Sleep-wake Variables Research Articles

The Relationship Between Intraindividual Sleep-Wake Variability and Mental Health in Adolescents

The Relationship Between Intraindividual Sleep-Wake Variability and Mental Health in Adolescents

Sleep-wake behaviors associated with cognitive performance in middle-aged participants of the Hispanic Community Health Study/Study of Latinos

ObjectivesMany sleep-wake behaviors have been associated with cognition. We examined a panel of sleep-wake/activity characteristics to determine which are most robustly related to having low cognitive performance in midlife. Secondarily, we evaluate the predictive utility of sleep-wake measures to screen for low cognitive performance. MethodsThe outcome was low cognitive performance defined as being >1 standard deviation below average age/sex/education internally normalized composite cognitive performance levels assessed in the Hispanic Community Health Study/Study of Latinos. Analyses included 1006 individuals who had sufficient sleep-wake measurements about 2years later (mean age=54.9, standard deviation= 5.1; 68.82% female). We evaluated associations of 31 sleep-wake variables with low cognitive performance using separate logistic regressions. ResultsIn individual models, the strongest sleep-wake correlates of low cognitive performance were measures of weaker and unstable 24-hour rhythms; greater 24-hour fragmentation; longer time-in-bed; and lower rhythm amplitude. One standard deviation worse on these sleep-wake factors was associated with ∼20%-30% greater odds of having low cognitive performance. In an internally cross-validated prediction model, the independent correlates of low cognitive performance were: lower Sleep Regularity Index scores; lower pseudo-F statistics (modellability of 24-hour rhythms); lower activity rhythm amplitude; and greater time in bed. Area under the curve was low/moderate (64%) indicating poor predictive utility. ConclusionThe strongest sleep-wake behavioral correlates of low cognitive performance were measures of longer time-in-bed and irregular/weak rhythms. These sleep-wake assessments were not useful to identify previous low cognitive performance. Given their potential modifiability, experimental trials could test if targeting midlife time-in-bed and/or irregular rhythms influences cognition.

Sleep Disturbance in Bipolar Disorder. Treatment Implications

IntroductionRelationship between sleep and bipolar disorder involves the following aspects: decreased need for sleep is a fundamental marker of the manic state, sleep deprivation is one cause of mania and may in fact be a fundamental etiological agent in mania, total sleep time is a predictor of future manic episodes, and total sleep time may be a marker of response as well as a target of treatment in mania.ObjectivesThis e-poster aimed to summarize evidence regarding the sleep disturbance in Bipolar Disorder.MethodsBibliopgraphical review was performed using PubMed platform. All relevant articles were found using the keywords: sleep disturbance, bipolar disorder, mania.ResultsSleep disturbances are frequent in BD patients in different phases of illness, including the euthymic state and remission. These sleep aberrations are represented not only by insomnia but also by sleep–wake rhythm disorders, especially delayed sleep–wake phase disorders. During the manic state, most patients experience a reduced need for sleep and longer sleep onset latency. Likewise, in the depressive state, insomnia and hypersomnia are commonly observed. Meta-analyses of trials conducted on remitted BD patients demonstrated prolonged total sleep time, increased awakenings after sleep onset, greater variability of sleep–wake variables, and reduced sleep efficiency.ConclusionsOverall, all kinds of sleep disorders and parasomnias are very common especially in youth patients with BD. Thus, compared to the general population, youth with BD exhibit lower sleep efficiency, longer slow wave sleep, and reduced REM sleep, features that could affect the genesis and prognosis of the disorder. Sleep disturbances may also be used as predictors of the onset of BD in a subset of high-risk young subjects.Disclosure of InterestNone Declared

Sleep-wake monitoring of people with intellectual disability: Examining the agreement of EMFIT QS and actigraphy.

