Daytime alertness in relation to mood, performance, and nocturnal sleep in chronic insomniacs and noncomplaining sleepers

Insomnia nosology: a systematic review and critical appraisal of historical diagnostic categories and current phenotypes

Insomnia nosology has significantly evolved since the Diagnostic and Statistical Manual (DSM)-III-R first distinguished between 'primary' and 'secondary' insomnia. Prior International Classification of Sleep Disorders (ICSD) nosology 'split' diagnostic phenotypes to address insomnia's heterogeneity and the DSM nosology 'lumped' them into primary insomnia, while both systems assumed causality for insomnia secondary to health conditions. In this systematic review, we discuss the historical phenotypes in prior insomnia nosology, present findings for currently proposed insomnia phenotypes based on more robust approaches, and critically appraise the most relevant ones. Electronic databases PsychINFO, PubMED, Web of Science, and references of eligible articles, were accessed to find diagnostic manuals, literature on insomnia phenotypes, including systematic reviews or meta-analysis, and assessments of the reliability or validity of insomnia diagnoses, identifying 184 articles. The data show that previous insomnia diagnoses lacked reliability and validity, leading current DSM-5-TR and ICSD-3 nosology to 'lump' phenotypes into a single diagnosis comorbid with health conditions. However, at least two new, robust insomnia phenotyping approaches were identified. One approach is multidimensional-multimethod and provides evidence for self-reported insomnia with objective short versus normal sleep duration linked to clinically relevant outcomes, while the other is multidimensional and provides evidence for two to five clusters (phenotypes) based on self-reported trait, state, and/or life-history data. Some approaches still need replication to better support whether their findings identify true phenotypes or simply different patterns of symptomatology. Regardless, these phenotyping efforts aim at improving insomnia nosology both as a classification system and as a mechanism to guide treatment.

Personality and insomnia: A systematic review and narrative synthesis

The inherent nature of personality serves as a predisposing, and possible maintaining, factor of insomnia. However, methodological differences limit the ability to draw causal conclusions regarding the specific traits involved in the aetiology of the disorder. This systematic review of the relationship between insomnia and personality provides a narrative synthesis of the literature to date. Here, we identified N = 76 studies meeting the inclusion/exclusion criteria. The outcomes reliably evidenced the experience of insomnia to be associated with personality traits that are typically considered to be negative or maladaptive in nature. More specifically, insomnia was related to neuroticism, introversion, perfectionistic doubts and concerns, elevated personal standards, negative affect, social inhibition and avoidance, hysteria, hypochondriasis, psychasthenia, impulsive behaviour, anger, hostility, and psychopathic tendencies, schizotypal and borderline traits, reduced conscientiousness and self-directedness, and negatively perceived perception of the self. Several studies examined the role that personality plays in predicting the treatment efficacy and adherence of CBTi. Moving forward, longitudinal research, methodological consistency, the mediating role of treatment outcomes and adherence, and clinical and population representative samples should be prioritised. Methodological strengths and limitations of the literature are discussed alongside the next steps that should be taken to advance our understanding of the literature.

Elevated beta activity in the nighttime sleep and multiple sleep latency electroencephalograms of chronic insomnia patients

Aim

To examine the 24-h hyperarousal hypothesis of insomnia using electroencephalographic (EEG) spectral analysis of overnight polysomnography (PSG) and daytime multiple sleep latency tests (MSLTs).

Methods

Standard PSG and MSLT were recorded in 31 chronic insomniacs (CIs) (21 females, mean age 36.19) and in 21 normal controls (NCs) (18 females, mean age 34.76). EEG spectral analyses were conducted and relative power was obtained for each sleep stage during PSG and each session during MSLTs. Subsequently, CIs were subdivided based on sleep efficiency (SE < or ≥ 85%) or mean sleep latency (MSL) of MSLT (< or ≥ 15 min), and beta power was compared among NCs and CIs subgroups. General liner regression analyses of beta power and PSG parameters were conducted.

Results

CIs had significantly greater beta power in nighttime W, N1, N2, NREM, and in total overnight and in MSLT sessions compared with NCs. CIs with lower PSG-SE or longer MSLT-MSL showed higher beta power at nighttime. Compared with NCs, increased beta power was limited to CIs with lower PSG-SE or longer MSLT-MSL during MSLT sessions. In all subjects, total daytime beta was positively correlated to total overnight beta and MSL, total overnight beta was negatively related to SE. In CIs, total daytime beta and total overnight beta were positively correlated.

Conclusion

Our results support the hypothesis of 24-h cortical hyperarousal in insomnia. We conclude that 24-h cortical hyperarousal is clearly present in insomnia and is greater in insomnia with objective findings.

Electrodermal Activity Is Sensitive to Sleep Deprivation but Does Not Moderate the Effect of Total Sleep Deprivation on Affect

Emotion is characterized by dimensions of affective valence and arousal, either or both of which may be altered by sleep loss, thereby contributing to impaired regulatory functioning. Controlled laboratory studies of total sleep deprivation (TSD) generally show alterations in physiological arousal and affective state, but the relationship of affect and emotion with physiological arousal during TSD has not been well characterized. Established methods for examining physiological arousal include electrodermal activity (EDA) measures such as non-specific skin conductance responses (NSSCR) and skin conductance level (SCL). These measures are robust physiological markers of sympathetic arousal and have been linked to changes in experienced emotion. To explore the link between physiological arousal and affect during sleep deprivation, we investigated individuals’ EDA under TSD and its relationship to self-reported affect. We also investigated the relationship of EDA to two other measures known to be particularly sensitive to the arousal-decreasing effects of TSD, i.e., self-reported sleepiness and performance on a vigilant attention task. Data were drawn from three previously published laboratory experiments where participants were randomly assigned to either well-rested control (WRC) or 38 h of TSD. In this data set, comprising one of the largest samples ever used in an investigation of TSD and EDA (N = 193 with 74 WRC and 119 TSD), we found the expected impairing effects of TSD on self-reported affect and sleepiness and on vigilant attention. Furthermore, we found that NSSCR, but not SCL, were sensitive to TSD, with significant systematic inter-individual differences. Across individuals, the change in frequency of NSSCR during TSD was not predictive of the effect of TSD on affect, sleepiness, or vigilant attention, nor was it related to these outcomes during the rested baseline. Our findings indicate that while physiological arousal, as measured by EDA, may be useful for assessing TSD-related changes in non-specific arousal at the group level, it is not associated with individuals’ self-reported affect at rest nor their change in affect during TSD. This suggests that an essential aspect of the relationship between physiological arousal and self-reported affect is not well captured by EDA as measured by NSSCR.

