First-night effect in normal subjects and psychiatric inpatients

Oral appliance therapy versus nasal continuous positive airway pressure in obstructive sleep apnoea syndrome: a randomised, placebo-controlled trial on self-reported symptoms of common sleep disorders and sleep-related problems

Obstructive sleep apnoea syndrome (OSAS) is associated with several sleep disorders and sleep-related problems. Therefore, the aim of this study was to compare the effects of a mandibular advancement device (MAD) with those of nasal continuous positive airway pressure (nCPAP) on self-reported symptoms of common sleep disorders and sleep-related problems in mild and moderate OSAS patients. In this randomised placebo-controlled trial, sixty-four OSAS patients (52·0 ± 9·6 years) were randomly assigned to an MAD, nCPAP or an intra-oral placebo appliance in a parallel design. All participants filled out the validated Dutch Sleep Disorders Questionnaire (SDQ) twice: one before treatment and one after six months of treatment. With 88 questions, thirteen scales were constructed, representing common sleep disorders and sleep-related problems. Linear mixed model analyses were performed to study differences between the groups for the different SDQ scales over time. The MAD group showed significant improvements over time in symptoms corresponding with 'insomnia', 'excessive daytime sleepiness', 'psychiatric sleep disorder', 'periodic limb movements', 'sleep apnoea', 'sleep paralysis', 'daytime dysfunction', 'hypnagogic hallucinations/dreaming', 'restless sleep', 'negative conditioning' and 'automatic behaviour' (range of P values: 0·000-0·014). These improvements in symptoms were, however, not significantly different from the improvements in symptoms observed in the nCPAP and placebo groups (range of P values: 0·090-0·897). It can be concluded that there is no significant difference between MAD and nCPAP in their positive effects on self-reported symptoms of common sleep disorders and sleep-related problems in mild and moderate OSAS patients. These beneficial effects may be a result of placebo effects.

Effects of Short-Term Acclimatization at the Summit of Mt. Fuji (3776 m) on Sleep Efficacy, Cardiovascular Responses, and Ventilatory Responses

Horiuchi, Masahiro, Shiro Oda, Tadashi Uno, Junko Endo, Yoko Handa, and Yoshiyuki Fukuoka. Effects of short-term acclimatization at the summit of Mt. Fuji (3776 m) on sleep efficacy, cardiovascular responses, and ventilatory responses. High Alt Med Biol. 18:171-178, 2017.-We investigated the effects of a short period of acclimatization, at 3776 m on Mt. Fuji, on sleep parameters and related physiological responses. Physiological responses were assessed in seven healthy lowlander men during both daytime and sleep while at sea level (SL), as well as for three consecutive nights at high altitude (HA; 3776 m, day 1 [D1], D2, D3, and morning only of D4). Blood pressure variables, heart rate (HR), pulmonary ventilation (V_E), and breathing frequency (Bf) progressively increased each day, with significant differences between SL and HA (p < 0.05, respectively). In contrast, end-tidal PCO₂ (P_ETCO₂) progressively decreased each day with statistical differences between SL and D3 at HA (p < 0.05). During sleep at HA, mean arterial pressure (MAP) was stable, whereas it decreased during sleep at SL. Sleep efficacy, which was assessed by actigraphy, was linearly impaired with statistical differences between SL and D3 (p < 0.05). These impairments in sleep efficacy at HA were associated with higher MAP and HR, as well as lower Bf and P_ETCO₂ during the daytime (pooled data, p < 0.05, respectively). These results suggest that hypoxia-induced cardiovascular and ventilatory responses may be crucial contributors to changes in sleep efficacy at HA.

Sleep disturbances in irritable bowel syndrome: a systematic review

BACKGROUND

Sleep disturbances are well-documented among persons with irritable bowel syndrome (IBS). Difficulty in falling asleep, shorter sleep time, frequent arousal and awakenings, or non-restorative sleep are the most common manifestations. Sleep disturbances are also related to a higher risk of having IBS. Some researchers have provided evidence of a positive association between poorer subjective sleep quality and increased severity and frequency in gastrointestinal (GI) symptoms in those with IBS. However, findings from studies using objective sleep and activity measures, such as polysomnography and actigraphy, are inconclusive.

PURPOSE

This systematic review of the literature between 1990 and 2015 evaluates the evidence of sleep disturbances in adults with IBS and their relationship with GI symptoms.

Sensing Technologies for Autism Spectrum Disorder Screening and Intervention

This paper reviews the state-of-the-art in sensing technologies that are relevant for Autism Spectrum Disorder (ASD) screening and therapy. This disorder is characterized by difficulties in social communication, social interactions, and repetitive behaviors. It is diagnosed during the first three years of life. Early and intensive interventions have been shown to improve the developmental trajectory of the affected children. The earlier the diagnosis, the sooner the intervention therapy can begin, thus, making early diagnosis an important research goal. Technological innovations have tremendous potential to assist with early diagnosis and improve intervention programs. The need for careful and methodological evaluation of such emerging technologies becomes important in order to assist not only the therapists and clinicians in their selection of suitable tools, but to also guide the developers of the technologies in improving hardware and software. In this paper, we survey the literatures on sensing technologies for ASD and we categorize them into eye trackers, movement trackers, electrodermal activity monitors, tactile sensors, vocal prosody and speech detectors, and sleep quality assessment devices. We assess their effectiveness and study their limitations. We also examine the challenges faced by this growing field that need to be addressed before these technologies can perform up to their theoretical potential.

Reduced Rapid Eye Movement Density in Parkinson Disease: A Polysomnography-Based Case-Control Study

STUDY OBJECTIVES

To explore rapid eye movement density (RD) in patients with idiopathic Parkinson disease (IPD) and to investigate its usefulness as surrogate marker of excessive daytime sleepiness, a frequent complaint in IPD patients.

METHODS

Retrospective polysomnography study on 81 subjects without dementia: 29 patients with early stage IPD (disease duration ≤ 3 y), 21 patients with middle- stage IPD (disease duration > 3 and < 8 y) and 31 healthy controls (HC). Rapid eye movement (REM) sleep was defined as any REM episode with > 3 min of continuous REM sleep. RD was defined as number of ocular movements per minute of REM sleep. Patients with early stage IPD and HC fulfilled the PD-specific sleepiness questionnaires Parkinson's Disease Sleep Scale (PDSS) and the Nonmotor Symptoms Questionnaire for Parkinson's disease (NMSQuest).

