Interactions between evening and nocturnal cortisol secretion and sleep parameters in patients with severe chronic primary insomnia

Hypertension and sleep: overview of a tight relationship

Autonomic cardiovascular control changes across sleep stages. Thus, blood pressure (BP), heart rate and peripheral vascular resistance progressively decrease in non-rapid eye movement sleep. Any deterioration in sleep quality or quantity may be associated with an increase in nocturnal BP which could participate in the development or poor control of hypertension. In the present report, sleep problems/disorders, which impact either the quality or quantity of sleep, are reviewed for their interaction with BP regulation and their potential association with prevalent or incident hypertension. Obstructive sleep apnea syndrome, sleep duration/deprivation, insomnia, restless legs syndrome and narcolepsy are successively reviewed. Obstructive sleep apnea is clearly associated with the development of hypertension that is only slightly reduced by continuous positive airway pressure treatment. Shorter and longer sleep durations are associated with prevalent or incident hypertension but age, gender, environmental exposures and ethnic differences are clear confounders. Insomnia with objective short sleep duration, restless legs syndrome and narcolepsy may impact BP control, needing additional studies to establish their impact in the development of permanent hypertension. Addressing sleep disorders or sleep habits seems a relevant issue when considering the risk of developing hypertension or the control of pre-existent hypertension. Combined sleep problems may have potential synergistic deleterious effects.

Physiological correlates of insomnia

Insomnia is a prevalent sleep disorder that is typically comorbid with medical, psychiatric, and other sleep disorders. Yet, it is a disorder with its own course and morbidity that can persist if untreated. This chapter describes the physiological correlates of insomnia expressed during sleep and during the daytime. Together, the data from nighttime and daytime electrophysiology, event-related brain potential recording, neuroimaging studies, sympathetic nervous system, and HPA axis monitoring all suggest that insomnia is a 24 h disorder of hyperarousal.

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.

Common biological pathways underlying the psychoneurological symptom cluster in cancer patients

BACKGROUND

A symptom cluster is a group of symptoms that occur together and are interrelated. The clinical implication of symptom cluster research is to use the clustering patterns of symptoms to understand the mechanisms for these symptoms and develop management strategies targeted at multiple symptoms.

OBJECTIVE

The purposes of this review were to summarize the evidence for a psychoneurological symptom cluster in cancer patients, to provide information regarding the underlying biological mechanisms for each of the psychoneurological symptoms within the cluster, and to propose possible common biological pathways that may underlie this cluster.

METHODS

A systematic review of the literature was conducted.

RESULTS

Empirical evidence exists to support a cluster of psychoneurological symptoms (ie, depressive symptoms, cognitive disturbance, fatigue, sleep disturbance, pain). At a molecular level, common biological pathways (ie, proinflammatory cytokines, hypothalamic-pituitary-adrenal axis, and monoamine neurotransmission system) may underlie the development of symptoms within this cluster. Activation of proinflammatory cytokines is proposed as a first stage of mechanistic pathway. However, other biological factors, such as lowered estrogen or hemoglobin levels, may influence psychoneurological cluster.

CONCLUSION

Additional studies are needed to confirm the roles of cytokines as well as other biological factors in the development of the psychoneurological cluster and to determine the biomarkers to identify the subgroups of cancer patients who are at greatest risk for this cluster.

IMPLICATIONS FOR PRACTICE

This information can be used by researchers and clinicians to guide the selection of symptom management strategies that are ideally targeted to the biological mechanisms that underlie this symptom cluster.

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.

Alterations in hypothalamus-pituitary-adrenal/thyroid axes and gonadotropin-releasing hormone in the patients with primary insomnia: a clinical research

The hypothalamus-pituitary-target gland axis is thought to be linked with insomnia, yet there has been a lack of further systematic studies to prove this. This study included 30 patients with primary insomnia (PI), 30 patients with depression-comorbid insomnia (DCI), and 30 healthy controls for exploring the alterations in the hypothalamus-pituitary-adrenal/thyroid axes’ hormones and gonadotropin-releasing hormone (GnRH). The Pittsburgh Sleep Quality Index was used to evaluate sleep quality in all subjects. The serum concentrations of corticotrophin-releasing hormone (CRH), thyrotrophin-releasing hormone (TRH), GnRH, adrenocorticotropic hormone (ACTH), thyroid stimulating hormone (TSH), cortisol, total triiodothyronine (TT3), and total thyroxine (TT4) in the morning (between 0730 h and 0800 h) were detected. Compared to the controls, all hormonal levels were elevated in the insomniacs, except ACTH and TSH in the PI group. Compared to the DCI patients, the PI patients had higher levels of CRH, cortisol, TT3, and TT4 but lower levels of TRH, GnRH, and ACTH. Spearman’s correlation analysis indicated that CRH, TRH, GnRH, TSH, cortisol, TT4, and TT3 were positively correlated with the severity of insomnia. The linear regression analysis showed that only CRH, GnRH, cortisol, and TT3 were affected by the PSQI scores among all subjects, and only CRH was included in the regression model by the “stepwise” method in the insomnia patients. Our results indicated that PI patients may have over-activity of the hypothalamus-pituitary-adrenal/thyroid axes and an elevated level of GnRH in the morning.

