Insomnia symptoms and biomarkers of monocyte activation, systemic inflammation, and coagulation in HIV: Veterans Aging Cohort Study

Background

Insomnia may be a risk factor for cardiovascular disease in HIV (HIV-CVD); however, mechanisms have yet to be elucidated.

Methods

We examined cross-sectional associations of insomnia symptoms with biological mechanisms of HIV-CVD (immune activation, systemic inflammation, and coagulation) among 1,542 people with HIV from the Veterans Aging Cohort Study (VACS) Biomarker Cohort. Past-month insomnia symptoms were assessed by the item, “Difficulty falling or staying asleep?,” with the following response options: “I do not have this symptom” or “I have this symptom and…” “it doesn’t bother me,” “it bothers me a little,” “it bothers me,” “it bothers me a lot.” Circulating levels of the monocyte activation marker soluble CD14 (sCD14), inflammatory marker interleukin-6 (IL-6), and coagulation marker D-dimer were determined from blood specimens. Demographic- and fully-adjusted (CVD risk factors, potential confounders, HIV-related factors) regression models were constructed, with log-transformed biomarker variables as the outcomes. We present the exponentiated regression coefficient (exp[b]) and its 95% confidence interval (CI).

Results

We observed no significant associations between insomnia symptoms and sCD14 or IL-6. For D-dimer, veterans in the “Bothers a Lot” group had, on average, 17% higher D-dimer than veterans in the “No Difficulty Falling or Staying Asleep” group in the demographic-adjusted model (exp[b] = 1.17, 95%CI = 1.01–1.37, p = .04). This association was nonsignificant in the fully-adjusted model (exp[b] = 1.09, 95%CI = 0.94–1.26, p = .27).

Conclusion

We observed little evidence of relationships between insomnia symptoms and markers of biological mechanisms of HIV-CVD. Other mechanisms may be responsible for the insomnia-CVD relationship in HIV; however, future studies with comprehensive assessments of insomnia symptoms are warranted.

The effect of insomnia on development of Alzheimer's disease

Alzheimer's disease (AD) is the most common type of dementia and a neurodegenerative disorder characterized by memory deficits especially forgetting recent information, recall ability impairment, and loss of time tracking, problem-solving, language, and recognition difficulties. AD is also a globally important health issue but despite all scientific efforts, the treatment of AD is still a challenge. Sleep has important roles in learning and memory consolidation. Studies have shown that sleep deprivation (SD) and insomnia are associated with the pathogenesis of Alzheimer's disease and may have an impact on the symptoms and development. Thus, sleep disorders have decisive effects on AD; this association deserves more attention in research, diagnostics, and treatment, and knowing this relation also can help to prevent AD through screening and proper management of sleep disorders. This study aimed to show the potential role of SD and insomnia in the pathogenesis and progression of AD.

Anxiety and depression in COVID-19 survivors: Role of inflammatory and clinical predictors

Infection-triggered perturbation of the immune system could induce psychopathology, and psychiatric sequelae were observed after previous coronavirus outbreaks. The spreading of the Severe Acute Respiratory Syndrome Coronavirus (COVID-19) pandemic could be associated with psychiatric implications. We investigated the psychopathological impact of COVID-19 in survivors, also considering the effect of clinical and inflammatory predictors. We screened for psychiatric symptoms 402 adults surviving COVID-19 (265 male, mean age 58), at one month follow-up after hospital treatment. A clinical interview and a battery of self-report questionnaires were used to investigate post-traumatic stress disorder (PTSD), depression, anxiety, insomnia, and obsessive-compulsive (OC) symptomatology. We collected sociodemographic information, clinical data, baseline inflammatory markers and follow-up oxygen saturation levels. A significant proportion of patients self-rated in the psychopathological range: 28% for PTSD, 31% for depression, 42% for anxiety, 20% for OC symptoms, and 40% for insomnia. Overall, 56% scored in the pathological range in at least one clinical dimension. Despite significantly lower levels of baseline inflammatory markers, females suffered more for both anxiety and depression. Patients with a positive previous psychiatric diagnosis showed increased scores on most psychopathological measures, with similar baseline inflammation. Baseline systemic immune-inflammation index (SII), which reflects the immune response and systemic inflammation based on peripheral lymphocyte, neutrophil, and platelet counts, positively associated with scores of depression and anxiety at follow-up. PTSD, major depression, and anxiety, are all high-burden non-communicable conditions associated with years of life lived with disability. Considering the alarming impact of COVID-19 infection on mental health, the current insights on inflammation in psychiatry, and the present observation of worse inflammation leading to worse depression, we recommend to assess psychopathology of COVID-19 survivors and to deepen research on inflammatory biomarkers, in order to diagnose and treat emergent psychiatric conditions.