Optimizing computation of overnight decline in delta power: Evidence for slower rate of decline in delta power in insomnia patients

OBJECTIVE

To determine the best of commonly used methods for computing the rate of decline in non-rapid eye movement (NREM) sleep EEG delta power overnight (Delta Decline) in terms of vulnerability to missing data and to evaluate whether this rate is slower in insomnia patients than healthy controls (HC).

METHODS

Fifty-one insomnia patients and 53 HC underwent 6 nights of polysomnography. Four methods for estimating Delta Decline were compared (exponential and linear best-fit functions using NREM (1) episode mean, (2) peak, and (3) total delta power and (4) delta power for all available NREM epochs). The best method was applied to compare groups on linear and exponential rates of Delta Decline.

RESULTS

Best-fit models using all available NREM epochs were significantly less vulnerable to deviation due to missing data than other methods. Insomnia patients displayed significantly slower linear and exponential Delta Decline than HC.

CONCLUSIONS

Computing Delta Decline using all available NREM epochs was the best of the methods studied for minimizing the effects of missing data. Insomnia patients display slower Delta Decline, which is not explained by differences in total sleep time or wake after sleep onset.

SIGNIFICANCE

This study supports using all available NREM epochs in Delta Decline computation and suggests a slower rate in insomnia.

Insomnia and cognitive performance: A systematic review and meta-analysis

Cognitive performance has been extensively investigated in relation to insomnia, yet review of the literature reveals discrepant findings. The current study aimed to synthesize this literature with a systematic review and meta-analysis. 48 studies (k = 50 independent samples, n = 4539 total participants) met inclusion criteria. Omnibus meta-analysis revealed insomnia was associated with poorer overall cognitive performance (Hedge's g = -0.24, p < 0.001). Analyses by cognitive domain revealed insomnia was specifically associated with impairments in subjective cognitive performance (g = -0.35), and objective measures of perceptual function (g = -0.24), manipulation (g = -0.52) and retention/capacity in working memory (g = -0.30), complex attention (g = -0.36), alertness (g = -0.14), episodic memory (g = -0.29), and problem solving in executive functions (g = -0.39). Age, percent female, publication year, and insomnia measure did not consistently moderate findings. Approximately 44% of studies failed to use diagnostic criteria when categorizing insomnia and cognitive measures varied widely. This indicates a need for standardization of methods assessing insomnia and cognitive performance in research. Overall, findings from this meta-analysis indicate insomnia is associated with impairment in objective and subjective cognitive performance, highlighting the utility of treating insomnia to potentially improve cognitive outcomes.

Short- and Long-Term Effects of CBT-I in Groups for School-Age Children Suffering From Chronic Insomnia: The KiSS-Program

OBJECTIVE/BACKGROUND

This intervention study evaluates the short- and long-term effects of cognitive behavior therapy for insomnia (CBT-I) in groups for school-age children and their parents, named the KiSS-program. CBT-I was implemented in three sessions for children and three sessions for parents.

PARTICIPANTS AND METHODS

All in all, 112 children with chronic childhood insomnia were randomly assigned to a wait-list (WL) control or treatment condition.

RESULTS

According to subjective measures as well as objective wrist actigraphy, children in the CBT-I condition reported greater improvements in sleep behavior immediately after the treatment compared to the WL group. Improvements in sleep behavior after CBT-I persisted over the 3-, 6-, and 12-month follow-up assessments.

CONCLUSIONS

The present study is the first randomized controlled trial that provides evidence for the long-term effectiveness of CBT-I in treating school-age children with chronic insomnia.

Sleep: important considerations for the prevention of cardiovascular disease

PURPOSE OF REVIEW

Sleep plays many roles in maintenance of cardiovascular health. This review summarizes the literature across several areas of sleep and sleep disorders in relation to cardiometabolic disease risk factors.

RECENT FINDINGS

Insufficient sleep duration is prevalent in the population and is associated with weight gain and obesity, inflammation, cardiovascular disease, diabetes, and mortality. Insomnia is also highly present and represents an important risk factor for cardiovascular disease, especially when accompanied by short sleep duration. Sleep apnea is a well-characterized risk factor for cardiometabolic disease and cardiovascular mortality. Other issues are relevant as well. For example, sleep disorders in pediatric populations may convey cardiovascular risks. Also, sleep may play an important role in cardiovascular health disparities.

SUMMARY

Sleep and sleep disorders are implicated in cardiometabolic disease risk. This review addresses these and other issues, concluding with recommendations for research and clinical practice.

Increased Mortality in Relation to Insomnia and Obstructive Sleep Apnea in Korean Patients Studied with Nocturnal Polysomnography

STUDY OBJECTIVES

To elucidate the links between the two most prevalent sleep disorders, insomnia and obstructive sleep apnea (OSA), and mortality.

METHODS

We studied 4,225 subjects who were referred to the Center for Sleep and Chronobiology, Seoul National University Hospital, from January 1994 to December 2008. We divided the subjects into five groups: mild OSA (5 ≤ AHI < 15), moderate OSA (15 ≤ AHI < 30), severe OSA (AHI ≥ 30), insomnia, and a no-sleep-disorder group consisting of subjects without sleep disorders. Standardized mortality ratio (SMR), hazard ratio, and the survival rates of the five groups were calculated and evaluated.

RESULTS

The SMR of all-cause mortality was significantly higher in the severe OSA group than in the general population (1.52, 95% CI 1.23-1.85, p < 0.05). The SMR of cardiovascular mortality increased progressively with the severity of OSA (no-sleep-disorder: 0.09, mild: 0.40, moderate: 0.52, severe: 1.79, p < 0.05). Statistical analyses of the hazard ratios indicated that severe OSA is a risk factor for all-cause mortality (HR 3.50, 95% CI 1.03-11.91, p = 0.045) and cardiovascular mortality (HR 17.16, 95% CI 2.29-128.83, p = 0.006). Cardiovascular mortality was also significantly elevated in the insomnia group (HR 8.11, 95% CI 1.03-63.58, p = 0.046).