RESULTS

RD was lower in patients with IPD than in HC. The difference was most significant between patients with middle stage IPD and HC (P = 0.001), and most prominent for the third REM episode, again when comparing patients with middle stage IPD and HC (P = 0.03). RD was independent from sex, age, and other sleep parameters. In early stage IPD, RD correlated with the PDSS score (r = -0.63, P = 0.001) and the sleep-related questions of the NMSQuest score (r = 0.48, P = 0.017).

CONCLUSIONS

REM density is reduced in patients with IPD and correlates with subjective scores on sleep impairment. As an indicator of persistent high sleep pressure, reduced RD in IPD is eligible as a biomarker of excessive daytime sleepiness in IPD. It possibly reflects direct involvement of the brainstem REM generation sites by the disease process. RD is a promising new tool for sleep research in IPD.

Assessment for the possibility of a first night effect for wrist actigraphy in adolescents

OBJECTIVES

Evidence of a 'first night effect' has been documented for polysomnography. The possibility of this has not been previously assessed in wrist actigraphy, yet may have important implications for the study design of future sleep research. We sought to examine potential evidence of a 'first night effect' for wrist actigraphy in adolescents across weekdays and weekend nights for multiple sleep outcomes.

DESIGN

3-year prospective cohort study (Midlands Adolescent Schools Sleep Education Study).

SETTING

8 secondary schools in the Midlands region of the UK.

PARTICIPANTS

Adolescents (aged 11-13 years at baseline) were recruited to the study and were requested to wear a wrist actigraph for 7 consecutive days/nights at baseline and then annually for 2 years during the second term of the academic year.

PRIMARY OUTCOME MEASURES

We compared multiple sleep outcomes (total sleep time, wake after sleep onset, sleep efficiency, sleep onset latency, number of awakenings, length of awakenings, sleep onset time) when the device was worn on a weekday and weekend and compared these to other nights to identify possible evidence of a 'first night effect' for wrist actigraphy.

RESULTS

No significant differences were found between any sleep outcomes when the first night of wrist actigraphy was on a weekday compared with other weekdays. When the first night was measured on a weekend (Friday), average total sleep time was significantly greater (486±5 min) compared with the second night (Saturday; 469±6 min), p=0.01.

CONCLUSIONS

We found no evidence to support a 'first night effect' for wrist actigraphy in our adolescent sample. The first night of actigraphy data should not be disregarded in future studies that deploy this technique to measure sleep over prolonged time periods.

Increasing Explicit Sequence Knowledge by Odor Cueing during Sleep in Men but not Women

Sleep consolidates newly acquired memories. Beyond stabilizing memories, sleep is thought to reorganize memory representations such that invariant structures, statistical regularities and even new explicit knowledge are extracted. Whereas increasing evidence suggests that the stabilization of memories during sleep can be facilitated by cueing with learning-associated stimuli, the effect of cueing on memory reorganization is less well understood. Here we asked whether olfactory cueing during sleep enhances the generation of explicit knowledge about an implicitly learned procedural memory task. Subjects were trained on a serial reaction time task (SRTT) containing a hidden 12-element sequence in the presence of an odor. During subsequent sleep, half of the subjects were re-exposed to the odor during periods of slow wave sleep (SWS), while the other half received odorless vehicle. In the next morning, subjects were tested on their explicit knowledge about the underlying sequence in a free recall test and a generation task. Although odor cueing did not significantly affect overall explicit knowledge, differential effects were evident when analyzing male and female subjects separately. Explicit sequence knowledge, both in free recall and the generation task, was enhanced by odor cueing in men, whereas women showed no cueing effect. Procedural skill in the SRTT was not affected by cueing, neither in men nor in women. These findings suggest that olfactory memory reactivation can increase explicit knowledge about implicitly learned information, but only in men. Hormonal differences due to menstrual cycle phase and/or hormonal contraceptives might explain the lacking effect in women.

Acute stress alters autonomic modulation during sleep in women approaching menopause

Hot flashes, hormones, and psychosocial factors contribute to insomnia risk in the context of the menopausal transition. Stress is a well-recognized factor implicated in the pathophysiology of insomnia; however the impact of stress on sleep and sleep-related processes in perimenopausal women remains largely unknown. We investigated the effect of an acute experimental stress (impending Trier Social Stress Task in the morning) on pre-sleep measures of cortisol and autonomic arousal in perimenopausal women with and without insomnia that developed in the context of the menopausal transition. In addition, we assessed the macro- and micro-structure of sleep and autonomic functioning during sleep. Following adaptation to the laboratory, twenty two women with (age: 50.4 ± 3.2 years) and eighteen women without (age: 48.5 ± 2.3 years) insomnia had two randomized in-lab overnight recordings: baseline and stress nights. Anticipation of the task resulted in higher pre-sleep salivary cortisol levels and perceived tension, faster heart rate and lower vagal activity, based on heart rate variability measures, in both groups of women. The effect of the stress manipulation on the autonomic nervous system extended into the first 4 h of the night in both groups. However, vagal tone recovered 4-6 h into the stress night in controls but not in the insomnia group. Sleep macrostructure was largely unaltered by the stress, apart from a delayed latency to REM sleep in both groups. Quantitative analysis of non-rapid eye movement sleep microstructure revealed greater electroencephalographic (EEG) power in the beta1 range (15-≤23 Hz), reflecting greater EEG arousal during sleep, on the stress night compared to baseline, in the insomnia group. Hot flash frequency remained similar on both nights for both groups. These results show that pre-sleep stress impacts autonomic nervous system functioning before and during sleep in perimenopausal women with and without insomnia. Findings also indicate that women with insomnia had increased EEG arousal and lacked recovery in vagal activity across the stress night suggesting a greater sensitivity to stress in this group.

Sleep Irregularity in the Previous Week Influences the First-Night Effect in Polysomnographic Studies

OBJECTIVE

The first-night effect is a well-known phenomenon resulting from an individual's maladaptation to the unfamiliar environment of a sleep laboratory. However, there have been no direct reports of the effect of previous sleep patterns on the first-night effect. We aimed to investigate the effect the previous week's sleep pattern on the first-night effect.

METHODS

Twenty-four young, healthy, male participants completed the study procedure. During one week prior to study, the participants kept sleep diaries and wore actigraphs to identify sleep-wake pattern. Two consecutive nights of polysomnography were conducted after that. Wilcoxon signed-rank tests were applied to compare sleep variables of the two nights. Variance (standard deviation) of sleep onset time during the previous week was used as an index of irregularity. A Kendall's ranked correlation analysis and a linear regression test were applied to detect correlation between sleep irregularity and the first-night effect measured by polysomnography.

