Mood and metabolic consequences of sleep deprivation as a potential endophenotype' in bipolar disorder

Consequences of post-weaning sleep deprivation on behaviour and oxidative stress parameters in rat plasma and brain

Sleep is essential for health: Adequate sleep is essential for healthy development and sleep deprivation results in several consequences. Indeed, sleep deprivation early in life is associated with poor behaviour and cognition, as well as impaired mental and physical health. Preclinical studies have shown that sleep deprivation alters several physiological functions later in life such as the cardiovascular, immune and endocrine systems, resulting in altered oxidative states. Most of the preclinical literature is focused on adult animals, and little is known about oxidative alterations during development, especially in the context of sleep deprivation. Hence, we adapted a classic and well-documented model of sleep deprivation, paradoxical sleep deprivation using multiple platforms, for juvenile rats and explored central and peripheral oxidative parameters, as well as the behavioural consequences of sleep deprivation post-weaning. We showed that 96 h of paradoxical sleep deprivation induced a significant reduction in body weight, decreased sucrose preference-a behaviour suggestive of anhedonia-and increased glucose and decreased cholesterol in the plasma. In the brain, we observed a decrease in reduced glutathione levels in the medial prefrontal cortex and an increase in thiobarbituric acid reactive substance levels in the hypothalamus, indicating oxidative damage in these regions. Taken together, our findings suggest that paradoxical sleep deprivation during development induces anhedonic behaviour and promotes central and peripheral alterations in oxidative parameters.

Evaluation of Nonpharmacologic Interventions and Sleep Outcomes in Hospitalized Medical and Surgical Patients: A Nonrandomized Controlled Trial

IMPORTANCE

Inadequate sleep negatively affects patients' physical health, mental well-being, and recovery. Nonpharmacologic interventions are recommended as first-choice treatment. However, studies evaluating the interventions are often of poor quality and show equivocal results.

OBJECTIVE

To assess whether the implementation of nonpharmacologic interventions is associated with improved inpatient night sleep.

DESIGN, SETTING, AND PARTICIPANTS

In a nonrandomized controlled trial, patients were recruited on the acute medical unit and medical and surgical wards of a Dutch academic hospital. All adults who spent exactly 1 full night in the hospital were recruited between September 1, 2019, and May 31, 2020 (control group), received usual care. Patients recruited between September 1, 2020, and May 31, 2021, served as the intervention group. The intervention group received earplugs, an eye mask, and aromatherapy. Nurses received sleep-hygiene training, and in the acute medical unit, the morning medication and vital sign measurement rounds were postponed from the night shift to the day shift. All interventions were developed in collaboration with patients, nurses, and physicians.

MAIN OUTCOMES AND MEASURES

Sleep was measured using actigraphy and the Dutch-Flemish Patient-Reported Outcomes Measurement Information System sleep disturbance item bank. Other outcomes included patient-reported sleep disturbing factors and the use of sleep-enhancing tools.

RESULTS

A total of 374 patients were included (222 control, 152 intervention; median age, 65 [IQR, 52-74] years). Of these, 331 were included in the analysis (195 [59%] men). Most patients (138 [77%] control, 127 [84%] intervention) were in the acute medical unit. The total sleep time was 40 minutes longer in the intervention group (control: median, 6 hours and 5 minutes [IQR, 4 hours and 55 minutes to 7 hours and 4 minutes]; intervention: 6 hours and 45 minutes [IQR, 5 hours and 47 minutes to 7 hours and 39 minutes]; P < .001). This was mainly due to a 30-minute delay in final wake time (median clock-time: control, 6:30 am [IQR, 6:00 am to 7:22 am]; intervention, 7:00 am [IQR, 6:30-7:30 am]; P < .001). Sleep quality did not differ significantly between groups. For both groups, the main sleep-disturbing factors were noises, pain, toilet visits, and being awakened by hospital staff. Sleep masks (23 of 147 [16%]) and earplugs (17 of 147 [12%]) were used most. Nightly vital sign checks decreased significantly (control: 54%; intervention: 11%; P < .001).

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that sleep of hospitalized patients may be significantly improved with nonpharmacologic interventions. Postponement of morning vital sign checks and medication administration rounds from the night to the day shift may be a useful way to achieve this.