Gaining insight into sleep-wake patterns of persons with intellectual disabilities is commonly done using wrist actigraphy. For some people, contactless alternatives are needed. This study compares a contactless bed sensor with wrist actigraphy to monitor sleep-wake patterns of people with moderate to profound intellectual disabilities. Data were collected with EMFIT QS (activity and presence) and MotionWatch 8/Actiwatch 2 (activity, ambient light, and event marker/sleep diary) for 14 nights in 13 adults with moderate-profound intellectual disabilities residing in intramural care. In a care-as-usual setting, EMFIT QS and actigraphy assessment show little agreement on sleep-wake variables. Currently, EMFIT QS should not be considered an alternative to wrist actigraphy for sleep-wake monitoring. Further research is needed into assessing sleep-wake variables using (contactless) technological devices and how the data should be interpreted within the care context to achieve reliable and valid information on sleep-wake patterns of people with intellectual disabilities.

Dynamic modelling of chronotype and hypo/manic and depressive symptoms in young people with emerging mental disorders

ABSTRACT There is significant interest in the possible influence of chronotype on clinical states in young people with emerging mental disorders. We apply a dynamic approach (bivariate latent change score modelling) to examine the possible prospective influence of chronotype on depressive and hypo/manic symptoms in a youth cohort with predominantly depressive, bipolar, and psychotic disorders (N = 118; 14–30-years), who completed a baseline and follow-up assessment of these constructs (mean interval = 1.8-years). Our primary hypotheses were that greater baseline eveningness would predict increases in depressive but not hypo/manic symptoms. We found moderate to strong autoregressive effects for chronotype (β = -0.447 to −0.448, p < 0.001), depressive (β = -0.650, p < 0.001) and hypo/manic symptoms (β = -0.819, p < 0.001). Against our predictions, baseline chronotypes did not predict change in depressive (β = -0.016, p = 0.810) or hypo/manic symptoms (β = 0.077, p = 0.104). Similarly, the change in chronotype did not correlate with the change in depressive symptoms (β = -0.096, p = 0.295) nor did the change in chronotype and the change in hypo/manic symptoms (β = -0.166, p = 0.070). These data suggest that chronotypes may have low utility for predicting future hypo/manic and depressive symptoms in the short term, or that more frequent assessments over longer periods are needed to observe these associations. Future studies should test whether other circadian phenotypes (e.g. sleep-wake variability) are better indicators of illness course.

Adolescents' sleep and adjustment: Reciprocal effects.

Reciprocal relations between sleep and adjustment were investigated. Participants included 246 adolescents (M=15.80years; 67.5% White, 32.5% Black/African American; 53% female, 47% male) at Time 1 (data collected 2012-2013), 227 at Time 2 (M=16.78years) and 215 at Time 3 (M=17.70years). Sleep-wake variables were measured with self-reports (sleepiness) and actigraphy (average sleep minutes and efficiency, variability in sleep minutes and efficiency). Adolescents reported on depression and anxiety symptoms, and parents reported on externalizing problems. Greater variability in sleep duration and efficiency as well as sleepiness predicted adjustment problems (range of R2 : 36%-60%). Reciprocal relations were supported mostly for sleepiness (range of R2 : 16%-32%). Results help understand bidirectional relations between sleep and adjustment.

Social Jetlag and Excessive Daytime Sleepiness from a Sample of Russian Children and Adolescents.

PurposeInsufficient nocturnal sleep is a primary source of excessive daytime sleepiness. Most previous research has focused on the disparity between sleep demands and study start times in adolescents. Fewer studies have focused on elementary schoolchildren. We hypothesize that late sleep timing is connected to excessive daytime sleepiness in a sample of Russian children and adolescents. The major goals of our study were to evaluate excessive daytime sleepiness in Russian schoolchildren and adolescents using the Russian version of the Pediatric Daytime Sleepiness Scale (PDSS) and to estimate its relationship with sleep-wake parameters using the Munich Chronotype Questionnaire (MCTQ).Materials and MethodsStudent subjects were from public educational facilities in the Republic of Karelia. They completed both the PDSS and the Munich Chronotype Questionnaire to estimate sleep parameters and chronotype (MSFsc). Five hundred and eleven students provided data for the PDSS and sleep-wake variables, and 479 for the full MCTQ data.ResultsThe overall prevalence of Excessive Daytime Sleepiness (EDS) in our sample was 18%. The total PDSS score was inversely correlated with sleep length on school nights and was independent of respondents’ sex. Higher PDSS scores were associated with later bedtimes on school days and free days, and shorter sleep duration on school days. Late chronotype and more pronounced social jetlag were both positively correlated with high PDSS scores. A negative correlation was found between chronotype and the duration of the sleep period on weekdays (p < 0.001) and a positive correlation was found on weekends (p < 0.001). Longer average sleep duration was positively related to less daytime sleepiness.ConclusionThis study suggests that excessive daytime sleepiness is chronotype-dependent. School start times could be shifted to a later hour to prolong sleep and reduce EDS.