Shuangxia decoction alleviates p-chlorophenylalanine induced insomnia through the modification of serotonergic and immune system

As a Traditional Chinese Medicine (TCM), Shuangxia Decoction (SXD) has been used to treat insomnia in oriental countries for more than thousands of years and it presents remarkable clinical effects. However, its active pharmacological fraction and the mechanism of sedative-hypnotic effects have not been explored. In this paper, we investigated active pharmacological fraction and revealed the detailed mechanisms underlying the sedative-hypnotic effects of SXD. It showed that SXD water extract compared to ethanol extract possessed better sedative effects on locomotion activity in normal mice and increased sleep duration in subhypnotic dose of sodium pentobarbital-treated mice. SXD alleviated p-chlorophenylalanine (PCPA) -induced insomnia by increasing the content of 5-HT in cortex [F (4, 55) = 12.67], decreasing the content of dopamine (DA) and norepinephrine (NE). Furthermore, SXD enhanced the expression of 5-HT_1A and 5-HT_2A receptors in hypothalamic and reduced serum levels of IL-1,TNF-α [F (5, 36) = 15.58]. In conclusion, these results indicated that SXD produced beneficial sedative and hypnotic bioactivities mediated by regulating the serotonergic and immune system.

Systematic genetic analyses of GWAS data reveal an association between the immune system and insomnia

BACKGROUND

Previous studies have inferred a strong genetic component for insomnia. However, the etiology of insomnia is still unclear. The aim of the current study was to explore potential biological pathways, gene networks, and brain regions associated with insomnia.

METHODS

Using pathways (gene sets) from Reactome, we carried out a two-stage gene set enrichment analysis strategy. From a large genome-wide association studies (GWASs) of insomnia symptoms (32,155 cases/26,973 controls), significant gene sets were tested for replication in other large GWASs of insomnia complaints (32,384 cases/80,622 controls). After the network analysis of unique genes within the replicated pathways, a gene set analysis for genes in each cluster/module of the enhancing neuroimaging genetics through meta-analysis GWAS data was performed for the volumes of the intracranial and seven subcortical regions.

RESULTS

A total of 31 of 1,816 Reactome pathways were identified and showed associations with insomnia risk. In addition, seven functionally and topologically interconnected clusters (clusters 0-6) and six gene modules (named Yellow, Blue, Brown, Green, Red, and Turquoise) were associated with insomnia. Moreover, significant associations were detected between common variants of the genes in Cluster 2 with hippocampal volume (p = 0.035; family wise error [FWE] correction) and the red module with intracranial volume (p = 0.047; FWE correction). Functional enrichment for genes in the Cluster 2 and the Red module revealed the involvement of immune responses, nervous system development, NIK/NF-kappaB signaling, and I-kappaB kinase/NF-kappaB signaling. Core genes (UBC, UBB, and UBA52) in the interconnected functional network were found to be involved in regulating brain development.

CONCLUSIONS

The current study demonstrates that the immune system and the hippocampus may play central roles in neurodevelopment and insomnia risk.