TRIAL REGISTRATION

Netherlands Trial Registry Identifier: NL7995.

Elevated thyroid-stimulating hormone levels are associated with poor sleep: a cross-sectional and longitudinal study

PURPOSE

Poor sleep accompanied by elevated TSH (thyroid stimulating hormone) levels is not uncommon since TSH secretion is controlled by the circadian rhythm. However, the relationship between poor sleep and TSH elevation is unclear; hence, we aimed to elucidate this relationship by conducting a cross-sectional and longitudinal study.

METHODS

Participants with isolated elevated (N = 168) and normal (N = 119) TSH concentrations were recruited, and the Pittsburgh Sleep Quality Index (PSQI) was used to assess the sleep status. Subjects with an isolated TSH elevation were followed up longitudinally. The serum TSH concentration was remeasured after sleep status improved.

RESULTS

The proportions of poor sleep and occasional poor sleep in subjects with isolated TSH elevation were significantly higher than those with normal TSH levels (70.24% vs. 49.58%, p = 0.001; 9.52% vs. 1.68%, p = 0.006). Subjects with isolated TSH elevation had significantly higher PSQI scores in the subjective sleep quality, sleep latency, sleep duration, and habitual sleep efficiency dimensions than those with normal TSH levels (all p < 0.05). Poor sleep was significantly associated with isolated TSH elevation in the multiple logistic regression analysis [odds ratio (OR) = 2.396, p = 0.001]. Among subjects with an isolated TSH elevation at baseline, the percentage of TSH normalization was significantly higher in those who slept better than in those who still slept poorly (85.42% vs. 6.45%, p < 0.001).

CONCLUSIONS

This study revealed that isolated elevated TSH concentrations normalize when the sleep status is improved; hence, we recommend that clinicians thoroughly assess the sleep status of patients and remeasure TSH concentrations after sleep status improves.

The effect of sleep deprivation and restriction on mood, emotion, and emotion regulation: three meta-analyses in one

STUDY OBJECTIVES

New theory and measurement approaches have facilitated nuanced investigation of how sleep loss impacts dimensions of affective functioning. To provide a quantitative summary of this literature, three conceptually related meta-analyses examined the effect of sleep restriction and sleep deprivation on mood, emotion, and emotion regulation across the lifespan (i.e. from early childhood to late adulthood).

METHODS

A total of 241 effect sizes from 64 studies were selected for inclusion, and multilevel meta-analytic techniques were used when applicable.

RESULTS

There was a moderate, positive effect of sleep loss on negative mood (g = 0.45), which was stronger for studies with younger samples, as well as a large, negative effect of sleep loss on positive mood (g = -0.94). For negative mood only, studies that used total sleep deprivation had larger effect sizes than studies that restricted sleep. After correcting for publication bias, a modest but significant negative effect for sleep loss on emotion (g = -0.11) was found; the valence of emotional stimuli did not change the direction of this effect, and type of sleep manipulation was also not a significant moderator. Finally, sleep restriction had a small, negative effect on adaptive emotion regulation (g = -0.32), but no significant impact on maladaptive emotion regulation (g = 0.14); all studies on adaptive emotion regulation were conducted with youth samples.

CONCLUSIONS

Sleep loss compromises optimal affective functioning, though the magnitude of effects varies across components. Findings underscore the importance of sleep for healthy affective outcomes.

Neuroendocrine Stress System in Bipolar Disorder

Hormones have a crucial part in the progress and manifestation of a wide variety of different behaviors. The main influence of the neuroendocrine system on behavior is its action on the neurobiology of neuropsychiatric disorders and its relationship with the pharmacodynamics of medicines. Of all the neuroendocrine axes, the hypothalamic-pituitary-adrenal (HPA) axis has been the most extensively studied. There is evidence that disturbance in the HPA axis, the primary stress hormone system, could increase treatment resistance and relapse, worsen illness outcome, and cause cognitive deficits. Glucocorticoids mediate their actions in negative feedback binding in two different cytoplasmatic receptors described as mineralocorticoid receptors (MRs) and glucocorticoid receptors (GRs). Different psychopathologies underlying bipolar disorders are supposed to involve persistent dysfunctions in the expression and role of both MR and GR in the hippocampus. We review and analyze the evidence related to the correlation between bipolar disorders and the consequences and impact of stressful life events on the HPA axis, exploring the importance of these findings in bipolar disorders and as potential new targets for treatment.