Sleep-wake characteristics, daytime sleepiness, and glycemia in young adults with type 1 diabetes.

The purpose of this study was to describe objective sleep-wake characteristics and glycemia over 7-14 days in young adults with type 1 diabetes. In addition, person-level associations among objective sleep-wake characteristics (total sleep time, sleep variability, and sleep fragmentation index), daytime sleepiness, and glycemia (glycemic control and glucose variability) were examined. In this cross-sectional study, objective sleep-wake characteristics were measured via actigraphy and glucose variability via continuous glucose monitoring over 6-14 days. At baseline, participants completed the Psychomotor Vigilance Test, the Trail Making Test, and questionnaires on daytime sleepiness, sleep quality, and sleep disturbance including sleep diaries. Forty-six participants (mean age, 22.3 ± 3.2 years) wore a wrist actigraph and underwent continuous glucose monitoring concurrently for 6-14 days. Greater sleep variability was directly associated with greater glucose variability (mean of daily differences; r = .33, P = .036). Higher daytime sleepiness was directly associated with greater glucose variability (mean of daily differences; r = .50, P = .001). The association between sleep variability and glucose variability (mean of daily differences) was no longer significant when accounting for daytime sleepiness and controlling for type 1 diabetes duration (P > .05). A higher sleep fragmentation index was associated with greater glucose variability (B = 1.27, P = .010, pr2 = 0.40) after controlling for type 1 diabetes duration and accounting for higher daytime sleepiness. Sleep-wake variability, sleep fragmentation, daytime sleepiness, and the associations with glycemia are new dimensions to consider in young adults with type 1 diabetes. Sleep habits in this population may explain higher glucose variability, and optimizing sleep may improve overall diabetes management. Griggs S, Hickman RL Jr, Strohl KP, Redeker NS, Crawford SL, Grey M. Sleep-wake characteristics, daytime sleepiness, and glycemia in young adults with type 1 diabetes. J Clin Sleep Med. 2021;17(9):1865-1874.

Mode of Delivery of Cognitive Behaviour Therapy for Insomnia: A Randomized Controlled Non-Inferiority Trial of Digital or Face-to-Face Therapy

Background: Digital CBT-I (dCBT-I) has demonstrated significant efficacy in reducing insomnia severity in self-referred and community samples. It is unknown, however, how dCBT-I compares to individual face-to-face (FtF) CBT-I for individuals referred to clinical secondary care services. Methods: Parallel-group non-inferiority randomized controlled trial of fully automated dCBT-I versus FtF CBT-I. Eligible participants were adults with insomnia referred to a sleep clinic via public mental health services in Norway. The primary outcome measure was the Insomnia Severity Index (ISI). The non-inferiority margin was defined a priori as 2-points on the ISI at week 33 post-randomization i.e. dCBT-I is non-inferior if the 95% Confidence Interval (CI) for the mean difference is between -2 and ∞, whilst individual FtF CBT-I is superior if the 95% CI is between -∞ and 0. Secondary outcomes were tested using superiority analyses. These were sleep-wake variables, psychological distress and fatigue. Findings: Between October 2014 and January 2016, 101 patients from 288 potential participants were recruited. Individuals were randomized to FtF CBT-I (n=52) or dCBT-I (n=49); mean baseline ISI scores were 18·4 (SD 3·7) and 19·4 (SD 4·1) respectively. At week 33, 48 (92%) in the FtF CBT-I group and 41 (85%) in the dCBT-I group completed the ISI; the mean scores were 8·9 (SD 6·0) and 12·3 (SD 6·9) respectively. There was a significant time effect for both interventions (p<0·001); and the mean difference in ISI at week 33 was -2·8 (95% CI: -4·8 to -0·8; p=0·007). No significant differences were found on secondary outcomes. Interpretation: In a clinical sample, individual FtF CBT-I was superior to dCBT-I in reducing insomnia severity; however, both were associated with significant reductions in insomnia. These findings highlight the need for more clinical research to clarify the optimal application, dissemination, and implementation of dCBT-I. Trial Registration: ClinicalTrials.gov NCT02044263. Funding Statement: St. Olavs Hospital and SOVno. Declaration of Interests: Havard Kallestad, Jan Scott, Oystein Vedaa, Daniel Vethe, Gunnar Morken, Stian Lydersen, Tore C. Stiles, Borge Sivertsen, and Knut Langsrud: Declare no known conflicts of interest in relation to this research project and the submitted manuscript. Ethics Approval Statement: The protocol was approved by the Regional Ethical Committee of South-East Norway (Reference: 2013/1836).