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.

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.

The prevalence of impaired glucose regulation in psychiatric patients with sleep disorders and its relationship with altered hypothalamopituitary-adrenal and hypothalamopituitary-thyroid axis activity

BACKGROUND

Sleep restriction, an important symptom of psychiatric diseases, is associated with adverse effects on glucose regulation, but few studies have examined its association with impaired glucose regulation and altered hypothalamic activity. Our study was designed to evaluate the sleep duration, fasting glucose, tolerance glucose, and concentration of plasma insulin; to assess the function of both the hypothalamopituitary-thyroid (HPT) and hypothalamopituitary-adrenal (HPA) axis; and to investigate the relationship of altered hypothalamic function with glucose metabolism in psychiatric patients with a sleep disorders.

METHODS

From January 2010 to December 2011, 324 women (64.7%) and 177 men (35.32%) with a diagnosis of a sleep disorder participated in our cross-sectional study in the psychiatric outpatient department of the West China Hospital of Sichuan University. Results from 75-g glucose tolerance tests, insulin-releasing tests, morning (8:00 am) serum cortisol, and thyroid-stimulating hormone (TSH) (TT3, TT4, FT3, FT4) were collected, as well as body mass index and waist-hip ratio to assess the prevalence of impaired glucose regulation and function of the HPA and HPT axis. Sleep quality was assessed through self-reported questionnaires.

RESULTS

There were 301 patients previously diagnosed with an anxiety disorder (78%), and 200 patients previously diagnosed with depression and other psychiatric diseases (22%). Crude prevalence rates were 15.0% for diabetes mellitus (DM), 11.6% for impaired glucose tolerance, 15.8% for impaired fasting glucose, and 11.6% for impaired glucose regulation (impaired glucose tolerance [IGT]+impaired fasting glucose [IFG]). Total prevalence of impaired glucose regulation in patients with a sleep disorder was 48.8%. Mean cortisol level was 463.5±178.8 nmol/L, and the cortisol concentration at 8:00 am was significantly associated with a higher prevalence of impaired glucose regulation and insulin resistance. TSH values above 2.5 mU/L accounted for over 58% and were significantly associated with insulin resistance.

CONCLUSIONS

These results partially confirm that a high level of cortisol and an increased activity of the HPT axis are associated with impaired glucose regulation. Therefore, as a pathophysiologic event abnormal activity of the hypothalamic function of psychiatric patients with sleep disorders could be viewed as a potential risk factor for increasing incidence of DM.

Excitatory versus inhibitory impairments in insomnia patients: an ERP study

According to the neurocognitive perspective on insomnia, conditioned arousal results in impairment of information processing, as such interfering with normal sleep processes. In the present study, evening event-related potentials N100 and P200 were evaluated to assess hyperarousal in patients with insomnia and controls. 13 patients (mean age = 40.8) with polysomnographically verified sleep disruptions and 11 good sleepers (mean age = 45.4) were included. An auditory oddball paradigm was administered the evening of the polysomnography. N100 and P200 mean amplitudes and peak latencies at Fz and Cz were analyzed as a measure of respectively general arousability and inhibition of information processing. Patients experiencing insomnia were characterized by decreased P200 amplitudes compared to good sleepers. No significant differences were found for N100 amplitudes and latencies of both ERP waves. These results suggest that this group of patients with objectified insomnia is characterized by an arousal impairment. However, there was no evidence of hyperarousal, considering the normal N100 amplitudes. On the other hand, the inhibition of information processing was distorted. As such, the impairment of de-arousal or de-activation in insomnia is put forward as an additional factor within the arousal model.

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 duration buffers diurnal cortisol increases in older adulthood

This study examined the long-term associations between reports of sleep duration and diurnal cortisol secretion in older adulthood. It was hypothesized that longer sleep would protect older adults against increases in diurnal cortisol secretion over time. We tested this hypothesis using three waves of data from a 4-year longitudinal study involving 157 older adults. Results from growth curve and cross-lagged panel analyses demonstrated that levels and increases in sleep duration buffered long-term elevations of diurnal cortisol secretion. Reversed analyses indicated that diurnal cortisol secretion did not predict changes in sleep duration over time. These results were independent from sociodemographic characteristics (i.e., age, sex, partnership status, and education) and health-related variables (i.e., chronic illness, medication usage, body mass index, and smoking). They suggest that long sleep exerts restorative functions and protects older adults from exhibiting increases in diurnal cortisol secretion over time.