CONCLUSIONS

Severe OSA was associated with increased all-cause mortality and cardiovascular mortality compared to the no-sleep-disorder group. Insomnia was associated with increased cardiovascular mortality compared to the no-sleep-disorder group.

Hyperarousal in insomnia and hypnotic dose escalation

BACKGROUND

Given concerns about the abuse liability of hypnotics, this study assessed hyperarousal in people with insomnia and its relation to hypnotic self-administration over 12 months of nightly hypnotic use.

METHODS

Ninety-five subjects with insomnia (age 32-64 years) underwent screening nocturnal polysomnogram (NPSG) and Multiple Sleep Latency Test (MSLT) the following day and, then, were randomized to receive zolpidem 10 mg or placebo nightly for 12 months. NPSGs and MSLTs were conducted and urine was collected (0700-1500 h) and analyzed for norepinephrine (NE) levels during months one and eight on study medication. A subset (n = 54) underwent hypnotic self-administration assessments in months one, four, and 12.

RESULTS

Mean daily sleep latency on screening MSLT was distributed across the full range of MSLT latencies (2-20 min). The highest screening MSLT latencies were detected in subjects with higher NE levels, compared to those with the lowest MSLT latencies. In the subset undergoing self-administration assessment, those with the highest MSLT latencies chose more capsules (placebo and zolpidem) and increased the number of capsules chosen in months four relative to month one, compared to those with the lowest MSLT latencies.

CONCLUSIONS

These data show that some insomniacs are hyperaroused with high MSLT/NE levels and, compared to low MSLT/NE insomniacs, they increase the number of capsules (zolpidem and placebo) self-administered on months four and 12 relative to Month one.

Efficacy of paced breathing for insomnia: enhances vagal activity and improves sleep quality

Fourteen self-reported insomniacs (SRI) and 14 good sleepers (GS) had their cardiac neuronal activity assessed by heart rate variability (HRV) under controlled respiration at a slow frequency rate of 0.1 Hz, and a forced rate of 0.2 Hz during daytime rest. Nighttime sleep was measured by polysomnography. The SRI showed depressed high frequency power of HRV compared to the GS. An increased total power of HRV was observed among the SRI during slow, paced breathing compared with spontaneous breathing and 0.2 Hz. Sleep onset latency, number of awakenings, and awakening time during sleep were decreased and sleep efficiency was increased if SRI practiced slow, paced breathing exercises for 20 min before going to sleep. Our results indicate that there is autonomic dysfunction among insomniacs, especially in relation to vagal activity; however, this decreased vagal activity can be facilitated by practicing slow, paced breathing, thereby improving sleep quality.

Increased use-dependent plasticity in chronic insomnia

STUDY OBJECTIVES

During normal sleep several neuroplasticity changes occur, some of which are considered to be fundamental to strengthen memories. Given the evidence linking sleep to neuroplasticity, it is conceivable that individuals with chronic sleep disruption, such as patients with chronic insomnia (CI), would experience abnormalities in neuroplastic processes during daytime. Protocols testing use-dependent plasticity (UDP), one of the mechanisms underlying formation of motor memories traces, provide a sensitive measure to assess neuroplasticity in the context of motor training.

DESIGN AND PARTICIPANTS

A well-established transcranial magnetic stimulation (TMS) paradigm was used to evaluate the ability of patients with CI and age-matched good sleeper controls to undergo UDP. We also investigated the effect of insomnia on intracortical motor excitability measures reflecting GABAergic and glutamatergic mechanisms.

SETTING

Human Brain Physiology Laboratory, Johns Hopkins Medical Institutions.

MEASUREMENTS AND RESULTS

We found that patients with CI experienced increased UDP changes relative to controls. This effect was not due to differences in motor training. In addition, patients with CI showed enhanced intracortical facilitation relative to controls, in the absence of changes in intracortical inhibitory measures.

CONCLUSION

This study provides the first evidence that patients with chronic insomnia have an increased plasticity response to physical exercise, possibly due to larger activation of glutamatergic mechanisms. This suggests a heightened state of neuroplasticity, which may reflect a form of maladaptive plasticity, similar to what has been described in dystonia patients and chronic phantom pain after amputation. These results could lead to development of novel treatments for chronic insomnia.

Types of primary insomnia: is hyperarousal also present during napping?

STUDY OBJECTIVES

The objective of this study was to identify if hyperarousal is a 24-hour phenomenon in insomnia by comparing sleep during napping between good sleepers (GS) and Insomnia sufferers (INS) (subdivided into paradoxical "PARA-I" and psychophysiological "PSY-I") following a mentally challenging battery of cognitive tests.

DESIGN

Cross-sectional comparisons of GS, PSY-I, and PARA-I.

SETTING

Participants slept for 4 consecutive nights in the laboratory where PSG was recorded. Upon awakening on mornings 2 and 3, cognitive testing (lasting 90-120 min) was administered, followed by a 20-minute nap.

PARTICIPANTS

Fourteen PSY-I, 12 PARA-I, and 23 GS completed the study, comprising home questionnaires, clinical interviews, night PSG recordings, cognitive testing, and nap PSG recordings. All participants were between 25 and 50 years of age and met inclusion criteria for PSY-I, PARA-I, or GS.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

On objective nap parameters, GS had a longer total sleep time (TST; p = 0.008) and better sleep efficiency (SE; p = 0.009), than PSY-I and PARA-I, and both groups of INS were awake significantly longer than GS (p = 0.003). Also, PARA-I took significantly more time than GS to fall asleep (p = 0.014). Subjectively reported sleepiness was comparable across the three groups. Positive relationships were observed between SE over the night and SE over the nap the following day.

CONCLUSIONS

Results show that GS sleep better than INS during naps following prolonged cognitive testing, suggesting that, in INS, hyperarousal predominates over mental fatigue resulting from these tests. These results may parallel what is observed at night when INS experience increased cognitive load but are unable to fall asleep.