Poor Sleep Quality's Association With Soccer Injuries: Preliminary Data.

To investigate the relationship between sleep quality and quantity and injuries in elite soccer players and to compare sleep-wake variables and injury characteristics. The current investigation was a prospective cohort study of 23 elite male soccer players competing for 2 teams over 6 mo in the highest-level Brazilian competition. The players' sleep behavior was monitored for 10 d in the preseason using self-reporting sleep diaries and wrist activity monitors to determine sleep duration and quality. Furthermore, injuries were recorded by the respective club's medical teams into a specific database. Details of injuries recorded included the type, location, and severity of each injury. The results were expressed as descriptive statistics, and the significance level was set at 5%. The Mann-Whitney U test was performed to compare the sleep variables between groups. Spearman correlation coefficient and linear-regression analysis were used. The results indicated a moderate negative correlation between sleep efficiency and particular injury characteristics, including absence time, injury severity, and amount of injuries. The linear-regression analysis indicated that 44% of the total variance in the number of injuries can be explained by sleep efficiency, 24% of the total variance in the absence time after injury (days) can be explained by sleep efficiency, and 47% of the total variance in the injury severity can be explained by sleep efficiency. Soccer players who exhibit lower sleep quality or nonrestorative sleep show associations with increased number and severity of musculoskeletal injuries.

Slovenian adaptation of the Morningness-Eveningness-Stability Scales improved (MESSi)

ABSTRACTCircadian preference can be measured by a set of questionnaires. While accepting the biological correlates as a good convergent criterion, researchers criticized currently used questionnaires because of their design, weighted number of items, unbalanced scoring or uneven Likert scales. This led to the development of a composite questionnaire, the Morningness-Eveningness-Stability-Scales improved (MESSi). The MESSi contains three constructs: morning affect (MA), eveningness (EV) and stability/distinctness (DI). The aim of this study was a preliminary assessment of a Slovenian translation of the MESSi. Students of five different study programs from the University of Ljubljana, Faculty of Education, participated in the study (N = 275). The scales fit to a three-factor solution, based on exploratory and confirmatory factor analysis. Cronbach’s α were 0.82 (MA), 0.85 (EV), and 0.69 (DI). After allowing covariances (loading onto the same factor) the model fit was good (RMSEA = 0.055). Nearly all sleep-wake variables were correlated with MA and EV in the expected direction. As a conclusion, we can propose to use the MESSi also in Slovenia.

Correlates of disrupted sleep–wake variables in patients with advanced cancer

ObjectivesHigh rates of sleep difficulties have been found in patients with advanced cancer. However, not much is known about factors that are associated with sleep impairments in this population and...