Sleep and inflammation: psychoneuroimmunology in the context of cardiovascular disease

BACKGROUND

Poor sleep is prospectively linked to all-cause and cardiovascular mortality. Inflammatory processes may be an important biological mechanism linking poor sleep to cardiovascular disease. Such processes involve active participation of signaling molecules called cytokines in development of atherosclerotic plaques.

PURPOSE

I review evidence from experimental sleep deprivation and clinical observational studies suggesting a bidirectional relationship between sleep and inflammatory cytokines.

RESULTS

Findings from sleep deprivation studies indicate that sleep loss is associated with increases in these cytokines. Similarly, studies in clinical populations with sleep problems, such as primary insomnia patients and those diagnosed with major depression, also show elevations in these same cytokines.

CONCLUSIONS

Bidirectional communication between the brain and the immune system is carried out through a complex network of autonomic nerves, endocrine hormones, and cytokines. Disturbed sleep appears to perturb the functioning of this network and therefore contribute to elevations in inflammatory mediators linked to cardiovascular disease.

[Biological principles of sleep and wake]

Electrophysiologically measurable sleep is divided into rapid eye movement (REM) sleep and nonREM sleep--the latter is further structured into several sleep stages, including deep sleep. This internal sleep regulation is explained by the reciprocal interaction model that was validated in 1975. The interdependence of not only the reciprocal discharge of cholinergic REM-on, but also serotonergic and noradrenergic (REM-off) cell populations distributed over the brain stem results in the alternating pattern of nonREM and REM sleep. The timing of sleep onset and waking is described using the two-process model. Thereby, the theoretical sum of all circadian processes (process C) interacts with the homeostatic sleep drive (process S). Because the occurrence of REM sleep also depends on circadian factors, the decrease of deep sleep during the night is accepted as a physiological correlate of process S. Social activity and daylight synchronize the circadian process with the external 24-h day. With the help of the orexin system, the flip-flop model explains why both sleep and wake can be sustained over longer periods. Dependency on age and physiological short and long sleepers are the most prominent variations of normal sleep behavior. Newer therapeutic concepts in sleep medicine have taken into consideration these biological basics, e.g., in the selection of sleep medication and in the development of new sleep-inducing medications.

A meta-analysis of electroencephalographic sleep in depression: evidence for genetic biomarkers

BACKGROUND

Research on whether any electroencephalographic (EEG) sleep abnormalities observed among individuals with major depressive disorder (MDD) represent genetic biomarkers remains inconclusive. We aimed to identify EEG-based biomarkers of MDD through a review of studies from three populations: individuals with MDD, individuals with MDD under remission, and never depressed high-risk probands (HRPs) of individuals with MDD.

METHODS

We searched databases such as MEDLINE and PsycINFO for EEG studies published since 1970. Of the 886 records, our selection criteria identified 56 studies that employed standardized EEG scoring procedures and addressed confounds such as participant reactivity and drug effects. We then used fixed-effects models to calculate average weighted mean differences in EEG parameters between clinical groups across these studies.

RESULTS

Individuals with MDD differed significantly from control subjects on several EEG variables. However, remitted individuals showed normalization of all affected EEG parameters except rapid eye movement (REM) density and slow-wave sleep (SWS). Surprisingly, proportion of SWS was significantly shorter during remission than depression. Never-depressed HRPs also exhibited significantly elevated REM density and reduced SWS. Finally, these parameters constituted the only two EEG variables that were not moderated by depression severity.

CONCLUSIONS

Individuals experiencing MDD and those in remission exhibit increased REM density and shortened SWS, as do HRPs with no history of MDD. Thus, this combination of EEG features may represent a genetic biomarker of MDD. Further, SWS appears to be shorter during remission than depression, suggesting its role as both a genetic marker as well as a biological scar of the disorder.