Chapter 8 Military Personnel With Traumatic Brain Injuries and Insomnia Have Reductions in PTSD and Improved Perceived Health Following Sleep Restoration: A Relationship Moderated by Inflammation

BACKGROUND

Up to one-third of deployed military personnel sustain a traumatic brain injury (TBI). TBIs and the stress of deployment contribute to the vulnerability for chronic sleep disturbance, resulting in high rates of insomnia diagnoses as well as symptoms of posttraumatic stress disorder (PTSD), depression, and declines in health-related quality of life (HRQOL). Inflammation is associated with insomnia; however, the impact of sleep changes on comorbid symptoms and inflammation in this population is unknown.

METHODS

In this study, we examined the relationship between reported sleep changes and the provision of the standard of care, which could include one or more of the following: cognitive behavioral therapy (CBT), medications, and continuous positive airway pressure (CPAP). We compared the following: (a) the group with a decrease in the Pittsburgh Sleep Quality Index (PSQI; restorative sleep) and (b) the group with no change or increase in PSQI (no change). Independent t tests and chi-square tests were used to compare the groups on demographic and clinical characteristics, and mixed between-within subjects analysis of variance tests were used to determine the effect of group differences on changes in comorbid symptoms. Linear regression models were used to examine the role of inflammation in changes in symptoms and HRQOL.

RESULTS

The sample included 70 recently deployed military personnel with TBI, seeking care for sleep disturbances. Thirty-seven participants reported restorative sleep and 33 reported no sleep changes or worse sleep. The two groups did not differ in demographic characteristics or clinical symptoms at baseline. The TBI+restored sleep group had significant reductions in PTSD and depression over the 3-month period, whereas the TBI+no change group had a slight increase in both PTSD and depression. The TBI+restored sleep group also had significant changes in HRQOL, including the following HRQOL subcomponents: physical functioning, role limitations in physical health, social functioning, emotional well-being, energy/fatigue, and general health perceptions. In a linear regression model using a forced entry method, the dependent variable of change in C-reactive protein (CRP) concentrations was significantly related to changes in PTSD symptoms and HRQOL in the TBI+restored sleep group, with R2=0.43, F33,3=8.31, p<.01.

CONCLUSIONS

Military personnel with TBIs who have a reduction in insomnia symptoms following a standard-of-care treatment report less severe symptoms of depression and PTSD and improved HRQOL, which relate to decreased plasma concentrations of CRP. These findings suggest that treatment for sleep disturbances in this TBI+military population is associated with improvements in health and decreases in inflammation. The contributions of inflammation-induced changes in PTSD and depression in sleep disturbances in TBI + military personnel require further study.

Exercise improves immune function, antidepressive response, and sleep quality in patients with chronic primary insomnia

The aim of this study was to evaluate the effects of moderate aerobic exercise training on sleep, depression, cortisol, and markers of immune function in patients with chronic primary insomnia. Twenty-one sedentary participants (16 women aged 44.7 ± 9 years) with chronic primary insomnia completed a 4-month intervention of moderate aerobic exercise. Compared with baseline, polysomnographic data showed improvements following exercise training. Also observed were reductions in depression symptoms and plasma cortisol. Immunologic assays revealed a significant increase in plasma apolipoprotein A (140.9 ± 22 to 151.2 ± 22 mg/dL) and decreases in CD4 (915.6 ± 361 to 789.6 ± 310 mm(3)) and CD8 (532.4 ± 259 to 435.7 ± 204 mm(3)). Decreases in cortisol were significantly correlated with increases in total sleep time (r = -0.51) and REM sleep (r = -0.52). In summary, long-term moderate aerobic exercise training improved sleep, reduced depression and cortisol, and promoted significant changes in immunologic variables.