Insomnia and its impact on physical and mental health

In contrast to the association of insomnia with mental health, its association with physical health has remained largely unexplored until recently. Based on findings that insomnia with objective short sleep duration is associated with activation of both limbs of the stress system and other indices of physiological hyperarousal, which should adversely affect physical and mental health, we have recently demonstrated that this insomnia phenotype is associated with a significant risk of cardiometabolic and neurocognitive morbidity and mortality. In contrast, insomnia with normal sleep duration is associated with sleep misperception and cognitive-emotional arousal, but not with signs of physiological hyperarousal or cardiometabolic or neurocognitive morbidity. Interestingly, both insomnia phenotypes are associated with mental health, although most likely through different pathophysiological mechanisms. We propose that objective measures of sleep duration may become part of the routine evaluation and diagnosis of insomnia, and that these two insomnia phenotypes may respond differentially to biological versus psychological treatments.

Insomnia with Short Sleep Duration: Nosological, Diagnostic, and Treatment Implications

The diagnosis of insomnia is based solely on subjective complaints. This has contributed to the low reliability and validity of the current nosology of insomnia as well as to its lack of firm association with clinically relevant outcomes such as cardiometabolic and neurocognitive morbidity. We review evidence that insomnia with objective short sleep duration is associated with physiological hyperarousal, higher risk for hypertension, diabetes, neurocognitive impairment, and mortality as well as with a persistent course. It also appears that objective short sleep duration in poor sleepers is a biological marker of genetic predisposition to chronic insomnia. In contrast, insomnia with objective normal sleep duration is associated with cognitive-emotional and cortical arousal and sleep misperception but not with signs of physiological hyperarousal or medical complications. Thus, short sleep duration in insomnia may be a reliable marker of the biological severity and medical impact of the disorder. We propose that (a) objective measures of sleep be included in the diagnosis of insomnia and its subtypes, (b) objective measures of sleep obtained in the home environment of the patient would become part of the routine assessment and diagnosis of insomnia in a clinician's office setting, and (c) insomnia with short sleep duration may respond better to biological treatments, whereas insomnia with normal sleep duration may respond primarily to psychological therapies.

Insomnia with objective short sleep duration: the most biologically severe phenotype of the disorder

Until recently, the association of chronic insomnia with significant medical morbidity was not established and its diagnosis was based solely on subjective complaints. We present evidence that insomnia with objective short sleep duration is the most biologically severe phenotype of the disorder, as it is associated with cognitive-emotional and cortical arousal, activation of both limbs of the stress system, and a higher risk for hypertension, impaired heart rate variability, diabetes, neurocognitive impairment, and mortality. Also, it appears that objective short sleep duration is a biological marker of genetic predisposition to chronic insomnia. In contrast, insomnia with objective normal sleep duration is associated with cognitive-emotional and cortical arousal and sleep misperception but not with signs of activation of both limbs of the stress system or medical complications. Furthermore, the first phenotype is associated with unremitting course, whereas the latter is more likely to remit. We propose that short sleep duration in insomnia is a reliable marker of the biological severity and medical impact of the disorder. Objective measures of sleep obtained in the home environment of the patient would become part of the routine assessment of insomnia patients in a clinician's office setting. We speculate that insomnia with objective short sleep duration has primarily biological roots and may respond better to biological treatments, whereas insomnia with objective normal sleep duration has primarily psychological roots and may respond better to psychological interventions alone.

Regulation of sleepiness: the role of the arousal system

Sleepiness is a widespread phenomenon in the busy industrial countries, and many studies have identified its significant negative impacts on individuals and society. Particularly important are the data that associate sleepiness with the risk of accidents at workplace and in transport, pointing to shift workers as the most vulnerable population. It is generally accepted that two basic physiological processes regulate sleepiness: homeostatic and circadian rhythmic processes. Recent research has proposed the third component regulating sleepiness, that is, the wake drive or the arousal system. The role of the arousal system in regulating sleepiness has partly been addressed by the studies of the pathophysiology of insomnia, which is often described as a disorder of hyperarousal. Experimental and correlational studies on the relation between sleepiness and arousal in good sleepers have generally indicated that both physiological and cognitive arousal are related to the standard measures of sleepiness. Taking into account the role of the arousal system in regulating sleepiness widens the possibilities for the management of sleep disorders and could also help in solving the problem of excessive sleepiness at work and the wheel.

Sleep perception and the multiple sleep latency test in patients with primary insomnia

The purpose of this study was to examine the relationship between overnight sleep perception and the daytime multiple sleep latency test (MSLT) among individuals who were primary insomnia patients (PIPs) or good sleeper controls (GSCs). We collected overnight sleep data via polysomnography (PSG), subjective sleep data via a morning questionnaire (self-evaluated) and MSLT data via four 20-min naps over 8 h. Subjects included 122 PIPs and 48 GSCs. Sleep perception was calculated as subjective sleep time/objective sleep time × 100%. PIPs showed a significant difference (P < 0.001) between sleep time, as determined by PSG (387.8 ± 100 min) and self-report (226.3 ± 160 min), but no difference was obtained for GSCs (440.6 ± 53 versus 435.4 ± 65 min). The means for sleep perception were 56.4 ± 38.8% for the PIPs and 99.3 ± 13.6% for the GSCs (P < 0.001). In the PIPs group, weak but statistically significant negative correlations (r: -0.20 to -0.25) were found for MSLT versus sleep perception and versus self- and PSG-evaluated sleep time. Compared to PIPs with low scores on the MSLT, those with high scores had less sleep perception (%), less self- and PSG-evaluated sleep time and greater sleep misperception time. GSCs did not show significant correlations between MSLT and sleep measures or differences in comparisons between individuals with high and low scores on the MSLT. These results add novel data to the literature by suggesting that 24-h hyperarousal potentially plays a key role in the pathophysiological issues of insomnia.