The stress hormone system in various sleep disorders

Hypothalamic-pituitary-adrenal (HPA)-system activity is regulated by the suprachiasmatic nucleus, the primary endogenous circadian pacemaker. In addition, sleep plays an important modulatory role. However, data on HPA-system activity in sleep disorders are quite conflicting. A sensitive challenge test to assess negative feedback sensitivity of the HPA-system like the dexamethasone/corticotropin-releasing-hormone (DEX/CRH)-test has never been used so far in sleep disorders. Therefore we studied 25 obstructive sleep apnea (OSA) patients, 18 restless legs syndrome (RLS) patients, 21 patients with primary insomnia and compared them to 33 healthy controls. The dynamic response of the HPA-system was assessed by the DEX/CRH-test which combines suppression (dexamethasone) and stimulation (CRH) of the stress hormone system. After HPA-axis suppression the number of non-suppressors did not differ among groups indicating normal negative feedback sensitivity. In RLS patients ACTH levels were slightly lower compared to controls while cortisol levels were similar between groups. Following CRH stimulation we did not detect differences in ACTH- or cortisol levels and adrenocortical responsitivity to ACTH was comparable between groups. These results for the first time document normal HPA-system feedback sensitivity in various sleep disorders and suggest that abnormalities of the stress hormone system in affective disorders are unlikely due to concomitant sleep problems.

Sleep onset and cardiovascular activity in primary insomnia

The transition from wakefulness to sleep is characterized typically by a shift from sympathetic to parasympathetic regulation. Physiological functions, depending on the neurovegetative system, decrease overall. Previous studies have shown cardiovascular and electroencephalographic hyperactivity during wakefulness and sleep in insomniacs compared with normal sleepers, but there is very little evidence of this in the process of sleep onset. The purpose of this study was to compare cardiovascular and autonomic responses before and after falling asleep in eight insomniacs (who met DSM-IV criteria for primary insomnia) and eight normal sleepers. Non-invasive measures of heart rate (HR), stroke volume (SV), cardiac output (CO) and pre-ejection period (PEP) were collected by impedance cardiography during a night of polysomnographic recording. Frequency domain measures [low-frequency (LF), high-frequency (HF)] of heart rate variability (HRV) were also estimated. Decrements in HR and CO and increases in SV and HF normalized units (n.u.) were found in both groups after sleep onset compared with wakefulness. Conversely, PEP (related inversely to sympathetic β-adrenergic activity) showed increases after sleep onset in controls, but remained unchanged in insomniacs. PEP was also significantly lower in insomniacs than in normal sleepers in both conditions. These data suggest that, whereas normal sleepers follow the expected progressive autonomic drop, constant sympathetic hyperactivation is detected in insomniacs. These results support the aetiological hypothesis of physiological hyperarousal underlying primary insomnia.

Neuromedin U(2) receptor signaling mediates alteration of sleep-wake architecture in rats

Growing evidence indicates that neuromedin U (NmU) neuropeptide system plays an integral role in mediating the stress response through the corticotrophin-releasing factor (CRF) pathways. Stress is often associated with alteration in sleep-wake architecture both in human and laboratory animals. Here, we investigated whether activation of the NmU₂ receptor, a major high affinity receptor for NmU predominantly expressed in the brain, affects sleep behavior in rats. Effects of single (acute) intracebroventricular (icv) infusion of 2.5 nmol of the full agonists porcine NmU8 and rat NmU23 were assessed on sleep-wake architecture in freely moving rats, which were chronically implanted with EEG and EMG electrodes. In addition, repeated once daily administration of NmU8 at 2.5 nmol during 8 consecutive days (sub-chronic) was studied. Acute icv infusion of NmU23 elicited a robust alteration in sleep-wake architecture, namely enhanced wakefulness and suppressed sleep during the first 4h after administration. Acute infusion NmU8 had no effect on spontaneous sleep-wake architecture. However, sub-chronic icv infusion of NmU8 increased the amount of rapid eye movement (REM) sleep and intermediate stage (IS), while decreased light sleep. Additionally, NmU8 increased transitions from sleep states towards wakefulness suggesting a disruption in sleep continuity. The present results show that central-activation of NmU₂ receptor markedly reduced sleep duration and disrupted the mechanisms underlying NREM-REM sleep transitions. Given that sleep-wakefulness cycle is strongly influenced by stress and the role of NmU/NmU₂ receptor signaling in stress response, the disruption in sleep pattern associated with peptides species may support at least some signs of stress.

Do sleep complaints contribute to age-related cognitive decline?