Cross-translational studies in human and Drosophila identify markers of sleep loss

Inadequate sleep has become endemic, which imposes a substantial burden for public health and safety. At present, there are no objective tests to determine if an individual has gone without sleep for an extended period of time. Here we describe a novel approach that takes advantage of the evolutionary conservation of sleep to identify markers of sleep loss. To begin, we demonstrate that IL-6 is increased in rats following chronic total sleep deprivation and in humans following 30 h of waking. Discovery experiments were then conducted on saliva taken from sleep-deprived human subjects to identify candidate markers. Given the relationship between sleep and immunity, we used Human Inflammation Low Density Arrays to screen saliva for novel markers of sleep deprivation. Integrin αM (ITGAM) and Anaxin A3 (AnxA3) were significantly elevated following 30 h of sleep loss. To confirm these results, we used QPCR to evaluate ITGAM and AnxA3 in independent samples collected after 24 h of waking; both transcripts were increased. The behavior of these markers was then evaluated further using the power of Drosophila genetics as a cost-effective means to determine whether the marker is associated with vulnerability to sleep loss or other confounding factors (e.g., stress). Transcript profiling in flies indicated that the Drosophila homologues of ITGAM were not predictive of sleep loss. Thus, we examined transcript levels of additional members of the integrin family in flies. Only transcript levels of scab, the Drosophila homologue of Integrin α5 (ITGA5), were associated with vulnerability to extended waking. Since ITGA5 was not included on the Low Density Array, we returned to human samples and found that ITGA5 transcript levels were increased following sleep deprivation. These cross-translational data indicate that fly and human discovery experiments are mutually reinforcing and can be used interchangeably to identify candidate biomarkers of sleep loss.

A pilot study evaluating the clinical and immunomodulatory effects of an orally administered extract of Dendrobium huoshanense in children with moderate to severe recalcitrant atopic dermatitis

Atopic dermatitis (AD) is a common inflammatory skin disorder for which few safe and effective systemic treatments are available. To test the clinical and immunomodulatory effects of a crude polysaccharide fraction isolated from Dendrobium huoshanense for the treatment of AD, we conducted a pilot, uncontrolled case series study. Twenty-seven patients aged 4-18 years (mean∓SD, 10.82±4.4) with AD that had not responded to topical therapy were treated with polysaccharide derived from D. huoshanense for 4 weeks and followed-up for another 4 weeks. Progression of AD was determined with the Lund-Browder chart for children, the Investigator's Global Atopic Dermatitis Assessment (IGADA), and the Scoring Atopic Dermatitis (SCORAD) at weeks 0, 2, 4, and 8. Serum levels of cytokines were evaluated. Safety was determined with laboratory and clinical tests. The lesion area, IGADA score, total SCORAD result, and score for sleeplessness decreased significantly from weeks 0 to 4, but did not change significantly between weeks 4 and 8. The scores for subjective symptoms and pruritus decreased significantly from week 0 to week 4 and increased significantly from week 4 to week 8. Serum levels of IL-5, IL-13, IFN-gamma, and TGF-beta1 decreased significantly between weeks 0 and 4 and between weeks 0 and 8. No significant difference in the levels of IL-10 was found. The polysaccharide from D. huoshanense reduced the levels of some cytokines associated with AD and had beneficial effects on symptoms. No serious adverse effects occurred when it was administered orally for 4 weeks.

A human anti-neuronal autoantibody against GABAB receptor induces experimental autoimmune agrypnia

In the serum and cerebrospinal fluid of a patient with recurrent acute episodes of respiratory crises, autonomic symptoms and total insomnia (agrypnia), we identified a novel anti-neural complement fixing antibody directed against GABA(B) receptor (GABA(B)R). Patient purified IgG recognized a band of approximately 110 kDa on protein extracts of mouse cerebellum, cortex and brainstem and immunolabelled cultured Chinese hamster ovary (CHO) cells, transfected with human GABA(B)R1 and rat GABA(B)R2 receptors. Western blot analysis of transfected CHO homogenates showed the same band using both patient purified IgG and anti-GABA(B)R1 antibody. In order to verify the pathogenic role of these purified antibodies, we injected patient IgG intrathecally into cisterna magna of C57BL/6 mice pre-implanted with EEG electrodes and we observed severe ataxia followed by breathing depression and total suppression of slow wave sleep, as evidenced by EEG recording, in a dose-dependent manner. Immunohistochemistry on brain sections of mice injected with patient IgG showed the simultaneous presence of bound human IgG and C5b-9 deposits on Purkinje cells and cerebellar granular layer. After incubation with anti-GABA(B)R antibody, a marked reduction of receptor immunostaining was found with relative sparing of neuronal architecture. In conclusion we recognized an anti-neuronal autoantibody directed against GABA(B)R that is associated with autoimmune agrypnia and we showed that our patient purified IgG was able to induce in mice experimental autoimmune agrypnia characterized by a complex neurological syndrome affecting several CNS functions.