RESULTS

There were significant differences in the values of sleep efficiency (p=0.011) and wake after sleep onset (WASO) (p=0.006) between the two nights. Sleep efficiency was lower and WASO was higher on the first night as compared to the second night. Sleep irregularity in the previous week was negatively correlated with sleep efficiency (p<0.001) of the first night, but was not significantly correlated with any other sleep parameters.

CONCLUSION

We replicated the existence of the first-night effect commonly observed in sleep studies. Sleep irregularity in the previous week may influence the first-night effect in polysomnographic studies.

Assessing the daily stability of the cortisol awakening response in a controlled environment

Background

Levels of cortisol, the end product of the hypothalamic-pituitary-adrenal (HPA) axis, display a sharp increase immediately upon awakening, known as the cortisol awakening response (CAR). The daily stability of the CAR is potentially influenced by a range of methodological factors, including light exposure, participant adherence, sleep duration and nocturnal awakenings, making inferences about variations in the CAR difficult. The aim of the present study was to determine the daily stability of multiple measurement indices of the CAR in a highly-controlled sleep laboratory environment. A secondary aim was to examine the association between objective sleep continuity and sleep architecture, and the CAR.

Methods

The CAR was assessed in 15 healthy normal sleepers (seven male, eight female, M_age = 23.67 ± 3.49 years) on three consecutive weekday mornings. Sleep was measured objectively using polysomnography. Saliva samples were obtained at awakening, +15, +30, +45 and +60 min, from which multiple CAR measurement indices were derived: cortisol levels at each time point, awakening cortisol levels, the mean increase in cortisol levels (MnInc) and total cortisol secretion during the measurement period. Morning 2 and Morning 3 awakening cortisol levels, MnInc and total cortisol secretion were compared and the relationship between Night 1 and Night 2 objective measures of sleep continuity and architecture, and the subsequent CAR, was also assessed.

Results

There were no differences in cortisol levels at each time point, or total cortisol secretion during the CAR period, between Morning 2 and Morning 3. Awakening cortisol levels were lower, and the MnInc was higher, on Morning 3. Morning 2 and Morning 3 awakening levels (r = 0.77) and total cortisol secretion (r = 0.82), but not the magnitude of increase, were positively associated.

Conclusions

The stability of the CAR profile and total cortisol secretion, but not awakening cortisol levels or the magnitude of increase, was demonstrated across two consecutive mornings of measurement in a highly-controlled environment. Awakening cortisol levels, and the magnitude of increase, may be sensitive to differences in daily activities.

Electronic supplementary material

The online version of this article (doi:10.1186/s40359-016-0107-6) contains supplementary material, which is available to authorized users.

Discrepancies Between Self-Reported Usual Sleep Duration and Objective Measures of Total Sleep Time in Treatment-Seeking Overweight and Obese Individuals

To examine the agreement between actigraphy-estimated and self-reported sleep duration in obese individuals, we had 63 treatment seeking overweight/obese participants complete the Pittsburgh Sleep Quality Index (PSQI) and report sleep duration for weekends and weekdays, and compared their reports to 7 days of actigraphy. Actigraph total sleep time correlated r = .20-.31 with self-report and the absolute discrepancy averaged 51-54 minutes. Only 20 of the 32 subjects (62.5%) classified as short sleepers (<7 hours/night) by actigraphy were similarly classified by self-report. Poor sleep quality was associated with greater absolute discrepancy between actigraphy and self-report. The weak correlations between self-report and actigraph should be considered in future efforts to increase sleep duration to promote weight loss in obese individuals.

Rapid eye movement-sleep is reduced in patients with acute uncomplicated diverticulitis-an observational study

Introduction. Sleep disturbances are commonly found in patients in the postoperative period. Sleep disturbances may give rise to several complications including cardiopulmonary instability, transient cognitive dysfunction and prolonged convalescence. Many factors including host inflammatory responses are believed to cause postoperative sleep disturbances, as inflammatory responses can alter sleep architecture through cytokine-brain interactions. Our aim was to investigate alteration of sleep architecture during acute infection and its relationships to inflammation and clinical symptoms. Materials & Methods. In this observational study, we included patients with acute uncomplicated diverticulitis as a model to investigate the isolated effects of inflammatory responses on sleep. Eleven patients completed the study. Patients were admitted and treated with antibiotics for two nights, during which study endpoints were measured by polysomnography recordings, self-reported discomfort scores and blood samples of cytokines. One month later, the patients, who now were in complete remission, were readmitted and the endpoints were re-measured (the baseline values). Results. Total sleep time was reduced 4% and 7% the first (p = 0.006) and second (p = 0.014) nights of diverticulitis, compared to baseline, respectively. The rapid eye movement sleep was reduced 33% the first night (p = 0.016), compared to baseline. Moreover, plasma IL-6 levels were correlated to non-rapid eye movement sleep, rapid eye movement sleep and fatigue. Conclusion. Total sleep time and rapid eye movement sleep were reduced during nights with active diverticulitis and correlated with markers of inflammation.

Patients with primary insomnia in the sleep laboratory: do they present with typical nights of sleep?

The validity of sleep laboratory investigations in patients with insomnia is important for researchers and clinicians. The objective of this study was to examine the first-night effect and the reverse first-night effect in patients with chronic primary insomnia compared with good sleeper controls. A retrospective comparison of a well-characterised sample of 50 patients with primary insomnia and 50 good sleeper controls was conducted with respect to 2 nights of polysomnography, and subjective sleep parameters in the sleep laboratory and the home setting. When comparing the first and second sleep laboratory night, a significant first-night effect was observed across both groups in the great majority of the investigated polysomnographic and subjective variables. However, patients with primary insomnia and good sleeper controls did not differ with respect to this effect. Regarding the comparison between the sleep laboratory nights and the home setting, unlike good sleeper controls, patients with primary insomnia reported an increased subjective sleep efficiency on both nights (in part due to a reduced bed time) and an increased subjective total sleep time on the second night. These results suggest that even the second sleep laboratory night does not necessarily provide clinicians and researchers with a representative insight into the sleep perception of patients with primary insomnia. Future studies should investigate whether these findings also hold for other patient populations.

Effect of prone positioning in mild to moderate obstructive sleep apnea syndrome

BACKGROUND

Sleeping in prone position could be effective in the management of obstructive sleep apnea (OSA) syndrome by reducing the gravity effect on the upper airway and hence collapsibility. Effect of pure prone positioning (PPP) treatment was investigated in mild to moderate OSA.

PATIENTS AND METHODS

Twenty-nine mild to moderate OSA patients (17 males, 12 females) who gave informed consent were tested with polysomnography at diagnostic and PPP nights. PPP device consisted of a pillow mounted on a table with a hole in the middle keeping the neck 180° extended in prone position. Mean ± SD of age and AHI were 48.4 ± 10.6 and 15.5 ± 6.2, respectively. Patients did not have abdominal and/or truncalobesity, or any condition that could interfere with prone sleeping.