(Mis)perception of sleep in insomnia: a puzzle and a resolution

Insomnia is prevalent, causing severe distress and impairment. This review focuses on illuminating the puzzling finding that many insomnia patients misperceive their sleep. They overestimate their sleep onset latency (SOL) and underestimate their total sleep time (TST), relative to objective measures. This tendency is ubiquitous (although not universal). Resolving this puzzle has clinical, theoretical, and public health importance. There are implications for assessment, definition, and treatment. Moreover, solving the puzzle creates an opportunity for real-world applications of theories from clinical, perceptual, and social psychology as well as neuroscience. Herein we evaluate 13 possible resolutions to the puzzle. Specifically, we consider the possible contribution, to misperception, of (1) features inherent to the context of sleep (e.g., darkness); (2) the definition of sleep onset, which may lack sensitivity for insomnia patients; (3) insomnia being an exaggerated sleep complaint; (4) psychological distress causing magnification; (5) a deficit in time estimation ability; (6) sleep being misperceived as wake; (7) worry and selective attention toward sleep-related threats; (8) a memory bias influenced by current symptoms and emotions, a confirmation bias/belief bias, or a recall bias linked to the intensity/recency of symptoms; (9) heightened physiological arousal; (10) elevated cortical arousal; (11) the presence of brief awakenings; (12) a fault in neuronal circuitry; and (13) there being 2 insomnia subtypes (one with and one without misperception). The best supported resolutions were misperception of sleep as wake, worry, and brief awakenings. A deficit in time estimation ability was not supported. We conclude by proposing several integrative solutions.

MSLT in primary insomnia: stability and relation to nocturnal sleep

STUDY OBJECTIVES

To assess the stability of the multiple sleep latency test (MSLT) in primary insomnia and its relation to total sleep time.

DESIGN

Randomized, double-blind, placebo controlled, clinical trial.

SETTING

Outpatient with sleep laboratory assessments in months 1 and 8 of treatment.

PARTICIPANTS

Ninety-five primary insomniacs, 32-64 years old and 55 age- and sex-matched general population-based, representative controls.

INTERVENTIONS

After a screening nocturnal polysomnograms (NPSG) and MSLT the following day, participants with primary insomnia were randomized to take zolpidem 10 mg (n = 50) or placebo (n = 45) nightly for 12 months. During months 1 and 8, while taking their prescribed treatments, NPSGs and MSLTs the following day were conducted. A population-based sample served as controls and received a single NPSG followed by MSLT.

RESULTS

Mean daily sleep latency on the screening MSLT of insomniacs was normally distributed across the full range of MSLT scores and significantly higher than those of a population-based representative control sample (P < 0.006). The insomniacs with the highest screening MSLTs had the shortest screening total sleep times (P < 0.05). The MSLTs of insomniacs during treatment in study month 1 were correlated (r = 0.44, P < 0.001) with their month 8 MSLT. The mean MSLT score of the zolpidem group did not differ from that of the placebo group, and the stability within treatment groups also did not differ.

CONCLUSIONS

These data support the hypothesis that some insomniacs show a reliable disorder of hyperarousal with increased wake drive both at night and during the day.

The options available in cognitive behavioral therapy to prevent chronification of insomnia

Insomnia is a very frequent problem among the general population, and it has a high socio-economic impact on health care management. It produces high costs because of absenteeism and accidents, and it is considered to be a risk factor for the development of psychiatric diseases and other medical disorders. However, only a low proportion of insomniacs ever seek professional help. The reasons are still unknown, but most insomniacs probably consider their problem untreatable unless they undergo a therapy with hypnotics. Knowledge about alternative therapy methods beyond sleep medication is scarce, and specialized psychotherapy is not always available. Since dysfunctional behavior and beliefs are considered to be the central perpetuating factors for primary insomnia, the role of educational programs in terms of prevention and treating mild forms of insomnia is discussed. These workshops could be a part of a step-by-step treatment of insomnia as has been proposed recently by Espie.

Night-to-night sleep variability in older adults with and without chronic insomnia

OBJECTIVES

(1) To quantify night-to-night variability in sleep behaviors and sleep measures among older chronic insomnia (CI) subjects and non-insomnia (NI) controls; (2) to investigate systematic temporal patterns of sleep behaviors and sleep measures across nights; and (3) to examine clinical correlates of sleep variability.

METHODS

Sixty-one older adults with CI (71.4years old, 67% F) and 31 older adults with NI (70.7years old, 65% F) completed questionnaires, kept sleep diaries and wore wrist actigraphs for 2 weeks. Mixed models were used to estimate within-subject mean and standard deviation values; these were then compared across groups. Mixed models were also used to determine associations across nights of sleep measures.

RESULTS

CI and NI differed on mean values for clinical ratings and sleep diary measures, but not for actigraphy measures. CI also showed significantly greater variability than NI on most sleep diary measures and on actigraphically measured wakefulness after sleep onset (WASO) and sleep efficiency. Among CI, neither diary nor actigraphy measures from one night correlated with values from the previous night. Diary WASO, sleep time, actigraphy sleep latency and sleep time, however, positively correlated with values from the previous two nights. Variability measures were not correlated with other global clinical measures among CI.

CONCLUSIONS

Compared to NI, older adults with CI report worse sleep and greater night-to-night variability, which was confirmed with actigraphy. There was little evidence for positive or negative correlation of sleep measures across nights. Variability of sleep may be an important target for insomnia treatments.

The role of personality traits in insomnia

Insomnia is a highly prevalent sleep disorder, known to affect psychological well-being and quality of life. While perpetuating factors have received much attention, the role of predisposing factors has not been studied in much detail. The susceptibility to develop insomnia may be linked to the presence of certain personality features. Here, we review studies that assessed this particular aspect of insomnia. Due to various methodological issues, definitive conclusions cannot be drawn as of yet, and several conflicting findings remain. However, there is a common trend indicating that insomniacs display more signs of 'neuroticism', 'internalization', anxious concerns and traits associated with perfectionism. These factors may play varying roles depending on the specific subdiagnosis of insomnia. In addition, certain personality traits may be related to the response to (cognitive) behavioral treatment. For instance, insomniacs reporting less 'guardedness' and have a higher score on the MMPI 'hypomania' scale show less improvement through psychological treatment. The specific role of personality traits in the etiology of insomnia is not yet clear, because of a lack of longitudinal data. Personality factors may play a causal role in the development of insomnia, but may also be a consequence of the sleep problem and the associated daytime dysfunction. Future longitudinal studies should not view personality as a single predisposing factor, but assess it as a part of a larger group of interacting psychological and physiological factors involved in the predisposition to and perpetuation of chronic insomnia.

