by-minute illuminance levels in lux. On the 5th day, children participated in an in-home dim-light melatonin onset (DLMO) assessment. Light exposure in the 2h before bedtime was averaged and aggregated across the 4 nights preceding the DLMO assessment. Mean DLMO and bedtime were 19:22±01:04 and 20:07±00:46, respectively. Average evening light exposure was 710.1±1418.2lux. Children with later bedtimes (lights-off time) had more delayed melatonin onset times (r=0.61, p=0.002). Evening light exposure was not independently associated with DLMO (r=0.32, p=0.08); however, a partial correlation between evening light exposure and DLMO when controlling for bedtime yielded a positive correlation (r=0.46, p=0.02). Bedtime explained 37.3% of the variance in the timing of DLMO, and evening light exposure accounted for an additional 13.3% of the variance. These findings represent an important step in understanding factors that influence circadian phase in preschool-age children and have implications for understanding a modifiable pathway that may underlie late sleep timing and the development of evening settling problems in early childhood.

Modifiable risk factors for chronic back pain: insights using the co-twin control design

BackgroundInconsistent associations between modifiable risk factors and chronic back pain (CBP) may be due to the inability of traditional epidemiologic study designs to properly account for an array of potential genetic and environmental confounding factors. The co-twin control research design, comparing modifiable risk factors in twins discordant for CBP, offers a unique way to remove numerous confounding factors. PurposeThe study aimed to examine the association of modifiable lifestyle and psychological factors with lifetime CBP. Study Design/SettingThis is a cross-sectional co-twin control study in a nationwide sample of male twin members of the Vietnam Era Twin Registry. Patient SampleThe sample is composed of 7,108 participants, including 1,308 monozygotic (MZ) pairs and 793 dizygotic pairs. Outcome MeasureThe outcome measure is the self-reported lifetime history of CBP. MethodsLifestyle factors included body mass index (BMI), smoking history, alcohol consumption, habitual physical activity, and typical sleep duration. Psychological factors included depression (Patient Health Questionnaire-9) and posttraumatic stress disorder (PTSD) symptoms (PTSD Checklist). Covariates included age, race, education, and income. Odds ratios (ORs) and 95% confidence intervals (CI) were estimated for the association of risk factors with lifetime CBP when considering twins as individuals, and a within-pair co-twin control analysis that accounted for familial and genetic factors. Funding was through VA Grant 5IK2RX001515; there were no study-specific conflicts of interest. ResultsThe mean age of respondents was 62 years and the prevalence of lifetime CBP was 28%. All lifestyle factors were associated with CBP in the individual level analysis. However, none of these persisted in the within-pair analyses, except for severe obesity (BMI ≥35.0), which was associated with lifetime CBP in both individual-level (OR=1.6, 95% CI: 1.3–1.9) and within-pair analyses (MZ analysis: OR=3.7, 95% CI: 1.2–11.4). Symptoms of PTSD and depression were strongly associated with lifetime CBP in both the individual-level (moderate or severe depression: OR=4.2, 95% CI: 3.6–4.9, and severe PTSD: OR=4.8, 95% CI: 4.0–5.7) and within-pair (MZ) analyses (moderate or severe depression: OR=4.6, 95% CI: 2.4–8.7, and severe PTSD: OR=3.2, 95% CI: 1.6–6.5). ConclusionsMany associations between modifiable lifestyle risk factors and CBP are due to confounding by familial and genetic factors. Severe obesity, depression, and PTSD should be considered in the development of intervention strategies to reduce the prevalence of CBP.

Effect of sleep extension on sluggish cognitive tempo symptoms and driving behavior in adolescents with chronic short sleep

Objective/backgroundFew adolescents report obtaining adequate amounts of sleep. Correlational studies have linked adolescent short sleep with driving crashes and sluggish cognitive tempo (SCT), a cluster of symptoms that include sluggishness and low persistence that are related to but distinct from inattention and sleepiness. The relationship between SCT and driving is understudied, and no study has experimentally examined the relationship between SCT and sleep. We examined the relationship between SCT and driving problems in a sample of chronically short-sleeping adolescents. We also examined whether experimentally extending sleep improved SCT and driving behaviors. Participants/MethodsLicensed 16- to 18-year-old adolescents who regularly obtained five to seven hours of sleep completed a five-week at-home experimental protocol: a baseline week to determine typical sleep (TYP), followed in a counterbalanced order by two-week spans in which school-night bedtimes and rise times were (a) matched to TYP or (b) modified to extend (EXT) time in bed by 1.5 h/night. Sleep was monitored by actigraphy. Self- and parent-reported SCT and inattention and self-reported driving problems were recorded at baseline and following each condition. Of the 38 eligible participants who completed the baseline session, 24 completed all five weeks of the protocol. ResultsAfter controlling for inattention, only parent-reported SCT was significantly positively associated with self-reported purposeful driving violations at baseline. Adolescents reported lesser SCT during EXT than during TYP. Further, after controlling for inattention, participants who reported improvement in SCT demonstrated fewer driving problems during EXT than during TYP. ConclusionsPreliminary findings suggest that extending sleep in short-sleeping adolescents may help alleviate SCT symptoms and improve driving.

Period 3 gene polymorphism and sleep adaptation to stressful urban environments.

This study's objective was to investigate the relationship between a variable-number tandem-repeat (VNTR) Period 3 gene (PER3) polymorphism and sleep adaptation to stressful urban environments. Seventy-five (49 female) African American participants (ages 18-35years) living in neighbourhoods with high rates of violent crime were selected for the study based on converging criteria for good or poor sleep. Categorization of sleep quality was based on the Insomnia Severity Index (ISI), estimates of typical sleep duration and sleep efficiency. Other assessments included the Fear of Sleep Index (FOSI) and City Stress Inventory (CSI). Whole blood DNA was analysed for the 4 and 5 VNTR alleles using polymerase chain reaction (PCR) and restrictive enzyme digestion. Fifty-seven per cent of those who were homo- or heterozygous for the 4-repeat allele were poor sleepers versus 25% of those homozygous for the 5-repeat allele; χ2 =4.17, P=0.041. In a logistic regression model with all the variables with significant bivariate relationships to sleep quality group, FOSI was the only significant predictor (χ2 =5.68, P=0.017). FOSI scores were higher among those with the 4-repeat allele (t=2.66, P=0.013). The PER3 4 and 5 VNTR polymorphisms appear to influence sensitivity to the effects of stressful urban environments on sleep. While FOSI was the only variable associated independently with sleep quality category, the candidate vulnerability allele was also associated with greater 'fear of sleep'.