RESULTS

AHI (mean difference: PPP treatment - diagnostic night: -5.2/h, 95% confidence interval [CI]: -0.1/h to -10.3/h, p = 0.04) and sleep oxygen saturation below 90% (mean difference: -1.80%, 95% CI: -0.22% to -3.37%, p = 0.02) and sleep efficiency (81.0 ± 21.2% and 88.1 ± 7.1 %, respectively, p = 0.02) were significantly lower in PPP than diagnostic night. Response to PPP treatment defined as AHI <5/h in the PPP night was observed in 15 (51.7%) patients, with a better rate in female than male patients (9/12 vs. 6/17, respectively, p = 0.03).

CONCLUSIONS

To our knowledge, this is the first study to examine the effect of prone positioning in the treatment of mild to moderate OSA. Application of PPP with a more comfortable design in a randomized clinical trial is required to investigate its long term effect in the treatment of mild to moderate OSA.

Objective and subjective components of the first-night effect in young nightmare sufferers and healthy participants

The first-night effect--marked differences between the first- and the second-night sleep spent in a laboratory--is a widely known phenomenon that accounts for the common practice of excluding the first-night sleep from any polysomnographic analysis. The extent to which the first-night effect is present in a participant, as well as its duration (1 or more nights), might have diagnostic value and should account for different protocols used for distinct patient groups. This study investigated the first-night effect on nightmare sufferers (NM; N = 12) and healthy controls (N = 15) using both objective (2-night-long polysomnography) and subjective (Groningen Sleep Quality Scale for the 2 nights spent in the laboratory and 1 regular night spent at home) methods. Differences were found in both the objective (sleep efficiency, wakefulness after sleep onset, sleep latency, Stage-1 duration, Stage-2 duration, slow-wave sleep duration, and REM duration) and subjective (self-rating) variables between the 2 nights and the 2 groups, with a more pronounced first-night effect in the case of the NM group. Furthermore, subjective sleep quality was strongly related to polysomnographic variables and did not differ among 1 regular night spent at home and the second night spent in the laboratory. The importance of these results is discussed from a diagnostic point of view.

Hyperinsulinemic response to oral glucose challenge in individuals with posttraumatic stress disorder

BACKGROUND

Posttraumatic stress disorder (PTSD) is associated with a 2-4 fold increased risk of developing Type 2 diabetes mellitus. However, detailed assessments of glucose metabolism and insulin secretion in a study designed to minimize confounders are lacking. Furthermore, few studies examine potential mechanisms involved. We analyzed data from a case-control study of medically healthy, medication-free adults to determine whether individuals with PTSD had abnormal glucose or insulin response to oral glucose tolerance test (OGTT) compared to controls. Secondarily, we assessed potential mediators such as sleep, cortisol and adiponectin.

METHODS

Data was analyzed from 92 age and gender-matched subjects (44 PTSD, 48 controls). Chronic PTSD was diagnosed using the Structured Clinical Interview for DSM-IV and Clinician Administered PTSD Scale. Subjects underwent 75-g OGTT, actigraphy and sleep diary (to quantify sleep duration), polysomnography (to assess slow wave sleep [SWS] and delta power), and overnight blood sampling (for cortisol and adiponectin).

RESULTS

At baseline, individuals with PTSD had mildly increased insulin levels (by 19%, compared to controls, p=0.048) that was mediated primarily by weight. In response to OGTT, the PTSD group had higher levels of insulin at 120 min (by 44%, p=0.03) and insulin AUC (by 43%, p=0.015) compared to controls, after adjusting for confounders. Glucose levels were similar in the two groups. Although self-reported sleep duration, SWS, and delta power differed between PTSD subjects and controls, they did not mediate the effects of PTSD status on insulin response.

CONCLUSION

In this case-control study, individuals with PTSD had a hyperinsulinemic response to oral glucose challenge compared to controls, suggestive of insulin resistance.

Management of sleep apnea without high pretest probability or with comorbidities by three nights of portable sleep monitoring

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) diagnosis using simplified methods such as portable sleep monitoring (PM) is only recommended in patients with a high pretest probability. The aim is to determine the diagnostic efficacy, consequent therapeutic decision-making, and costs of OSA diagnosis using polysomnography (PSG) versus three consecutive studies of PM in patients with mild to moderate suspicion of sleep apnea or with comorbidity that can mask OSA symptoms.

DESIGN AND SETTING

Randomized, blinded, crossover study of 3 nights of PM (3N-PM) versus PSG. The diagnostic efficacy was evaluated with receiver operating characteristic (ROC) curves. Therapeutic decisions to assess concordance between the two different approaches were performed by sleep physicians and respiratory physicians (staff and residents) using agreement level and kappa coefficient. The costs of each diagnostic strategy were considered.

PATIENTS AND RESULTS

Fifty-six patients were selected. Epworth Sleepiness Scale was 10.1 (5.3) points. Bland-Altman plot for apnea-hypopnea index (AHI) showed good agreement. ROC curves showed the best area under the curve in patients with PSG AHI ≥ 5 [0.955 (confidence interval = 0.862-0.993)]. For a PSG AHI ≥ 5, a PM AHI of 5 would effectively exclude and confirm OSA diagnosis. For a PSG AHI ≥ 15, a PM AHI ≥ 22 would confirm and PM AHI < 7 would exclude OSA. The best agreement of therapeutic decisions was achieved by the sleep medicine specialists (81.8%). The best cost-diagnostic efficacy was obtained by the 3N-PM.

CONCLUSIONS

Three consecutive nights of portable monitoring at home evaluated by a qualified sleep specialist is useful for the management of patients without high pretest probability of obstructive sleep apnea or with comorbidities.

CLINICAL TRIAL REGISTRATION

http://www.clinicaltrials.gov, registration number: NCT01820156.

CITATION

Guerrero A, Embid C, Isetta V, Farre R, Duran-Cantolla J, Parra O, Barbé F, Montserrat JM, Masa JF. Management of sleep apnea without high pretest probability or with comorbidities by three nights of portable sleep monitoring.

A seven day actigraphy-based study of rumination and sleep disturbance among young adults with depressive symptoms

OBJECTIVES

Trait ruminators exhibit significantly higher levels of sleep disturbance than those without this cognitive vulnerability. However, support for the sleep disruptive effects of state rumination, especially in the pre-sleep period, is rare, and hindered by methodological drawbacks such as self-report and single night assays of sleep. Finally, despite the pervasiveness of the ruminative response style among individuals with depression, the association between rumination and sleep disturbance has not been explored in this population. The present study employed a week-long daily sampling approach to examine the effects of naturally occurring pre-sleep rumination on self-reported and actigraphy-based sleep among individuals with high depressive symptomatology.