Increased nocturnal interleukin-6 excretion in patients with primary insomnia: a pilot study

The aim of the present study was to investigate whether there is a difference in evening/nocturnal interleukin-6 (IL-6) serum excretion in patients with primary insomnia compared to controls. We hypothesized that in insomniac patients, the excretion of evening/nocturnal IL-6 is enhanced, like observed in aged adults and after sleep deprivation in healthy subjects. We studied IL-6 serum concentrations in 11 patients (two males and nine females) with primary insomnia and 11 age and gender-matched healthy controls. Sleep was monitored polysomnographically for three consecutive nights. The measurement of IL-6 (from 19:00 h to 09:00 h) in 2-h intervals were performed prior to and during the last laboratory night. Polysomnographically determined sleep parameters and subjective ratings of sleep demonstrated clear-cut impairments of sleep in the insomniac group. Nocturnal IL-6 secretion was significantly increased (p<.05) in insomniac patients for the whole measurement period (mean area under the curve+/-SD: 27.94+/-14.15 pg/ml x 2h) compared to controls (16.70+/-7.64 pg/ml x 2h). Total IL-6 secretion correlated inversely with subjectively perceived sleep quality and amount of slow wave sleep in the insomniac patients. Amount of Wake Time correlated positively with IL-6 excretion in insomniacs. The results of the present study demonstrate significantly increased nocturnal IL-6 secretion in insomniacs. It might be speculated that chronic primary insomnia with polysomnographically documented sleep impairments activates the production of IL-6 analogous to sleep deprivation studies in healthy subjects. This might also implicate a higher risk for inflammatory and cardiovascular diseases in patients with chronic insomnia.

Randomized study on the efficacy of cognitive-behavioral therapy for insomnia secondary to breast cancer, part II: Immunologic effects

PURPOSE

Cross-sectional studies suggest that clinical insomnia is associated with immune downregulation. However, there is a definite need for experimental studies on this question. The goal of this randomized controlled study was to assess the effect of an 8-week cognitive-behavioral therapy (CBT) for chronic insomnia on immune functioning of breast cancer survivors. Previous analyses of this study showed that CBT was associated with improved sleep and quality of life, and reduced psychological distress.

PATIENTS AND METHODS

Fifty-seven women with chronic insomnia secondary to breast cancer were randomly assigned to CBT (n = 27) or to a waiting-list control condition (WLC; n = 30). Peripheral-blood samples were taken at baseline and post-treatment (and postwaiting for WLC patients), as well as at 3-, 6-, and 12-month follow-up for immune measures, including enumeration of blood cell counts (ie, WBCs, monocytes, lymphocytes, CD3+, CD4+, CD8+, and CD16+/CD56+) and cytokine production (ie, interleukin-1-beta [IL-1beta] and interferon gamma [IFN-gamma]).

RESULTS

Patients treated with CBT had higher secretion of IFN-gamma and lower increase of lymphocytes at post-treatment compared with control patients. Pooled data from both treated groups indicated significantly increased levels of IFN-gamma and IL-1beta from pre- to post-treatment. In addition, significant changes in WBCs, lymphocytes, and IFN-gamma were found at follow-up compared with post-treatment.

CONCLUSION

This study provides some support to the hypothesis of a causal relationship between clinical insomnia and immune functioning. Future studies are needed to investigate the clinical impact of such immune alterations.

Coemergence of insomnia and a shift in the Th1/Th2 balance toward Th2 dominance

OBJECTIVES

Insomnia is associated with physical and mental disorders. We examined the effect of insomnia on immune functions, focusing on the T helper 1 (Th1)/ T helper 2 (Th2) balance, by a cross-sectional design.