The cognitive changes that occur with ageing are usually referred to as 'age-related cognitive decline'. The most pronounced changes may be found in the executive functions that require integrity of the prefrontal cortical circuitry. With age, sleep also changes profoundly, with more sleep fragmentation, earlier awakenings and less slow wave sleep as its main features. Interestingly, experimental sleep deprivation studies in healthy young adults showed a particularly consistent effect on executive functions, suggesting that sleep problems might contribute to the cognitive changes accompanying older age. We here investigate this possibility by reviewing reports on age-related and insomnia-related changes in cognition and brain function and structure, as found in studies investigating subjective complaints, objective functioning in everyday life, neuropsychological assessment, psychometry, structural and functional magnetic resonance imaging, electroencephalography, positron emission tomography and transcranial magnetic stimulation. The chapter focuses on the 'normal' age-related sleep changes that are experienced as insomnia - that is, fragmentation of sleep, more superficial sleep, more wake after sleep onset and earlier awakenings - rather than on specific sleep disturbances as sleep-disordered breathing, restless legs or periodic limb movements during sleep, for all of which the risk increases with age. It turned out that relatively few studies directly addressed the question whether elderly with different degrees of sleep complaints are differentially affected by 'age-related cognitive decline'. Still, several similarities between age-related and insomnia-related cognitive and brain changes are apparent, notably with respect to performance requiring integrity of the prefrontal cortical system. We suggest that at least part of what we regard as age-related changes may, in fact, be due to poor sleep, which is in some cases a treatable condition. Further research directly comparing aged good sleepers versus aged insomniacs will need to elucidate how sleep disturbances are involved in the cognitive, structural and functional changes observed with increasing age. The findings suggest that discrimination of subtypes of poor sleep at high age will aid in understanding the mechanisms by which it affects cognition and brain function.

Cognitive performance and cardiovascular markers of hyperarousal in primary insomnia

The purpose of the present study was to assess differences in cardiovascular activity and cognitive performance between insomniacs and good sleepers. Sixteen undergraduates participated in the study, eight insomniacs (age 22.9 ± 2.4) enrolled in accord with DSM-IV criteria for primary insomnia, and eight good sleepers (24.8 ± 2.7) were controls. The task employed, Stop Signal Task, assesses motor inhibition processes and was administered in two sessions, before and after a night of polysomnographic recording. During task performance, cardiovascular measures such as heart rate (HR), stroke volume (SV), cardiac output (CO), pre-ejection period (PEP) and left ventricular ejection time (LVET) were continuously recorded by means of impedance cardiography. Performance results showed prolonged Stop Signal Delay (SSD) in the morning in both groups and slower Stop Signal Reaction Time (SSRT) in insomniacs compared with good sleepers, while no effects were observed for performance accuracy. Analyses performed on cardiovascular parameters revealed higher HR and lower LVET values in the insomnia group as compared to healthy controls in the evening. PEP, an index inversely related to sympathetic beta-adrenergic activity, was continuously reduced in insomniacs, indicating constantly enhanced sympathetic activation. These findings suggest a deficit of motor inhibition control in insomnia, matched with high levels of cardiovascular arousal. Overall, our results support the notion that insomniacs suffer from both cognitive deficits and a hyperarousal disorder affecting somatic activity, that contribute to diurnal complaints often referred in addition to sleep disruption.

Relationship of sleep quantity and quality with 24-hour urinary catecholamines and salivary awakening cortisol in healthy middle-aged adults

OBJECTIVES

a. Explore the stability in sleep/wake patterns of middle-aged adults over a 3-year follow-up period. b. Explore the relationship between objectively measured sleep indices, urinary catecholamines, and salivary cortisol.

DESIGN

Naturalistic follow-up for sleep/wake patterns (n = 114) by 2-week sleep log and cross-sectional design for objective sleep assessments and hormonal measures (n = 96) at follow-up period nearly 3 years after baseline measurements.

SETTING

Community

PARTICIPANTS

Healthy middle-aged adults

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

There were high correlations between baseline and follow-up period (2.6 ± 0.5 years) on sleep/wake patterns (r = 0.6-0.79) as measured by 2-week sleep log. For wave 2 cross-sectional study, objective poor sleepers (3-day actigraphy sleep efficiency < 85%) had a higher 24-h urinary norepinephrine (NE) level (205.7 ± 105 nmol/d vs 162.1 ± 55.6 nmol/d, P = 0.03) and a nearly significantly higher 24-h urinary epinephrine (E) level (P = 0.12) than good sleepers. There were no differences in 3-day mean salivary awakening cortisol and 24-h urinary catecholamines (NE and E) between short and normal/long sleepers. Linear regression results, however, showed that shorter time in bed and actual sleep time, longer sleep onset latency, and lower sleep efficiency were correlated with higher 24-h urinary E and NE (all P < 0.05) but not salivary cortisol. The effect of poor sleep quality on 24-h urinary catecholamines was stronger in males than females.

CONCLUSIONS

Increased sympathetic activity as measured by 24-h urinary catecholamines might play a critical role in the pathogenesis mediating the relationship of insufficient sleep (quantity and quality) with subsequent cardiovascular and metabolic complications. Salivary awakening cortisol was not associated with sleep quantity and quality in healthy middle-aged adults.