METHODS

Forty-two university students (19.6±3.2 yo;73.8% female), all of whom reported at least moderate levels of depressive symptoms, completed a short questionnaire after waking each morning for seven days. On this questionnaire, they self-reported sleep indices from the previous night and levels of engagement in pre-sleep rumination. Sleep was also monitored throughout this period via wrist actigraphy. Hierarchical-linear-modeling was used to examine the association between nightly rumination and sleep.

RESULTS

Nightly variations in pre-sleep rumination were predictive of significantly longer actigraphy- and diary-based sleep onset latency (SOL). Notably, a 1 SD increase on the pre-sleep rumination scale was associated with an approximately 7 minute increase in actigraphy-based SOL, even after controlling for baseline sleep disturbance and depressive symptoms.

CONCLUSIONS

These data offer compelling evidence for the impact of pre-sleep rumination on sleep onset, providing insight into one potential mechanism that triggers sleep disturbance among individuals with depressive symptoms.

Guidelines for the recording and evaluation of pharmaco-sleep studies in man: the International Pharmaco-EEG Society (IPEG)

The International Pharmaco-EEG Society (IPEG) presents guidelines summarising the requirements for the recording and computerised evaluation of pharmaco-sleep data in man. Over the past years, technical and data-processing methods have advanced steadily, thus enhancing data quality and expanding the palette of sleep assessment tools that can be used to investigate the activity of drugs on the central nervous system (CNS), determine the time course of effects and pharmacodynamic properties of novel therapeutics, hence enabling the study of the pharmacokinetic/pharmacodynamic relationship, and evaluate the CNS penetration or toxicity of compounds. However, despite the presence of robust guidelines on the scoring of polysomnography -recordings, a review of the literature reveals inconsistent -aspects in the operating procedures from one study to another. While this fact does not invalidate results, the lack of standardisation constitutes a regrettable shortcoming, especially in the context of drug development programmes. The present guidelines are intended to assist investigators, who are using pharmaco-sleep measures in clinical research, in an effort to provide clear and concise recommendations and thereby to standardise methodology and facilitate comparability of data across laboratories.

Ambulatory circadian monitoring (ACM) based on thermometry, motor activity and body position (TAP): a comparison with polysomnography

An integrated variable based on the combination of wrist Temperature, motor Activity and body Position (TAP) was previously developed at our laboratory to evaluate the functioning of the circadian system and sleep-wake rhythm under ambulatory conditions. However, the reliability of TAP needed to be validated with polysomnography (PSG). 22 subjects suffering from sleep disorders were monitored for one night with a temperature sensor (iButton), an actimeter (HOBO) and exploratory PSG. Mean waveforms, sensitivity (SE), specificity (SP), agreement rates (AR) and comparisons between TAP and sleep stages were studied. The TAP variable was optimized for SE, SP and AR with respect to each individual variable (SE: 92%; SP: 78%; AR: 86%). These results improved upon estimates previously published for actigraphy. Furthermore, TAP values tended to decrease as sleep depth increased, reaching the lowest point at phase 3. Finally, TAP estimates for sleep latency (SL: 37±9 min), total sleep time (TST: 367±13 min), sleep efficiency (SE: 86.8±1.9%) and number of awakenings (NA>5 min: 3.3±.4) were not significantly different from those obtained with PSG (SL: 29±4 min; SE: 89.9±1.8%; NA>5 min: 2.3±.4), despite the heterogeneity of the sleep pathologies monitored. The TAP variable is a novel measurement for evaluating circadian system status and sleep-wake rhythms with a level of reliability better to that of actigraphy. Furthermore, it allows the evaluation of a patient's sleep-wake rhythm in his/her normal home environment, and at a much lower cost than PSG. Future studies in specific pathologies would verify the relevance of TAP in those conditions.

Is there a first night effect on sleep bruxism? A sleep laboratory study

STUDY OBJECTIVES

Sleep bruxism (SB) is reported to vary in frequency over time. The aim of this study was to assess the first night effect on SB.

METHODS

A retrospective polysomnographic (PSG) analysis was performed of data from a sample of SB patients (12 females, 4 males; age range: 17-39 years) recorded in a sleep laboratory over 2 consecutive nights. Sleep parameters and jaw muscle activity variables (i.e., rhythmic masticatory muscle activity [RMMA]) for SB were quantified and compared between the 2 nights. Subjects were classified into groups according to severity of RMMA frequency, such as low frequency (2-4 episodes/h and/or < 25 bursts/h) and moderate-high frequency (≥ 4 episodes/h and ≥ 25 bursts/h).

RESULTS

Overall, no first night effects were found for most sleep variables. However, total sleep time, sleep efficiency, and stage transitions showed significant time and group interactions (repeated measures ANOVAs, p ≤ 0.05). The RMMA episode index did not differ between the 2 nights, whereas the second night showed significantly higher burst index, bruxism time index, and mean burst duration (repeated measure ANOVAs, p ≤ 0.05). Five patients of 8 in the low frequency group were classified into the moderate-high frequency group on the second night, whereas only one patient in the moderate-high frequency group moved to the low frequency group.

CONCLUSIONS

The results showed no overall first night effect on severity of RMMA frequency in young and healthy patients with SB. In clinical practice, one-night sleep recording may be sufficient for moderate-high frequency SB patients. However, low RMMA frequency in the first night could be confirmed by a second night based on the patient's medical and dental history.

Objectively measured sleep duration and hyperglycemia in pregnancy

OBJECTIVE

Our primary purpose was to assess the impact of objectively measured nighttime sleep duration on gestational glucose tolerance. We additionally examined associations of objectively measured daytime sleep duration and nap frequency on maternal glycemic control.

METHODS

Sixty-three urban, low-income, pregnant women wore wrist actigraphs for an average of 6 full days in mid-pregnancy prior to screening for hyperglycemia using the 1-h oral glucose tolerance test (OGTT). Correlations of nighttime and daytime sleep durations with 1-h OGTT values were analyzed. Multivariable logistic regression was used to evaluate independent associations between sleep parameters and hyperglycemia, defined as 1-h OGTT values ≥130 mg/dL.

RESULTS

Mean nighttime sleep duration was 6.9±0.9 h which was inversely correlated with 1-h OGTT values (r=-0.28, P=.03). Shorter nighttime sleep was associated with hyperglycemia, even after controlling for age and body mass index (adjusted odds ratio [OR], 0.2 [95% confidence interval {CI}, 0.1-0.8]). There were no associations of daytime sleep duration and nap frequency with 1-h OGTT values or hyperglycemia.