METHODS

We provided a self-administered questionnaire to evaluate sleep habits, smoking and medical disorders to 578 men without any toxic exposure (20-64 years old), and measured natural killer (NK) cell activity in 324 men and production of interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) after stimulation with phytohemagglutinin in 254 men. According to the criteria of DSM-IV, in which insomnia is classified into primary and secondary insomnia, we assessed the effect of insomnia on immune functions, controlling for age and smoking in groups with and without medical disorders.

RESULTS

The prevalence of insomnia in the present study was 9.2%. In the absence of medical disorders, insomniac men had a significantly lower IFN-gamma and ratio of IFN-gamma to IL-4 than noninsomniac men. Men with insufficient sleep or difficulty initiating sleep (DIS) had a significantly lower IFN-gamma to IL-4 ratio than those not suffering from insufficient sleep or DIS. In the presence of medical disorders, insomniac men had significantly higher IL-4 than noninsomniac men. Men with difficulty maintaining sleep (DMS) had a significantly lower IFN-gamma to IL-4 ratio than men without DMS. NK cell activity was independent of insomnia.

CONCLUSIONS

The present results showed a link between insomnia unrelated to medical disorders and a shift in the Th1/Th2 balance toward Th2 dominance, indicating that the relationship between sleep quality and the etiology of immune-related diseases should be reconsidered.

Nocturnal catecholamines and immune function in insomniacs, depressed patients, and control subjects

Insomnia predicts cardiovascular and non-cardiovascular disease mortality. This study evaluated EEG sleep, nocturnal sympathetic activity, and daytime measures of immune function in subjects with primary insomnia (n = 17) and patients with current major depression (n = 14) as compared to controls (n = 31). Insomniacs showed disordered sleep continuity along with nocturnal increases of average levels of circulating norepinephrine and decreases of natural killer cell responses, whereas depressed patients showed declines of natural killer cell activity, but no differences of EEG sleep or nocturnal catecholamines as compared to controls. Impairments of sleep efficiency correlated with nocturnal elevations of norepinephrine in the insomniacs but not in the depressives or controls. These data indicate that insomnia is associated with nocturnal sympathetic arousal and declines of natural immunity, and further support the role of sleep in the regulation of sympathetic nervous and immune system functioning.

Chronic insomnia and immune functioning

OBJECTIVE

The goal of this study was to investigate whether clinical insomnia is associated with immune alterations by comparing immune functioning between patients with chronic insomnia and good sleepers.

METHODS

The good sleepers group was composed of 19 adults with a regular sleep schedule and no complaint of sleep disturbances. The insomnia group was composed of 17 adults meeting criteria for a chronic primary insomnia disorder. Peripheral blood samples were taken at the interview (time 1) and before the second night of polysomnographic assessment (time 2) for immune measures, including enumeration of blood cell counts (ie, white blood cells, monocytes, lymphocytes, and CD3+, CD4+, CD8+, and CD16+/CD56+ cells), natural killer cell activity, and cytokine production (ie, interleukin-1beta, interleukin-2, and interferon gamma).

RESULTS

Significant between-group differences were observed for CD3+, CD4+, and CD8+ cells, with higher levels found in good sleepers. In addition, a significant group-by-time interaction was found on monocyte counts. Although this was the only significant interaction effect observed, between-group differences were greater at time 2.

CONCLUSIONS

This study suggests that chronic insomnia is associated with some immune alterations. More research is needed to determine the clinical significance of these findings.

Effects of sleep and sleep loss on immunity and cytokines

Sleep is hypothesized to be a restorative process that is important for the proper functioning of the immune system. Severity of disordered sleep in depressed- and alcoholic subjects correlates with declines in natural- and cellular immunity and is associated with alterations in the complex cytokine network. Sleep loss has a role in mediating these immune changes as experimentally induced partial night sleep deprivation replicates the kind of sleep loss found in clinical samples and induces a pattern of immune alterations similar to that found in depressed- and alcoholic patients. Despite evidence that sleep and sleep loss have effects on immune processes and nocturnal secretion of cytokines, the clinical significance of these immune changes is not known. Moreover, in view of basic evidence of a reciprocal interaction between sleep and cytokines, further research is needed to understand whether alterations in cytokines contribute to disordered sleep in patient populations.