Restless legs syndrome: evidence for nocturnal hypothalamic-pituitary-adrenal system activation

Epidemiological studies consistently point to a relationship between restless legs syndrome (RLS) and cardiovascular disease. The mechanism underlying this association is unclear. Activation of the hypothalamic-pituitary-adrenal (HPA) system has been shown to contribute to the metabolic syndrome and an enhanced cardiovascular risk. We investigated cortisol levels as an indicator of HPA system activity in RLS during the nighttime, when RLS symptoms are at their maximum. We assessed nocturnal urinary cortisol excretion in 73 patients with RLS and 34 healthy controls, controlling for age and gender. Urine sampling was paralleled by polysomnographic recordings. We found significantly enhanced nocturnal cortisol excretion in RLS, demonstrating nocturnal HPA system overactivity in RLS. HPA system overactivity is a possible mechanism contributing to the enhanced load of cardiovascular disease in RLS patients. Nocturnal cortisol release showed weak correlations with some polysomnographic parameters of disturbed sleep, making a potential contribution of RLS-induced sleep disruption to HPA system activation conceivable.

An exploratory study on the effects of tele-neurofeedback and tele-biofeedback on objective and subjective sleep in patients with primary insomnia

Insomnia is a sleeping disorder, usually studied from a behavioural perspective, with a focus on somatic and cognitive arousal. Recent studies have suggested that an impairment of information processes due to the presence of cortical hyperarousal might interfere with normal sleep onset and/or consolidation. As such, a treatment modality focussing on CNS arousal, and thus influencing information processing, might be of interest. Seventien insomnia patients were randomly assigned to either a tele-neurofeedback (n = 9) or an electromyography tele-biofeedback (n = 8) protocol. Twelve healthy controls were used to compare baseline sleep measures. A polysomnography was performed pre and post treatment. Total Sleep Time (TST), was considered as our primary outcome variable. Sleep latency decreased pre to post treatment in both groups, but a significant improvement in TST was found only after the neurofeedback (NFB) protocol. Furthermore, sleep logs at home showed an overall improvement only in the neurofeedback group, whereas the sleep logs in the lab remained the same pre to post training. Only NFB training resulted in an increase in TST. The mixed results concerning perception of sleep might be related to methodological issues, such as the different locations of the training and sleep measurements.

Lack of hippocampal volume differences in primary insomnia and good sleeper controls: an MRI volumetric study at 3 Tesla

BACKGROUND

A recent pilot study reported that hippocampal volume (HV) was reduced in patients with primary insomnia (PI) relative to normal sleepers. Loss of HV in PI might be due to chronic hyperarousal and/or chronic sleep debt. The aim of this study was to replicate the earlier pilot report while employing a larger sample, more rigorous screening criteria, and objective sleep data.

METHODS

This cross-sectional design included community recruits meeting DSM-IV criteria for PI (n=20, 10 males, mean age 39.3+/-8.7) or good sleeper controls (n=15, 9 males, mean age 38.8+/-5.3). All subjects were unmedicated and rigorously screened to exclude comorbid psychiatric and medical illness. PI subjects underwent overnight polysomnography to screen for sleep-related breathing and movement disorders. HV and total brain volumes were derived by MRI employing a Siemens/Trio scanner operating at 3 Tesla. Data also included 2 weeks of sleep diaries and wrist actigraphy.

RESULTS

Mean HV was 4322.0+/-299.7 mm(3) for the good sleeper controls and 4601.55+/-537.4 mm(3) for the PI group. The dependent variable, HV, was analyzed by ANCOVA. Main effects were diagnosis and gender; whole brain volume served as the covariate. Although the overall model was significant (F=6.3, p=0.001), the main effects of diagnosis (F=2.14) and gender (F=0.04) were not significant. The covariate of whole brain volume was significant (F=5.74, p=0.023) as was the interaction of diagnosis with gender (F=10.22, p=0.003), with male insomniacs having larger HVs than male controls.

CONCLUSIONS

This study did not replicate a previously published report of HV loss in primary insomnia. Differences between our finding and the previous report might be due to sample composition and method of MRI assessment. Furthermore, we demonstrated no objective differences between the controls and PIs in actigraphic measures of sleep maintenance. Within the PIs, however, actigraphic measures of poor sleep maintenance were associated with smaller HV.

Association between a serotonin transporter length polymorphism and primary insomnia

STUDY OBJECTIVE

To test the hypothesis that a 44-base-pair insertion/deletion polymorphism in the 5' regulatory region of the serotonin transporter gene (5-HTTLPR) is associated with primary insomnia.