CONCLUSIONS

Using objective measures of maternal sleep time, we found that women with shorter nighttime sleep durations had an increased risk for gestational hyperglycemia. Larger prospective studies are needed to confirm our negative daytime sleep findings.

Nocturnal rapid eye movement sleep latency for identifying patients with narcolepsy/hypocretin deficiency

IMPORTANCE

Narcolepsy, a disorder associated with HLA-DQB1*06:02 and caused by hypocretin (orexin) deficiency, is diagnosed using the Multiple Sleep Latency Test (MSLT) following nocturnal polysomnography (NPSG). In many patients, a short rapid eye movement sleep latency (REML) during the NPSG is also observed but not used diagnostically.

OBJECTIVE

To determine diagnostic accuracy and clinical utility of nocturnal REML measures in narcolepsy/hypocretin deficiency.

DESIGN, SETTING, AND PARTICIPANTS

Observational study using receiver operating characteristic curves for NPSG REML and MSLT findings (sleep studies performed between May 1976 and September 2011 at university medical centers in the United States, China, Korea, and Europe) to determine optimal diagnostic cutoffs for narcolepsy/hypocretin deficiency compared with different samples: controls, patients with other sleep disorders, patients with other hypersomnias, and patients with narcolepsy with normal hypocretin levels. Increasingly stringent comparisons were made. In a first comparison, 516 age- and sex-matched patients with narcolepsy/hypocretin deficiency were selected from 1749 patients and compared with 516 controls. In a second comparison, 749 successive patients undergoing sleep evaluation for any sleep disorders (low pretest probability for narcolepsy) were compared within groups by final diagnosis of narcolepsy/hypocretin deficiency. In the third comparison, 254 patients with a high pretest probability of having narcolepsy were compared within group by their final diagnosis. Finally, 118 patients with narcolepsy/hypocretin deficiency were compared with 118 age- and sex-matched patients with a diagnosis of narcolepsy but with normal hypocretin levels.

MAIN OUTCOME AND MEASURES

Sensitivity and specificity of NPSG REML and MSLT as diagnostic tests for narcolepsy/hypocretin deficiency. This diagnosis was defined as narcolepsy associated with cataplexy plus HLA-DQB1*06:02 positivity (no cerebrospinal fluid hypocretin-1 results available) or narcolepsy with documented low (≤ 110 pg/mL) cerebrospinal fluid hypocretin-1 level.

RESULTS

Short REML (≤15 minutes) during NPSG was highly specific (99.2% [95% CI, 98.5%-100.0%] of 516 and 99.6% [95% CI, 99.1%-100.0%] of 735) but not sensitive (50.6% [95% CI, 46.3%-54.9%] of 516 and 35.7% [95% CI, 10.6%-60.8%] of 14) for patients with narcolepsy/hypocretin deficiency vs population-based controls or all patients with sleep disorders undergoing a nocturnal sleep study (area under the curve, 0.799 [95% CI, 0.771-0.826] and 0.704 [95% CI, 0.524-0.907], respectively). In patients with central hypersomnia and thus a high pretest probability for narcolepsy, short REML remained highly specific (95.4% [95% CI, 90.4%-98.3%] of 132) and similarly sensitive (57.4% [95% CI, 48.1%-66.3%] of 122) for narcolepsy/hypocretin deficiency (area under the curve, 0.765 [95% CI, 0.707-0.831]). Positive predictive value in this high pretest probability sample was 92.1% (95% CI, 83.6%-97.0%).

CONCLUSIONS AND RELEVANCE

Among patients being evaluated for possible narcolepsy, short REML (≤15 minutes) at NPSG had high specificity and positive predictive value and may be considered diagnostic without the use of an MSLT; absence of short REML, however, requires a subsequent MSLT.

Adolescents and young adults with Down syndrome presenting to a medical clinic with depression: co-morbid obstructive sleep apnea

Adolescents and young adults with Down syndrome (DS) sometimes experience new-onset mood disorder and decline in adaptive skills. The clinical phenomenon is poorly characterized and its pathogenesis is not understood. The possible contribution of obstructive sleep apnea syndrome (OSAS) to this phenomenon has not been studied. Subjects were ascertained as a convenience sample through our clinic for persons with DS and medical or mental health concerns between 2004 and 2009. When mood symptoms were present an axis I diagnosis was made using DSM-IV-R criteria. Subjects without an axis I diagnosis served as controls. The Reiss scales for children's dual diagnosis and the aberrant behavior checklist (ABC) were completed by caretakers. Twenty-eight cases meeting criteria for major depressive episode (MDE) and nine controls without psychopathology were referred for overnight polysomnography (PSG). Functional decline was reported in 19 (68%) of cases with MDE, but none of the controls. Twenty-four (86%) cases had OSAS compared with only 4 (44%) of controls. Moderate-severe OSAS was present in 15 (54%) of cases compared to only 1 (11%) of controls. Intermittent sleep-associated hypoxia and REM sleep deficits were also more frequent in cases. Across all subjects, prior tonsillectomy was not related to the presence or absence of OSAS. Our findings suggest that OSAS may be a common co-morbidity in adolescents and younger adults with DS and depression. Recognition of this association maybe critical to understanding the pathogenesis and management of mood-related disorders, and functional decline in affected individuals.

Declarative memory consolidation during the first night in a sleep lab: the role of REM sleep and cortisol

While the consolidation of declarative memory is supported by slow wave sleep (SWS) in healthy subjects, it has been shown to be associated with rapid eye movement (REM) sleep in patients with insomnia. Sleep during a subject's first night in an unfamiliar environment is often disturbed, and this so-called first-night effect (FNE) has often been used as a model of transient insomnia. Additionally, sleeping for the first time in an unfamiliar environment can lead to increased cortisol secretion, and declarative memory consolidation likely depends on low cortisol levels, especially during the early part of the night. Accounting for intersubject variability in the FNE, we examined the relationship between sleep stages, cortisol secretion and declarative memory performance in 27 healthy young men. Declarative memory performance improved significantly after sleep. Whereas memory performance during the learning session and retrieval testing was strongly associated with cortisol secretion, the overnight gain was not. Post hoc analyses indicated that the overnight gain appears to be modulated by the extent of the FNE: a significant overnight improvement in memory performance was found only in subjects with a weak FNE (n=12). In these subjects, no association was found between any sleep stage and the improvement observed in their memory performance. In subjects with a strong FNE (n=12), however, the overnight change in memory performance was associated with the proportion of REM sleep and the total number of REMs. Disturbed sleep in an unfamiliar environment therefore appears to affect the memory consolidation process.