Psychoneuroimmunology: new avenues of research for the twenty-first century

Psychoneuroimmunology (PNI) investigates the relations between the psychophysiological and immunophysiological dimensions of living beings. PNI brings together researchers in a number of scientific and medical disciplines, including psychology, the neurosciences, immunology, physiology, pharmacology, psychiatry, behavioral medicine, infectious diseases, and rheumatology. All are scientists with profound interest in interactions between the nervous and immune systems, and the relation between behavior and health. Despite the variety in domains and approaches to research, the outcome common to all research endeavors is the discovery of new information, of uncovered facts, of novel evidence, which contributes to the continuing generation of knowledge. In this paper we discuss psychoneuroimmune aspects of some conditions that are not routinely immediately associated with immunity, such as the condition of being the caregiver of somebody suffering from dementia; the effect on the brain-body modulations of aluminum, a metal that is not a component of the human body; and insomnia, a fairly common but disturbing disease, that even today lacks an effectual treatment.

Experimental immunomodulation, sleep, and sleepiness in humans

Infection, inflammation, and autoimmune processes are accompanied by serious disturbances of well-being, psychosocial functioning, cognitive performance, and behavior. Here we review those studies that have investigated the effects of experimental immunomodulation on sleep and sleepiness in humans. In most of these studies bacterial endotoxin was injected intravenously to model numerous aspects of infection including the release of inflammatory cytokines. These studies show that human sleep-wake behavior is very sensitive to host defense activation. Small amounts of endotoxin, which affect neither body temperature nor neuroendocrine systems but slightly stimulate the secretion of inflammatory cytokines, promote non-rapid-eye-movement sleep amount and intensity. Febrile host responses, in contrast, go along with prominent sleep disturbances. According to present knowledge tumor necrosis factor-alpha (TNF-alpha) is most probably a key mediator of these effects, although it is likely that disturbed sleep during febrile host responses involves endocrine systems as well. There is preliminary evidence from human studies suggesting that inflammatory cytokines such as TNF-alpha not only mediate altered sleep-wake behavior during infections, but in addition are involved in physiological sleep regulation and in hypnotic effects of established sedating drugs.

Immunity and depression: insomnia, retardation, and reduction of natural killer cell activity

Depressed patients show a reduction of natural killer (NK) cell activity which may be associated with specific depressive symptoms. The present study demonstrated that sleep disturbance and retardation, but not other depressive symptoms, were negatively correlated with NK activity in 38 depressed patients. Specific behavioral changes in depression such as sleep disturbance and retardation were found to predict 16% of the variance of cytotoxicity levels in depression.

Psychomotor retardation, anorexia, weight loss, sleep disturbances, and loss of energy: psychopathological correlates of hyperhaptoglobinemia during major depression

Recently, we have established that major depression is characterized by hyperhaptoglobinemia, which may be regarded as an index of an "acute" phase response in that illness. The present study investigates the psychopathological correlates of increased plasma concentrations of haptoglobin (Hp) in major depression. To this end, the authors studied the Hp levels in relation to depressive items of the Structured Clinical Interview for DSM-III (SCID) and the Hamilton Rating Scale for Depression (HRSD) in 90 depressed subjects. There was a significant positive relationship between the SCID symptoms anorexia/weight loss, sleep, and psychomotor disorders and Hp plasma concentrations. Hp plasma levels were significantly and positively correlated with overall severity of illness (HRSD). The HRSD symptom correlates of higher Hp levels were loss of interest, middle insomnia, and psychomotor retardation. Up to 31.4% of the variance in Hp plasma values could be explained by psychomotor disorders, anorexia, weight loss, middle insomnia, and less diurnal variation of mood. It is suggested that hyperhaptoglobinemia, as an index of an "acute" phase response in major depression, is related to the somatic dimension of depressive illness.