DESIGN

Association study.

SETTING

Sleep laboratory at the Central Institute of Mental Health, Mannheim, Germany.

PATIENTS

157 patients with primary insomnia and 827 healthy controls.

INTERVENTIONS

N/A.

MEASUREMENT AND RESULTS

We found the short (s-) allele of the 5-HTTLPR to be significantly more frequent in patients suffering from insomnia than in control individuals (47.1% vs. 39.9%: OR = 1.34).

CONCLUSIONS

This finding contributes to the understanding of the pathophysiology of primary insomnia and suggests a biological basis between the prevalent comorbidity of primary insomnia and other psychiatric disorders.

Sleep actigraphy pattern and behavioral/emotional difficulties in kindergarten children: association with hypothalamic-pituitary-adrenocortical (HPA) activity

BACKGROUND

Various studies of adult endocrinology and sleep show close connections between poor sleep quality, deterioration of the HPA axis and negative psychological characteristics. However, the extent to which these associations may have already emerged and developed in childhood remains unclear.

METHODS

A total of 82 preschoolers (age 4.91+/-0.48) underwent activity monitoring for seven consecutive days and nights, wearing a digital movement-measuring instrument. Additionally, on the first and on the last morning of sleep registration, the activity of the HPA axis was assessed via the amount of cortisol in the saliva. Psychological and behavioral assessments were also made.

RESULTS

Three sub-groups of good (22%), normal (58.5%) and poor (19.5%) sleepers were distinguished. Poor sleep patterns were associated with higher HPA activity and with behavioral/emotional difficulties.

CONCLUSIONS

The interplay between unfavorable sleep patterns, deterioration of the HPA axis and behavioral/emotional difficulties is already apparent in pre-school children.

Effects of sleep deprivation on sleep homeostasis and restoration during methadone-maintenance: a [31]P MRS brain imaging study

Insomnia afflicts many individuals, but particularly those in chronic methadone treatment. Studies examining sleep deprivation (SD) have begun to identify sleep restoration processes involving brain bioenergetics. The technique ([31])P magnetic resonance spectroscopy (MRS) can measure brain changes in the high-energy phosphates: alpha-, beta-, and gamma-nucleoside triphosphate (NTP). In the present study, 21 methadone-maintained (MM) and 16 control participants underwent baseline (BL), SD (40 wakeful hours), recovery1 (RE1), and recovery2 (RE2) study nights. Polysomnographic sleep was recorded each night and ([31])P MRS brain scanning conducted each morning using a 4T MR scanner (dual-tuned proton/phosphorus head-coil). Interestingly, increases in total sleep time (TST) and sleep efficiency index (SEI) commonly associated with RE sleep were not apparent in MM participants. Analysis of methadone treatment duration revealed that the lack of RE sleep increases in TST and SEI was primarily exhibited by short-term MM participants (methadone <12 months), while RE sleep in long-term MM (methadone >12 months) participants was more comparable to control participants. Slow wave sleep increased during RE1, but there was no difference between MM and control participants. Spectral power analysis revealed that compared to control participants; MM participants had greater delta, theta, and alpha spectral power during BL and RE sleep. ([31])P MRS revealed that elevations in brain beta-NTP (a direct measure of ATP) following RE sleep were greater in MM compared to control participants. Results suggest that differences in sleep and brain chemistry during RE in MM participants may be reflective of a disruption in homeostatic sleep function.

Impact of sleep and its disturbances on hypothalamo-pituitary-adrenal axis activity

The daily rhythm of cortisol secretion is relatively stable and primarily under the influence of the circadian clock. Nevertheless, several other factors affect hypothalamo-pituitary-adrenal (HPA) axis activity. Sleep has modest but clearly detectable modulatory effects on HPA axis activity. Sleep onset exerts an inhibitory effect on cortisol secretion while awakenings and sleep offset are accompanied by cortisol stimulation. During waking, an association between cortisol secretory bursts and indices of central arousal has also been detected. Abrupt shifts of the sleep period induce a profound disruption in the daily cortisol rhythm, while sleep deprivation and/or reduced sleep quality seem to result in a modest but functionally important activation of the axis. HPA hyperactivity is clearly associated with metabolic, cognitive and psychiatric disorders and could be involved in the well-documented associations between sleep disturbances and the risk of obesity, diabetes and cognitive dysfunction. Several clinical syndromes, such as insomnia, depression, Cushing's syndrome, sleep disordered breathing (SDB) display HPA hyperactivity, disturbed sleep, psychiatric and metabolic impairments. Further research to delineate the functional links between sleep and HPA axis activity is needed to fully understand the pathophysiology of these syndromes and to develop adequate strategies of prevention and treatment.