Shortening of sleep length and delayed mid-sleep on free days are the characteristic features of predominantly morning active population of Indian teenagers

We studied patterns in the distribution of chronotype and sleep–wake behavior in a randomly chosen sample population of Indian teenagers consisting 965 school-going children. All of them voluntarily responded on two structured inventories, namely truncated version of the morningness–eveningness questionnaire (MEQ) to assess chronotype and the Munich Chronotype Questionnaire (MCTQ) to determine sleep–wake variables on both work and free days. The results revealed that a majority of teens were predominantly morning active (59%), about 33% were intermediate, whereas only 8% were evening type. The mid-sleep on free days (MSF) in most of the subjects was 1 h delayed compared to those on work days. The MSF in adolescent was identified as the primary predictor of social jetlag. The average sleep duration was recorded to be less than 7 h on both school and free days. The evening chronotype teenagers were significantly sleeping less with more social jetlag and delayed mid-sleep than morning or neither type. This study gave an insight on the prevalence of lark chronotype and shorter sleep among Indian teenagers.

Sleep-wake functions and quality of life in patients with subthalamic deep brain stimulation for Parkinson's disease.

ObjectivesSleep-wake disturbances (SWD) are frequent in Parkinson’s disease (PD). The effect of deep brain stimulation (DBS) on SWD is poorly known. In this study we examined the subjective and objective sleep-wake profile and the quality of life (QoL) of PD patients in the context of subthalamic DBS.Patients and methodsWe retrospectively analyzed data from PD patients and candidates for DBS in the nucleus suthalamicus (STN). Pre-DBS, sleep-wake assessments included subjective and objective (polysomnography, vigilance tests and actigraphy) measures. Post-DBS, subjective measures were collected. QoL was assessed using the Parkinson’s Disease Questionnaire (PDQ-39) and the RAND SF-36-item Health Survey (RAND SF-36).ResultsData from 74 PD patients (62% male, mean age 62.2 years, SD = 8.9) with a mean UPDRS-III (OFF) of 34.2 (SD = 14.8) and 11.8 (SD = 4.5) years under PD treatment were analyzed. Pre-DBS, daytime sleepiness, apathy, fatigue and depressive symptoms were present in 49%, 34%, 38% and 25% of patients respectively but not always as co-occurring symptoms. Sleep-wake disturbances were significantly correlated with QoL scores. One year after STN DBS, motor signs, QoL and sleepiness improved but apathy worsened. Changes in QoL were associated with changes in sleepiness and apathy but baseline sleep-wake functions were not predictive of STN DBS outcome.ConclusionIn PD patients presenting for STN DBS, subjective and objective sleep-wake disturbances are common and have a negative impact on QoL before and after neurosurgery. Given the current preliminary evidence, prospective observational studies assessing subjective and objective sleep-wake variables prior to and after DBS are needed.

Abnormalities in the 24-hour rhythm of skin temperature in cirrhosis: Sleep-wake and general clinical implications.

Sleep preparation/onset are associated with peripheral vasodilatation and a decrease in body temperature. The hyperdynamic syndrome exhibited by patients with cirrhosis may impinge on sleep preparation, thus contributing to their difficulties falling asleep. The aim of this study was the assessment of skin temperature, in relation to sleep-wake patterns, in patients with cirrhosis. Fifty-three subjects were initially recruited, and 46 completed the study. Of the final 46, 12 were outpatients with cirrhosis, 13 inpatients with cirrhosis, 11 inpatients without cirrhosis and 10 healthy volunteers. All underwent baseline sleep-wake evaluation and blood sampling for inflammatory markers and morning melatonin levels. Distal/proximal skin temperature and their gradient (DPG) were recorded for 24hours by a wireless device. Over this period subjects kept a sleep-wake diary. Inpatients with cirrhosis slept significantly less well than the other groups. Inpatients and outpatients with cirrhosis had higher proximal temperature and blunted rhythmicity compared to the other groups. Inpatients with/without cirrhosis had higher distal temperature values and blunted rhythmicity compared to the other groups. Inpatients and outpatients with cirrhosis had significantly lower DPG values compared to the other groups, and DPG reached near-zero values several hours later. Significant correlations were observed between temperature and sleep-wake variables and inflammatory markers. Alterations of distal/proximal skin temperature, their gradient and their time-course were observed in patients with cirrhosis, which may contribute to their sleep disturbances.

Relationship between Cognitive and Sleep-wake Variables in Asymptomatic Offspring of Patients with Late-onset Alzheimer's Disease.