Is a one-night stay in the lab really enough to conclude? First-night effect and night-to-night variability in polysomnographic recordings among different clinical population samples

While polysomnography remains the current gold standard in sleep investigation, guidelines for single night versus consecutive recordings in a sleep laboratory have been disputed mainly because of two phenomena: the first-night effect and night-to-night variability. One hundred and twenty nine subjects, that underwent two consecutive nights of polysomnographic recording in a general University Hospital's sleep lab, were divided into four groups: sleep-related breathing disorders (SRBD), insomnia, movement and behavioral disorders and a healthy control (HC) group based on their complaints at admission and sleep study results. Sleep parameters of both consecutive two nights were compared and analyzed. All groups showed a significant first-night effect. However the latter seemed more pronounced in the insomnia group. Furthermore, a clinically significant intra-patient night-to-night variability was found for the apnea-hypopnea index in the SRBD-group. Due to the observed first-night effect among any subject group and the potential impact of night-to-night variability of the apnea-hypopnea index, we conclude that the clinical assessment of sleep disorders should be similar in every patient. Hence, the present study underlines the importance of two consecutive nights of polysomnographic recording as a potential reference standard for the execution of sleep investigations.

The effects of moderate to vigorous aerobic exercise on the sleep need of sedentary young adults

Exercise has been recommended for enhancing sleep; a claim linked to the belief that sleep need - defined by sleep duration and depth - is increased post-exercise to allow tissue recovery. Objective studies investigating exercise-sleep responses have produced mixed outcomes, and the disparity in results between studies may be due to differences in individual characteristics and/or exercise protocol, emphasising the importance of carefully controlled trials. We investigated the role of exercise on the sleep need of sedentary adults, after controlling for exercise mode, timing and duration. Twelve healthy volunteers (25.2 ± 4.0 years, 9 females, [Vdot]O(2)max 35.4 ± 8.8 ml· kg(-1) · min(-1)) were randomised to no-exercise or to a bout of treadmill exercise at 45%, 55%, 65% or 75% [Vdot]O(2)max in a crossover design. Sleep on no-exercise and exercise nights were assessed by polysomnography. Participants spent a greater proportion of sleep in light sleep (stage 1 + stage 2) after exercise at both 65% and 75% [Vdot]O(2)max (P < 0.05) than the no-exercise condition. There was a trend of a reduced proportion of rapid eye movement sleep with increased exercise intensity (P = 0.067). No other changes were observed in any other sleep variables. Two findings emerged: vigorous exercise did not increase sleep need; however, this level of exercise increased light sleep.

Sleep-related arousal versus general cognitive arousal in primary insomnia

STUDY OBJECTIVES

The present study aimed at further investigating trait aspects of sleep-related cognitive arousal and general cognitive arousal and their association with both objective and subjective sleep parameters in primary insomnia patients.

METHODS

A clinical sample of 182 primary insomnia patients and 54 healthy controls was investigated using 2 nights of polysomnography, subjective sleep variables, and a questionnaire on sleep-related and general cognitive arousal.

RESULTS

Compared to healthy controls, primary insomnia patients showed both more sleep-related and general cognitive arousal. Furthermore, sleep-related cognitive arousal was closely associated with measures of sleep-onset and sleep-maintenance problems, while general cognitive arousal was not.

CONCLUSIONS

Cognitive-behavioral treatment for insomnia might benefit from dedicating more effort to psychological interventions that are able to reduce sleep-related cognitive arousal.

Travel-related change of residence leads to a transitory stress reaction in humans

OBJECTIVE

It is well known that animals show a stress response when confronted with a novel environment. The aim of the this study was to investigate whether humans show a similar response by studying the reaction to a travel-related transitory change of residence.

METHOD

Forty-eight individuals (32 women, 16 men, age 40-83 years) traveling to a health resort approximately 120 km from their home town participated in the study. Individuals monitored their blood pressure (BP) twice a day 3 weeks before (baseline) and during the stay and filled out a diary stating their mood and sleep. The change of the variables relative to baseline on the day before departure, the travel day, and the day after arrival as well as 5 days after arrival were determined.

RESULTS

Systolic and diastolic BPs were increased on the day before travel and diastolic BP remained increased on the travel day and the day after arrival. Sleep was poorer during the first night at the new residence. All three variables had returned to baseline level 5 days into the stay. Mood was not affected by the change of residence.

CONCLUSION

The results indicate that not only the change of residence but also its anticipation affects individuals in a transient way. The findings are relevant not only for the basic understanding of the reaction to novel environments but also to travel, tourism as well as rehabilitation, and spa-research.

Objective vs. subjective measurements of sleep in depressed insomniacs: first night effect or reverse first night effect?

STUDY OBJECTIVES

This study examined changes in sleep parameters between the laboratory and the home setting before and after laboratory monitoring in depressed insomniacs undergoing treatment.

METHODS

This study was a post hoc analysis of a double-blind, randomized, placebo-controlled clinical trial performed with 60 depressed, insomniac outpatients. Patients underwent actigraphic monitoring along with sleep diaries over a continuous 2-week period. After one week of baseline monitoring, subjects spent one night in the laboratory with concurrent actigraphic and PSG monitoring with sleep diaries. Actigraphic monitoring and sleep diaries were continued for another week at home, along with initiation of open-label fluoxetine (FLX).

RESULTS

Actigraphically recorded laboratory sleep during the night in the laboratory was found to be improved relative to actigraphically recorded sleep at home, with less wake time and greater sleep time and sleep efficiency occurring in the laboratory. In contrast, sleep diaries indicated a slight worsening of sleep in the laboratory compared to home, with significantly more awakenings in the laboratory compared to the week at home before and after the laboratory night.

CONCLUSIONS

The differences between objective and subjective sleep measurements seen in depressed insomniacs may be influenced by the monitoring setting and measurement modality.

CLINICAL TRIAL INFORMATION

ClinicalTrials.gov Identifier: NCT00247624.