Bipolar affective disorder and borderline personality disorder: Differentiation based on the history of early life stress and psychoneuroendocrine measures

INTRODUCTION

Borderline Personality Disorder (BPD) and Bipolar Affective Disorder (BD) have clinical characteristics in common which often make their differential diagnosis difficult. The history of early life stress (ELS) may be a differentiating factor between BPD and BD, as well as its association with clinical manifestations and specific neuroendocrine responses in each of these diagnoses.

OBJECTIVE

Assessing and comparing patients with BD and BPD for factors related to symptomatology, etiopathogenesis and neuroendocrine markers.

METHODOLOGY

The study sample consisted of 51 women, divided into 3 groups: patients with a clinical diagnosis of BPD (n = 20) and BD (n = 16) and healthy controls (HC, n = 15). Standardized instruments were used for the clinical evaluation, while the history of ELS was quantified with the Childhood Trauma Questionnaire (CTQ), and classified according to the subtypes: emotional abuse, physical abuse, sexual abuse, emotional neglect and physical neglect. The functioning of the hypothalamic-pituitary-adrenal (HPA) axis was evaluated by measuring a single plasma cortisol sample.

RESULTS

Patients with BPD presented with more severe psychiatric symptoms of: anxiety, impulsivity, depression, hopelessness and suicidal ideation than those with BD. The history of ELS was identified as significantly more prevalent and more severe in patients (BPD and BP) than in HC. Emotional abuse, emotional neglect and physical neglect also showed differences and were higher in BPD than BD patients. BPD patients had greater severity of ELS overall and in the subtypes of emotional abuse, emotional neglect and physical neglect than BD patients. The presence of ELS in patients with BPD and BP showed significant difference with lower cortisol levels when compared to HC. The endocrine evaluation showed no significant differences between the diagnoses of BPD and BD. Cortisol measured in patients with BPD was significantly lower compared to HC in the presence of emotional neglect and physical neglect. A significant negative correlation between the severity of hopelessness vs cortisol; and physical neglect vs cortisol were found in BPD with ELS. The single cortisol sample showed a significant and opposite correlations in the sexual abuse diagnosis-related groups, being a negative correlation in BD and positive in BPD.

DISCUSSION

Considering the need for a multi-factorial analysis, the differential diagnosis between BPD and BD can be facilitated by the study of psychiatric symptoms, which are more severe in the BPD patients with a history of early life stress. The function of the HPA axis assessed by this cortisol measure suggests differences between BPD and BP with ELS history.

CONCLUSION

The integrated analysis of psychopathology, ELS and neuroendocrine function may provide useful indicators to differentiate BPD and BD diagnoses. These preliminary data need to be replicated in a more significant sample with improved and multiple assessments of HPA axis activity.

Are You Sleeping? Dyadic Associations of Support, Stress, and Worries Regarding Adult Children on Sleep

Purpose of the study

Sleep is a key factor in maintaining positive health and well-being throughout life. Although the negative outcomes of sleep problems are becoming better understood, less is known about how intergenerational relationships might affect sleep. Thus, this investigation examines the dyadic associations of support for, stress over, and worrying about adult children on sleep quality for husbands and wives.

Design and Methods

The sample included 186 heterosexual married couples drawn from the Family Exchanges Study. To account for nonindependence in the dyadic data and explore questions of mutual influence, we used actor-partner interdependence models.

Results

Husbands' and wives' reports of supporting their adult child and husbands' worry were associated with husbands' sleep quality. Conversely, wives' stress about supporting their adult child was associated with wives' sleep quality. Findings suggest that relationships with adult children have different associations for sleep quality among middle-aged husbands and wives.

Implications

Our findings have implications for health-related research with couples and families and for providers who work with individuals struggling with sleep problems. Assisting aging parents to be aware of and manage ways that stress, support, and concern for adult children relate to their sleep may benefit them in multifaceted ways.

Heterogeneity of sleep quality in relation to circadian preferences and depressive symptomatology among major depressive patients

BACKGROUND

The current study aimed at investigating the latent dimensional structure of sleep quality as indexed by the seven components of the Pittsburgh Sleep Quality Index (PSQI), as well as latent covariance structure between sleep quality, circadian preferences and depressive symptoms.