Hyperarousal and insomnia: state of the science

In the past few years it has become increasingly clear that insomnia is a chronic disease that interacts with many other medical conditions. As our ability to examine complex physiological activity during sleep has increased, additional evidence continues to suggest that insomnia is associated with inappropriate physiological arousal. It is now known that patients with primary insomnia have increased high-frequency EEG activation, abnormal hormone secretion, increased whole body and brain metabolic activation, and elevated heart rate and sympathetic nervous system activation during sleep. This activation can be measured throughout the day and night and is chronic. Other research suggests that insomnia, probably based upon the associated chronic physiologic arousal, is associated with increased risk for medical disorders such as depression, hypertension, or cardiac disease. An animal model that has used odor stress to produce poor sleep in rats has identified specific activated brain sites similar to those found in human brain metabolic studies to suggest that insomnia is a state in which sleep and arousal systems are both simultaneously active. The animal studies have also shown that the inappropriate arousal can be blocked by lesions in the limbic and arousal systems. It is hoped that these findings can be extended to identify new compounds that improve insomnia by acting at these sites of abnormal brain activation.

The hyperarousal model of insomnia: a review of the concept and its evidence

Primary insomnia is defined as difficulties in falling asleep, maintaining sleep or non-restorative sleep accompanied by significantly impaired daytime functioning in the absence of a specific physical, mental or substance-related cause. The current review provides substantial support for the concept that hyperarousal processes from the molecular to the higher system level play a key role in the pathophysiology of primary insomnia. Autonomous, neuroendocrine, neuroimmunological, electrophysiological and neuroimaging studies demonstrate increased levels of arousal in primary insomnia during both night and daytime. In the light of neurobiological theories of sleep-wake regulation, primary insomnia may be conceptualized as a final common pathway resulting from the interplay between a genetic vulnerability for an imbalance between arousing and sleep-inducing brain activity, psychosocial/medical stressors and perpetuating mechanisms including dysfunctional sleep-related behavior, learned sleep preventing associations and other cognitive factors like tendency to worry/ruminate.

Heart rate variability and daytime functioning in insomniacs and normal sleepers: preliminary results

OBJECTIVES

This study examined the differences in heart rate variability (HRV) and daytime functioning between insomniacs and normal sleepers.

METHODS

All participants underwent an interview, a medical examination, and a sleep measurement protocol during which they wore an actigraph and logged a sleep diary for a 7-day period to verify their eligibility. Included in the study were 18 insomniacs and 21 normal sleepers. During a laboratory session, these participants completed four paper-pencil tests of sleepiness, anxiety, fatigue, and concentration difficulty and the Wisconsin Card Sorting Test. Resting HRV was recorded under paced breathing.

RESULTS

Neither did insomniacs experience cognitive impairment nor did they experience excessive daytime sleepiness compared with normal sleepers. However, insomniacs experienced higher frequency of fatigue [effect size (ES)=1.14, P=.002] compared with normal sleepers. There was also a trend toward higher trait anxiety score (ES=0.62) and concentration difficulty (ES=0.59) in insomniacs than in normal sleepers. Although a tendency toward lower resting high- frequency (HF) HRV (ES=-0.57) in insomniacs than in normal sleepers was noted, neither the resting low-frequency (LF) HRV nor the LF/HF ratio were different between groups. Subjective sleep estimates correlated to self-reported daytime consequences such as fatigue and concentration difficulty but not cognitive function. On the contrary, objective sleep estimates correlated to problem-solving/conceptualization and learning but not self-reported daytime consequences.

CONCLUSIONS

Insomniacs are not sleepier during the day than normal sleepers. However, they may experience such a daytime symptom as fatigue although cognitive function remains unimpaired.

Daytime symptoms in primary insomnia: a prospective analysis using ecological momentary assessment

OBJECTIVES

To prospectively characterize and compare daytime symptoms in primary insomnia (PI) and good sleeper control (GSC) subjects using ecological momentary assessment; to examine relationships between daytime symptom factors, retrospective psychological and sleep reports, and concurrent sleep diary reports.

METHODS

Subjects included 47 PI and 18 GSC. Retrospective self-reports of daytime and sleep symptoms were collected. Daytime symptoms and sleep diary information were then collected for 1 week on hand-held computers. The Daytime Insomnia Symptom Scale (DISS) consisted of 19 visual analog scales completed four times per day. Factors for the DISS were derived using functional principal components analysis. Nonparametric tests were used to contrast DISS, retrospective symptom ratings, and sleep diary results in PI and GSC subjects, and to examine relationships among them.

RESULTS

Four principal components were identified for the DISS: Alert Cognition, Negative Mood, Positive Mood, and Sleepiness/Fatigue. PI scored significantly worse than GSC on all four factors (p<0.0003 for each). Among PI subjects DISS scales and retrospective psychological symptoms were related to each other in plausible ways. DISS factors were also related to self-report measures of sleep, whereas retrospective psychological symptom measures were not.

CONCLUSIONS

Daytime symptom factors of alertness, positive and negative mood, and sleepiness/fatigue, collected with ecological momentary assessment, showed impairment in PI versus GSC. DISS factors showed stronger relationships to retrospective sleep symptoms and concurrent sleep diary reports than retrospective psychological symptoms. The diurnal pattern of symptoms may inform studies of the pathophysiology and treatment outcome of insomnia.

Insomnia: pathophysiology and implications for treatment

Interest in developing a greater understanding of the pathophysiogical mechanisms underlying primary insomnia has increased. Recent evidence indicates that there may be some neuroendocrine and clinical similarities between primary insomnia and major depressive disorder, that abnormal corticotropin releasing factor (CRF) activity occurs in major depression, and that CRF hyperactivity appears to mediate the hyperarousal seen in primary insomnia. These findings all point to the possibility of hypothalamic-pituitary-adrenal (HPA) axis and CRF overactivity in both disorders. More recent findings have strengthened the evidence that primary insomnia may be linked with mood disorders and is associated with HPA axis overactivity and excess secretion of CRF, adrenocorticotropin releasing hormone, and cortisol. These insights have implications for managing chronic primary insomnia, such as use of antiglucocorticoid agents.