Time will tell: a retrospective study investigating the relationship between insomnia and objectively defined punctuality

Primary insomnia is a prevalent sleep disorder affecting approximately 3% of the general population. Studies suggest that personality traits such as perfectionism and neuroticism might be implicated in the aetiology of the disorder. However, to date, no study has investigated behavioural indicators of these factors in a hypothesis-driven manner. In the present study, we assessed punctuality as a behavioural indicator of perfectionism and neuroticism in 635 consecutive clinical patients of the sleep laboratory of the Department of Psychiatry and Psychotherapy, University of Freiburg Medical Center. The primary aim was to compare primary insomnia patients (n = 148) with another group of patients with other sleep-related diagnoses (n = 487). Primary insomnia patients arrived on average 4 min earlier when compared to other patients (P = 0.041). However, this effect failed to reach statistical significance when correcting for the influence of potential confounding variables. Of note, we found a strong relationship between polysomnographic sleep parameters and punctuality. That is, short sleep duration was associated significantly with early arrival times at the sleep laboratory (P = 0.023). These findings support the proposal that personality traits, which we predict underlie obsessive punctuality, may be involved in the aetiology of objectively defined sleep disturbances. Clinical implications of the current results for cognitive behavioural treatments of insomnia are discussed.

Wrist actigraphy

To record sleep, actigraph devices are worn on the wrist and record movements that can be used to estimate sleep parameters with specialized algorithms in computer software programs. With the recent establishment of a Current Procedural Terminology code for wrist actigraphy, this technology is being used increasingly in clinical settings as actigraphy has the advantage of providing objective information on sleep habits in the patient's natural sleep environment. Actigraphy has been well validated for the estimation of nighttime sleep parameters across age groups, but the validity of the estimation of sleep-onset latency and daytime sleeping is limited. Clinical guidelines and research suggest that wrist actigraphy is particularly useful in the documentation of sleep patterns prior to a multiple sleep latency test, in the evaluation of circadian rhythm sleep disorders, to evaluate treatment outcomes, and as an adjunct to home monitoring of sleep-disordered breathing. Actigraphy has also been well studied in the evaluation of sleep in the context of depression and dementia. Although actigraphy should not be viewed as a substitute for clinical interviews, sleep diaries, or overnight polysomnography when indicated, it can provide useful information about sleep in the natural sleep environment and/or when extended monitoring is clinically indicated.

Anxiety and heart rate variability before sleep indicate chronic stress in students

The purpose of the present study was to investigate the effect of chronic stress on the first-night effect in terms of autonomic nervous system activity and anxiety. Participants (N = 11; M age = 20.3 yr., SD = 0.47) included six with high stress (High stress group) and five with low stress (Low stress group), for whom all EEG data were available from three consecutive nights. Heart rate variability was calculated using the MemCalc method. The ratio of low to high frequency of heart rate variability before sleep onset in the High stress group on the first night indicated significantly higher activities than the ratio before sleep onset in the Low stress group. No significant difference in sleep latency was found between the two groups. However, the High stress group was more aware of anxiety than was the Low stress group, and the former estimated more subjective difficulty in falling asleep. These results suggest that measuring LF/HF before sleep may constitute a new way to assess chronic stress.

Slow wave sleep deficits as a trait marker in patients with schizophrenia

BACKGROUND

Among the sleep abnormalities found in schizophrenia, slow wave sleep deficits have been found to persist even after the resolution of active psychotic symptoms. Further, such abnormalities are observed in young healthy individuals at high risk of schizophrenia, which suggest that slow wave sleep deficits might be trait marker in schizophrenia.

METHODS

Sleep EEG was recorded in 20 right handed patients aged 18-45 years with ICD-10 DCR diagnosis of schizophrenia, 14 first degree relatives and 20 age and sex matched controls. Patients were rated on Positive and Negative Syndrome Scale (PANSS) and Brief Psychiatric Rating Scale (BPRS) for assessment of psychopathology.

RESULTS

There was significant difference between the three groups in total sleep period (p<.01), total sleep time (p<.01), stage shifts (p<.05), stage 1 percentage of total sleep time (p<.05), stage 2 duration (p<.05), stage 3 latency (p<.05), stage 4 duration (p<.01) and stage 4 percentage of total sleep time (p<.01). There was significant positive correlation of REM percentage of total sleep time with BPRS total score (r(s) = .488, p = .029) and PANSS positive score (r(s) = .583, p = .007), whereas significant negative correlation of REM latency was found with BPRS total score (r(s) = -.640, p = .002) and PANSS positive score (r(s) = -.657, p = .002) in the patients.

CONCLUSIONS

Slow wave sleep deficits are a possible trait marker in patients with schizophrenia, which needs replication in further studies.

Adaptation effects to sleep studies in participants with and without chronic posttraumatic stress disorder

The "first night effect" (FNE) is the alteration of sleep architecture observed on the first night of polysomnographic (PSG) studies. It is unclear whether the FNE reflects adaptation to the equipment, sleeping environment, or both. Moreover, it is possible that certain patient populations, such as those with posttraumatic stress disorder (PTSD), demonstrate greater adaptation effects that are highly context dependent. We assessed FNE in participants with PTSD and healthy controls in a cross-sectional study consisting of PSG testing at home and in the hospital. Contrary to our expectations, the PTSD group showed no adaptation effects in either setting. Only the control group assigned to the "hospital first" condition showed significant decreases in total sleep time on night 1 versus night 2 of the study. The results suggest that the FNE is related to adaptation to the combination of the hospital environment and the recording equipment.

Prospective associations of insomnia markers and symptoms with depression

Whether insomnia, a known correlate of depression, predicts depression longitudinally warrants elucidation. The authors examined 555 Wisconsin Sleep Cohort Study participants aged 33-71 years without baseline depression or antidepressant use who completed baseline and follow-up overnight polysomnography and had complete questionnaire-based data on insomnia and depression for 1998-2006. Using Poisson regression, they estimated relative risks for depression (Zung scale score > or =50) at 4-year (average) follow-up according to baseline insomnia symptoms and polysomnographic markers. Twenty-six participants (4.7%) developed depression by follow-up. Having 3-4 insomnia symptoms versus none predicted depression risk (age-, sex-, and comorbidity-adjusted relative risk (RR) = 3.2, 95% confidence interval: 1.1, 9.6). After multiple adjustments, frequent difficulty falling asleep (RR = 5.3, 95% confidence interval: 1.1, 27.9) and polysomnographically assessed (upper or lower quartiles) sleep latency, continuity, and duration (RRs = 2.2-4.7; P's < or = 0.05) predicted depression. Graded trends (P-trend < or = 0.05) were observed with increasing number of symptoms, difficulty falling asleep, and difficulty returning to sleep. Given the small number of events using Zung > or =50 (depression cutpoint), a limitation that may bias multivariable estimates, continuous depression scores were analyzed; mean values were largely consistent with dichotomous findings. Insomnia symptoms or markers increased depression risk 2.2- to 5.3-fold. These results support prior findings based on self-reported insomnia and may extend similar conclusions to objective markers. Heightened recognition and treatment of insomnia may prevent subsequent depression.