Self-reported sleep duration and sleep disturbance are independently associated with cortisol secretion in the Whitehall II study

CONTEXT

The association of short sleep duration with cortisol secretion has not been thoroughly examined in large community dwelling populations and the relative importance of short sleep duration and sleep disturbance is unclear.

OBJECTIVE

The objective of the study was to assess the relationships between self-reported sleep duration, sleep disturbance, and salivary cortisol secretion.

DESIGN

This was a cross-sectional analysis using data from phase 7 (2002-2004) of the Whitehall II study. Sleep disturbances were assessed using a modified version of the Jenkins Scale.

SETTING

The occupational cohort was originally recruited in 1985-1989.

PARTICIPANTS

Analyses included 2751 participants with complete cortisol measures and who collected their first sample within 15 min of waking, were not on medication affecting cortisol secretion, and had complete information for all covariates.

OUTCOME MEASURE

Six saliva samples were taken on waking, waking + 0.5, 2.5, 8, and 12 h and bedtime for the assessment of the cortisol awakening response and the slope in cortisol secretion across the day.

RESULTS

In mutually adjusted analyses, both sleep duration and disturbances were independently associated with a flatter diurnal slope in cortisol secretion, such that evening cortisol secretion was raised in those reporting short sleep duration and high sleep disturbance. Short sleep duration was also associated with the cortisol awakening response. These effects were independent of a number of covariates, including waking time on day of sampling and stress on the day of cortisol assessment.

CONCLUSION

Short sleep duration and increased sleep disturbances are independently associated with diurnal slope in cortisol secretion of a large community-based cohort of middle-aged men and women.

Comorbidity of insomnia and depression

During the last decade, several studies have shown that insomnia, rather than a symptom of depression, could be a medical condition on its own, showing high comorbidity with depression. Epidemiological research indicates that insomnia could lead to depression and/or that common causalities underlie the two disorders. Neurobiological and sleep EEG studies suggest that a heightened level of arousal may play a common role in both conditions and that signs of REM sleep disinhibition may appear in individuals prone to depression. The effects of antidepressant drugs on non-REM and REM sleep are discussed in relation to their use in insomnia comorbid with depression. Empirical treatment approaches are behavioral management of sleep combined with prescription of a sedative antidepressant alone, co-prescription of two antidepressants, or of an antidepressant with a hypnotic drug.

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.

Comorbidity between sleep apnea and insomnia

The association between insomnia and sleep apnea has received little attention from health professionals in the past few decades. However, recent studies have shown a high prevalence of insomnia complaints in patients with objectively diagnosed obstructive sleep apnea (OSA) syndrome. In this paper we have reviewed data published on different aspects of this association: the clinical profile of sleep-disordered breathing (SDB)-plus, the nature of the association, the role in the onset of insomnia played by OSA itself and other comorbidity factors such as depression or the restless leg syndrome. Finally, we have reviewed data and hypotheses on the metabolic implications of OSA and insomnia, and we speculate on the role that hypothalamic-pituitary-adrenal axis hyperactivity may play in a hypothetical interrelation between OSA and insomnia. The apparent paradox implied by this clinical association reveals the need for interdisciplinary training for physicians who treat both types of disorders.

The relationship between insomnia and body temperatures

Sleepiness and sleep propensity are strongly influenced by our circadian clock as indicated by many circadian rhythms, most commonly by that of core body temperature. Sleep is most conducive in the temperature minimum phase, but is inhibited in a "wake maintenance zone" before the minimum phase, and is disrupted in a zone following that phase. Different types of insomnia symptoms have been associated with abnormalities of the body temperature rhythm. Sleep onset insomnia is associated with a delayed temperature rhythm presumably, at least partly, because sleep is attempted during a delayed evening wake maintenance zone. Morning bright light has been used to phase advance circadian rhythms and successfully treat sleep onset insomnia. Conversely, early morning awakening insomnia has been associated with a phase advanced temperature rhythm and has been successfully treated with the phase delaying effects of evening bright light. Sleep maintenance insomnia has been associated not with a circadian rhythm timing abnormality, but with nocturnally elevated core body temperature. Combination of sleep onset and maintenance insomnia has been associated with a 24-h elevation of core body temperature supporting the chronic hyper-arousal model of insomnia. The possibility that these last two types of insomnia may be related to impaired thermoregulation, particularly a reduced ability to dissipate body heat from distal skin areas, has not been consistently supported in laboratory studies. Further studies of thermoregulation are needed in the typical home environment in which the insomnia is most evident.