Early neuropathological changes characteristic of late-onset Alzheimer’s disease (LOAD) involve brain stem and limbic structures that regulate neurovegetative functions, including sleep–wake rhythm. Indeed, sleep pattern is an emerging biomarker and a potential pathophysiological mechanism in LOAD. We hypothesized that cognitively asymptomatic, middle-aged offspring of patients with LOAD (O-LOAD) would display a series of circadian rhythm abnormalities prior to the onset of objective cognitive alterations. We tested 31 children of patients with LOAD (O-LOAD) and 19 healthy individuals without family history of Alzheimer’s disease (control subjects, CS) with basic tests of cognitive function, as well as actigraphy measures of sleep–wake rhythm, cardiac autonomic function, and bodily temperature. Unexpectedly, O-LOAD displayed subtle but significant deficits in verbal episodic memory (Rey Auditory Verbal Learning Test delayed recall 10.6 ± 0.4 vs. 8.6 ± 0.6, t = 4.97, df = 49, p < 0.01) and language (Weschler’s vocabulary 51.4 ± 1.3 vs. 44.3 ± 1.5, t = 2.49, df = 49, p < 0.001) compared to CS, even though all participants had results within the clinically normal range. O-LOAD showed a phase-delayed rhythm of body temperature (2.56 ± 0.47 h vs. 3.8 ± 0.26 h, t = 2.48, df = 40, p = 0.031). Cognitive performance in O-LOAD was associated with a series of cardiac autonomic sleep–wake variables; specifically indicators of greater sympathetic activity at night were related to poorer cognition. The present results suggest sleep pattern deserves further study as a potential neurobiological signature in LOAD, even in middle-aged, at risk individuals.

Abnormalities in Skin Temperature and its 24-Hour Rhythm in Patients with Cirrhosis: Sleep-Wake and General Clinical Implications

Background and aims: Sleep preparation/onset are associated with peripheral vasodilatation and a decrease in body temperature. It is possible that the hyperdynamic syndrome exhibited by patients with cirrhosis may impinge on sleep preparation mechanisms, thus contributing to the difficulties falling asleep exhibited by these patients. The aim of this study was the assessment of skin temperature/their 24-hour rhythm in patients with cirrhosis of varying severity, in relation to sleep-wake patterns. Methods: Twelve outpatients with cirrhosis (CO), 13 inpatients with cirrhosis (CI), 11 inpatients without cirrhosis (NCI) and 10 healthy volunteers were recruited. All underwent baseline sleep-wake evaluation (sleep quality, diurnal preference, daytime sleepiness) and bleeding for inflammatory markers and morning melatonin levels. Proximal/distal skin temperature and their gradient (DPG) were recorded for 24 hours by a wireless device (iButton) and over this period subjects were asked to keep a sleep-wake diary. Results: CI slept significantly less well than all other groups. CI/CO had higher baseline proximal temperature and blunted rhythmicity compared to the other groups. CI/NCI had higher baseline distal temperature and blunted rhythmicity compared to the other groups. CI/CO had significantly lower DPG values compared to the other groups, and DPG reached near-zero values several hours later. Significant correlations were observed between temperature and sleep-wake variables (minimum proximal temperature vs. sleep latency: r = 0.50, P < 0.05) and also between temperature and inflammatory markers/melatonin [minimum proximal temperature vs. C reactive protein: r = 0.42, P < 0.05]. Conclusions: Alterations of distal/proximal skin temperature, their gradient and their time-course were observed in patients with cirrhosis. These may contribute to the sleep disturbances exhibited by these patients. The authors have none to declare.

What predicts a positive response to acupuncture? A secondary analysis of three randomised controlled trials of insomnia.