Insomnia subtypes and their relationships to daytime sleepiness in patients with obstructive sleep apnea

BACKGROUND

Insomnia and obstructive sleep apnea syndrome (OSA) are the two most common sleep disorders. Studies showed that insomnia complaints were prevalent in OSA. Relatively little is known about the causes of insomnia in OSA and whether etiological factors differ for insomnia subtypes. We hypothesized that sleep onset problem was mainly due to hyperarousal and sleep maintenance difficulty was primarily related to sleep-disordered breathing.

OBJECTIVES

To determine the prevalence of insomnia subtypes in OSA, compare subjects with sleep onset insomnia, sleep maintenance insomnia and no insomnia symptom, and study the relationship of insomnia subtypes to daytime sleepiness.

METHODS

We analyzed intake questionnaires and polysomnography and Multiple Sleep Latency Test results of 157 OSA patients.

RESULTS

Forty-two percent of the sample had at least one problematic insomnia symptom. The prevalence of sleep onset insomnia, sleep maintenance insomnia and insomnia with early awakening was 6, 26 and 19%, respectively. Patients with sleep onset insomnia had significantly lower apnea-hypopnea (AHI) and arousal indices. There were significant inverse relationships between sleep onset insomnia and measures of daytime sleepiness. On the contrary, subjects with repeated wakening had more severe subjective sleepiness. Results were similar in patients with AHI >or=5 or >or=15.

CONCLUSIONS

Insomnia symptoms were common in OSA patients. Insomnia subtypes related differently to measures of daytime sleepiness. Our findings suggest that OSA patients with sleep onset insomnia may be in a state of hyperarousal. It is clinically relevant to examine insomnia subtypes, which may influence the treatment decision in sleep-disordered breathing.

Self-reported sleep duration in Finnish general population

Self-reported short or long sleep duration has been repeatedly found to be associated with increased mortality and health risks. However, there is still an insufficient amount of detailed knowledge available to characterize the short and long sleep duration groups in general population. Consequently, the underlying mechanisms potentially explaining the health risks associated with short and long sleep duration are unclear. In the present study, the self-reported sleep duration in a sample of Finnish general population was studied, and its possible associations with such factors as self-perceived health, sociodemographic characteristics, lifestyle, sleep difficulties and daytime concomitants were analyzed. In particular, an effort was made to define mutually statistically-independent determinants of sleep duration. In the Finnish Health 2000 Survey, a representative sample of 8,028 subjects of 30 years of age or older and a sample of 1,894 subjects of 18-29 years of age were invited to take part in the health interview and health examination. The participation rate of the study was over 80%. The most important and statistically-independent determinants of short and long sleep duration were gender, physical tiredness, sleep problems, marital status, main occupation and physical activity. However, in the multivariable model they only accounted for approximately 16% of the variance in sleep duration in short and long sleepers, suggesting multiple sources of variance. The present study also suggests a dose-response like relationship between the sleep duration and many of its determinants within both short and long sleepers. A more detailed analysis of the clinical status of the short and long sleep duration groups is needed to evaluate the possible importance of these findings for health risks associated with sleep duration.

Efficacy and safety of zolpidem-MR: a double-blind, placebo-controlled study in adults with primary insomnia

BACKGROUND AND PURPOSE

To evaluate the clinical efficacy and safety of modified-release zolpidem (zolpidem-MR 12.5mg) for the treatment of primary insomnia in adults.

PATIENTS AND METHODS

Two hundred and twelve (123 women, 89 men; mean age 44.3+/-SD 3.0 years), Diagnostic and Statistical Manual of Mental Disorders--4th Edition (DSM-IV)-defined primary insomnia patients were randomized in a double-blind, placebo-controlled, parallel-group study. The study was completed by 192 patients. Patients received 3 weeks of nightly treatment with either zolpidem-MR 12.5mg or placebo, preceded and followed by two nights of single-blind placebo. The main outcome measures were mean polysomnographic (PSG) sleep parameters of nights 1/2 and nights 15/16 of double-blind treatment and daily subjective sleep estimates from sleep questionnaires to assess efficacy, and PSG parameters of nights 22 and 23 of single-blind placebo substitution to assess the effect of drug discontinuation.

RESULTS

Relative to placebo, zolpidem-MR 12.5mg improved sleep maintenance by significantly reducing PSG wake time after sleep onset (WASO) during the first 6h of sleep as well as the number of awakenings. Consistent with the effects of standard zolpidem, zolpidem-MR also significantly reduced latency to persistent sleep, and significantly increased sleep efficiency, both at the beginning and after 2 weeks of double-blind treatment. There was no evidence of next-day residual effects as measured objectively by psychometric tests. Rebound insomnia on the first night after abrupt discontinuation resolved the following night. Overall, zolpidem-MR was well tolerated.

CONCLUSIONS

Zolpidem-MR 12.5mg is effective and safe in treating primary insomnia in adults and improves sleep maintenance, induction and duration of sleep.

Sleep homeostasis in primary insomnia

Three main factors, hyperarousal, circadian dysrhythmia, and homeostatic dysregulation, are thought to underlie chronic insomnia. To date, most of the empirical work has focused on the issue of hyperarousal and very little work has been undertaken on the issue of sleep homeostasis. In the present paper, we review the five lines of evidence which may be used to support the proposition that sleep homeostasis is altered in Primary Insomnia. These include findings pertaining to Slow Wave Sleep density, level of daytime sleepiness, sleepiness following sleep deprivation, recovery sleep following sleep deprivation, and response to sleep restriction therapy. In addition, we provide a discussion regarding how hyperarousal and circadian factors may interact with altered sleep homeostasis, and suggestions for further inquiry.

ACNS Clinical Controversy: MSLT and MWT Have Limited Clinical Utility

The Multiple Sleep Latency Test (MSLT) and the Maintenance of Wakefulness Test (MWT) are two commonly used laboratory-based objective tests to measure sleepiness and alertness, respectively. Data suggest both are extremely sensitive tests when measuring the effects of sleep deprivation within subjects, but are less sensitive for confirming sleepiness and response to treatment in groups of patients with different sleep disorders. Inconsistent and even sometimes paradoxical test results may be partly explained by data that show the MSLT and MWT are not selectively sensitive to either sleepiness or alertness, but sensitive to both the sleep and the arousal systems. Sleep latencies seen on both the MSLT and MWT are affected to varying degrees by a myriad of internal and external influences that can alter what we would prefer each test to show. If we continue to use these tests to measure sleepiness or alertness in patients with different sleep disorders, we need to understand more about the nature and impact of different sources of internal and external arousal so that we can better control the test environment. Improved understanding of the determinants of sleep onset is essential because excessive sleepiness has important consequences for both individuals and society.