METHODS

Two hundred twenty-five patients with major depressive disorder (MDD), with an average age of 29.92 ± 10.49 years (aged between 17 and 63), participated in the study. The PSQI, Morningness-Eveningness Questionnaire (MEQ) and Beck Depression Inventory (BDI) were administered to participants. Four sets of latent class analyses were subsequently run to obtain optimal number of latent classes best fit to the data.

RESULTS

Mixture models revealed that sleep quality is multifaceted in MDD. The data best fit to four-latent-class model: Poor Habitual Sleep Quality (PHSQ), Poor Subjective Sleep Quality (PSSQ), Intermediate Sleep Quality (ISQ), and Good Sleep Quality (GSQ). MDD patients classified into GSQ latent class (23.6%) reported the lowest depressive symptoms and were more prone to morningness diurnal preferences compared to other three homogenous sub-groups. Finally, the significant association between eveningness diurnal preferences and depressive symptomatology was significantly mediated by poor sleep quality.

LIMITATION

The cross-sectional nature of the study and the lack of an objective measurement of sleep such as polysomnography recordings was the most striking limitation of the study.

CONCLUSIONS

We concluded sleep quality in relation to circadian preferences and depressive symptoms has a heterogeneous nature in MDD.

The Amygdala, Sleep Debt, Sleep Deprivation, and the Emotion of Anger: A Possible Connection?

The association of sleep with emotions has long been studied. However, not much has been studied about the association of sleep deprivation and sleep debt with the emotion of anger. In this article, we focused on the association of sleep with anger. The results suggest that lack of sleep - sleep deprivation and sleep debt - both lead to the emotion of anger. Some hints about the involvement of the limbic system have been found. Yet, due to a lack of a quantity of evidence, we suggest that more studies are conducted on the same topic to help us have a more in-depth exploration of the association of lack of sleep with anger.

Childhood maltreatment is associated with attachment insecurities, dissociation and alexithymia in bipolar disorder

Child maltreatment is a public health issue that is a well-established risk factor for many psychological conditions, including bipolar disorder. The current study is one of the first to investigate associations among child maltreatment, dissociative symptomatology, alexithymia, anxiety, depression, and attachment insecurities. 40 patients with bipolar disorder-I and 40 healthy subjects matched for age, gender, and education participated in the study. The Dissociative Experiences Scale (DES), Somatoform Dissociation Questionnaire (SDQ), Childhood Trauma Questionnaire (CTQ-28), Toronto Alexithymia Scale (TAS-20), Depression Anxiety Stress Scale (DASS-21), and Experiences in Close Relationships-Revised (ECR-R) were completed by participants. In comparison to control participants, patients with bipolar disorder-I reported significantly more frequent abusive experiences in childhood, higher levels of attachment insecurities, more severe pathological and somatoform dissociation, as well as higher scores on measures of alexithymia, anxiety, depression and psychological stress. Reports of psychopathology among first-degree relatives (OR = 102.169, 95%IC = 4.596-2271.255; P < 0.01) and childhood emotional trauma (OR = 1.032; 95%CI = 0.782-1.363, P = 0.05) significantly contributed to bipolar disorder-I diagnosis. In contrast, absorption was negatively associated with bipolar illness (OR = 0.852; 95% CI = 0.747-0.973, P < 0.05). Our results showed significant associations between childhood trauma exposure and risk of bipolar disorder. Moreover, the results demonstrate that emotional abuse exposure predicts bipolar illness.

Decreased Numbers of Somatostatin-Expressing Neurons in the Amygdala of Subjects With Bipolar Disorder or Schizophrenia: Relationship to Circadian Rhythms

BACKGROUND

Growing evidence points to a key role for somatostatin (SST) in schizophrenia (SZ) and bipolar disorder (BD). In the amygdala, neurons expressing SST play an important role in the regulation of anxiety, which is often comorbid in these disorders. We tested the hypothesis that SST-immunoreactive (IR) neurons are decreased in the amygdala of subjects with SZ and BD. Evidence for circadian SST expression in the amygdala and disrupted circadian rhythms and rhythmic peaks of anxiety in BD suggest a disruption of rhythmic expression of SST in this disorder.