Few studies have investigated the predictors of the specific and non-specific effects of acupuncture. The aim of this secondary analysis was to determine patient characteristics that may predict a better treatment response to acupuncture for insomnia. We pooled the data of three randomised, double-blind, placebo-controlled trials of acupuncture for insomnia to examine sociodemographic variables, clinical characteristics, baseline sleep-wake variables, and treatment expectancy in relation to acupuncture response. Subjects with an improvement in insomnia severity index (ISI) scores of ≥8 points from baseline to 1 week post-treatment were classified as responders. Factors were compared between responders and non-responders, and also by univariate and multivariate logistic regression analysis. A total of 116 subjects who received traditional needle acupuncture were included, of which 37 (31.9%) were classified as responders. Acupuncture responders had a higher educational level (p<0.01) and higher baseline ISI score (p<0.05), compared to non-responders. In the multivariate logistic regression analysis, only the number of years spent in full-time education remained significant as a predictor of treatment response (OR 1.21, 95% CI 1.06 to 1.38, p<0.01). Consistent with previous studies, our data suggest that the response to acupuncture is difficult to predict. Although the predictive power of educational level is weak overall, our findings provide potentially valuable information that could be built upon in further research (including a larger sample size), and may help to inform patient selection for the treatment of chronic insomnia with acupuncture in the future. ClinicalTrials.gov: #NCT00839592; Results, #NCT00838994; Results, and #NCT01707706; Results.

Parallel recovery of consciousness and sleep in acute traumatic brain injury.

To investigate whether the progressive recuperation of consciousness was associated with the reconsolidation of sleep and wake states in hospitalized patients with acute traumatic brain injury (TBI). This study comprised 30 hospitalized patients (age 29.1 ± 13.5 years) in the acute phase of moderate or severe TBI. Testing started 21.0 ± 13.7 days postinjury. Consciousness level and cognitive functioning were assessed daily with the Rancho Los Amigos scale of cognitive functioning (RLA). Sleep and wake cycle characteristics were estimated with continuous wrist actigraphy. Mixed model analyses were performed on 233 days with the RLA (fixed effect) and sleep-wake variables (random effects). Linear contrast analyses were performed in order to verify if consolidation of the sleep and wake states improved linearly with increasing RLA score. Associations were found between scores on the consciousness/cognitive functioning scale and measures of sleep-wake cycle consolidation (p < 0.001), nighttime sleep duration (p = 0.018), and nighttime fragmentation index (p < 0.001). These associations showed strong linear relationships (p < 0.01 for all), revealing that consciousness and cognition improved in parallel with sleep-wake quality. Consolidated 24-hour sleep-wake cycle occurred when patients were able to give context-appropriate, goal-directed responses. Our results showed that when the brain has not sufficiently recovered a certain level of consciousness, it is also unable to generate a 24-hour sleep-wake cycle and consolidated nighttime sleep. This study contributes to elucidating the pathophysiology of severe sleep-wake cycle alterations in the acute phase of moderate to severe TBI.

Don't worry, sleep well: predictors of sleep loss over worry

In this study, our aim was to explore the relationship between sleep quality/quantity, chronotype, pre-sleep arousal, arousability, stress, coping, neuroticism, extraversion, mood/affect, perceived health and sleep loss due to worry in college students. A total of 713 students (mean age 19.29 ± 1.256 years) completed a set of questionnaires that assessed sleep loss over worry (item from the General Health Questionnaire), other sleep–wake aspects (e.g., habitual sleep duration, sleep needs, sleep depth, subjective sleep quality, sleep latency, night awakenings, daytime sleepiness, sleep flexibility, sleep reactivity to stress), pre-sleep arousal (cognitive/somatic arousal), arousability, coping, neuroticism, extraversion, perceived physical/mental health, academic stress and positive/negative affect. Sleep disturbance due to worry was reported by 40.6 % of female and 19.2 % of male students. It was significantly correlated with perceived health and the majority of sleep–wake variables. Almost all correlations between the psychological traits under study and sleep loss over worry were significant. Results from the stepwise regression analyses, however, showed that only cognitive arousal (β = .353; p < .001), perceived academic stress (β = .129; p < .01), arousability (β = .127; p < .01), worry tendency (β = .153; p < .001), gender (β = .118; p < .01) and perceived physical health (β = −.093; p < .01) were significant predictors of sleep loss over worry. Together, these variables accounted for 40.3 % of the total variance in sleep disturbance due to worry. Our findings suggest that cognitive arousal, academic stress, arousability, tendency to worry, gender and perceived physical health may be important determinants of sleep loss over worry. These results may have important implications for prevention and intervention to improve sleep quality in young adults.