Chronic insomnia and performance in a 24-h constant routine study

Insomniacs report daytime functioning problems, but studies of neurobehavioral functioning in insomniacs have shown little objective evidence of impairment. In addition, very little is known about the influence of the circadian clock on performance in chronic insomniacs. In the present study, we investigated whether chronic insomnia is associated with an overall performance deficit, and what the effect is of circadian rhythmicity, under strictly controlled laboratory conditions. A 24-h experiment was carried out under constant routine conditions. Psychomotor performance, body temperature, and subjective functioning of 11 insomniacs and 13 healthy subjects were assessed. The insomniacs showed significant overall performance impairments in vigilance, working memory, and motor control. In addition, body temperature, performance and subjective functioning showed a circadian pattern similar to healthy subjects, with trough values in the late night/early morning and peak values in the early evening. Self-reported functioning among the insomniacs indicated mood disturbances, concentration problems, elevated fatigue and elevated sleepiness. The results indicated that chronic insomnia is associated with a substantial lowering of the 24-h level of performance and subjective functioning, irrespective of the type of task and/or the particular parameter, and without differential effects of circadian rhythmicity. Apparently, chronic insomnia has a negative impact upon performance as measured under strictly controlled, unmasked conditions.

A pilot study of subjective daytime alertness and mood in primary insomnia participants using ecological momentary assessment

This pilot study compared daytime symptom ratings in primary insomniacs (n = 7) and age-matched controls (n = 8). Participants completed sleep diaries and rated their daytime symptoms using a Daytime Symptom Diary (DSD) 4 times per day for 1 week. DSD responses were collapsed into 4 domains: mood, subjective alertness, energy, and concentration. The level and variability of DSD domains, and correlations between the domains and sleep diary characteristics, were examined. Significant Group x Time of Day interactions were observed in values for each DSD domain, with the most consistent group differences occurring in the morning. Coefficients of variation for DSD domains were greater in the insomnia group. Frequent measures of daytime symptoms may be useful outcomes in insomnia studies.

CAP variables and arousals as sleep electroencephalogram markers for primary insomnia

OBJECTIVE

Polysomnographic (PSG) measures consistently reflect poor sleep quality and effective treatment in insomniac patients.

METHODS

The PSG findings of 47 patients (18 M and 29 F, 42.5+/-10 years) meeting the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for a diagnosis of primary insomnia were compared with those of 25 age- and gender-balanced healthy subjects (controls) without sleep complaints. After one adaptation night to the sleep lab, each patient underwent two randomized double-blind PSG recordings. Twenty-four patients followed a placebo-drug sequence and 23 a drug-placebo succession. Active treatment consisted of widely used hypnotic drugs, i.e. zolpidem, triazolam, zopiclone, brotizolam. Conventional PSG measures, electroencephalogram (EEG) arousals and CAP variables (including phase A subtypes) were quantified and statistically analyzed.

RESULTS

Compared to controls, insomniac patients under placebo showed a significant increase of CAP rate, subtypes A1 and A2, EEG arousals, nocturnal wakefulness and stage 1, associated with reduced values of total sleep time and slow wave sleep (stages 3 and 4). In insomniac patients, sleep quality was significantly improved by hypnotic treatment. Compared to placebo, active medication significantly reduced CAP rate, subtypes A1 and A2, but had only marginal effects on subtypes A3 and on EEG arousals. Under hypnotic treatment total sleep time, nocturnal awakenings, stage 1 and slow wave sleep recuperated normal values. The most significant correlation between sleep quality and PSG variables was found for CAP rate (P<0.0001).

CONCLUSIONS

PSG investigation extended to CAP variables and EEG arousals can be an important procedure for the diagnosis of primary insomnia and evaluation of treatment efficacy.

Daytime testing after laboratory or home-based polysomnography: comparisons of middle-aged insomnia sufferers and normal sleepers

Many studies have shown only modest differences between insomnia sufferers and matched, non-complaining normal controls in regard to their levels of daytime sleepiness and diurnal performances. The current study was conducted to determine whether such daytime comparisons might be affected by the setting (home vs. sleep lab) in which study participants sleep on the nights before such testing. The study used a counter-balanced, matched-group design in which participants underwent three consecutive nocturnal polysomnographs (PSG) conducted either in the sleep lab or in their homes prior to undergoing daytime multiple sleep latency test (MSLT) and computer-administered performance testing. The study participants were 35 (18 women and 17 men) middle-aged (40-59 years) non-complaining normal sleepers and 33 middle-aged insomnia sufferers (17 women and 16 men) who met structured interview criteria for persistent primary insomnia. Use of a hierarchical linear statistical model showed only insomnia sufferers who underwent nocturnal home PSG were more alert on the MSLT than were normal sleepers who underwent lab PSG. However, these insomnia sufferers showed a greater propensity toward attention lapses on selected reaction time tests than did either of the two normal control groups (i.e. either those who slept in the lab or those who slept at home). The results suggest the nocturnal sleep setting (home vs. lab) may affect subsequent MSLT and performance test comparisons of insomnia sufferers and normal sleepers.

P300 amplitude in subjects with primary insomnia is modulated by their sleep quality

OBJECTIVE

The hyperarousal hypothesis is evaluated while controlling the influence of the quality of sleep in the night preceding the evaluation.

METHOD

Eleven primary insomniacs and 11 healthy age matched controls participated to the study. Participants filled in 2 weeks of sleep logs and self-monitored their subjective tension the evening before and the morning after each night. Afterwards, subjects were called in to the Lab for a recording session of the P300 ERP (oddball paradigm) once after a night of bad sleep quality (N-) and once after a night of good sleep quality (N+).

RESULTS

The main result of the present study indicated that the P300 amplitude at Fz in insomniacs resulted higher following a N- and lower following a N+ with respect to controls.

CONCLUSIONS

This result suggests that cortical hyperarousal in primary insomniacs is not a stable individual characteristic, but is associated with the poor quality of their nocturnal sleep.