METHODS

Amygdala sections from 12 SZ, 15 BD, and 15 control subjects were processed for immunocytochemistry for SST and neuropeptide Y, a neuropeptide partially coexpressed in SST-IR neurons. Total numbers (Nt) of IR neurons were measured. Time of death was used to test associations with circadian rhythms.

RESULTS

SST-IR neurons were decreased in the lateral amygdala nucleus in BD (Nt, p = .003) and SZ (Nt, p = .02). In normal control subjects, Nt of SST-IR neurons varied according to time of death. This pattern was altered in BD subjects, characterized by decreases of SST-IR neurons selectively in subjects with time of death corresponding to the day (6:00 am to 5:59 pm). Numbers of neuropeptide Y-IR neurons were not affected.

CONCLUSIONS

Decreased SST-IR neurons in the amygdala of patients with SZ and BD, interpreted here as decreased SST expression, may disrupt responses to fear and anxiety regulation in these individuals. In BD, our findings raise the possibility that morning peaks of anxiety depend on a disruption of circadian regulation of SST expression in the amygdala.

Sleep and circadian alterations in people at risk for bipolar disorder: A systematic review

BACKGROUND

Sleep and circadian abnormalities have been mostly demonstrated in bipolar patients. However, it is not clear whether these alterations are present in population at high risk for bipolar disorder (BD), indicating a possible risk factor for this condition.

OBJECTIVE

This systematic review aims to define current evidence about sleep and rhythm alterations in people at risk for BD and to evaluate sleep and circadian disorders as risk factor for BD.

METHODS

The systematic review included all articles about the topic until February 2016. Two researchers performed an electronic search of PubMed and Cochrane Library. Keywords used were 'sleep' or 'rhythm' or 'circadian' AND 'bipolar disorder' or 'mania' or 'bipolar depression' AND 'high-risk' or 'risk'.

RESULTS

Thirty articles were analyzed (7451 participants at risk for BD). Sleep disturbances are frequent in studies using both subjective measures and actigraphy. High-risk individuals reported irregularity of sleep/wake times, poor sleep and circadian rhythm disruption. Poor sleep quality, nighttime awakenings, and inadequate sleep are possible predictive factors for BD. A unique study suggested that irregular rhythms increase risk of conversion. People at risk for BD showed high cortisol levels in different times of day. Studies about anatomopathology, melatonin levels, inflammatory cytokines and oxidative stress were not identified. The most important limitations were differences in sleep and rhythm measures, heterogeneity of study designs, and lack of consistency in the definition of population at risk.

CONCLUSION

Sleep and circadian disturbances are common in people at risk for BD. However, the pathophysiology of these alterations and the impact on BD onset are still unclear.

Family History in Patients with Bipolar Disorder

INTRODUCTION

In this study, we aimed to better understand the genetic transmission of bipolar disorder by examining the family history of patients.

METHODS

Sixty-three patients with bipolar disorder and their families were included. The final sample comprised 156 bipolar patients and their family members. An inclusion criterion was the presence of bipolar disorder history in the family. The diagnosis of other family members was confirmed by analyzing their files, hospital records, and by calling them to the hospital.

RESULTS

Sixty-five patients were women (41.6%) and 91 were men (58.3%) (ratio of men/women: 1.40). When analyzing the results in terms of the transition of disease from the mother's or father's side, similar results were obtained: 25 patients were from the mother's side and 25 patients were from the father's side in 63 cases.

CONCLUSION

The results of our study support the fact that a significant relationship exists between the degree of kinship and the heritability of bipolar disorder and, furthermore, that the effect of the maternal and paternal sides is similar on the transmission of genetic susceptibility.

Delayed sleep phase: An important circadian subtype of sleep disturbance in bipolar disorders

BACKGROUND

Theoretical models of Bipolar Disorder (BD) highlight that sleep disturbances may be a marker of underlying circadian dysregulation. However, few studies of sleep in BD have reported on the most prevalent circadian sleep abnormality, namely Delayed Sleep Phase (DSP).

METHODS

A cross-sectional study of 404 adults with BD who met published clinical criteria for insomnia, hypersomnia or DSP, and who had previously participated in a study of sleep in BD using a comprehensive structured interview assessment.

RESULTS

About 10% of BD cases with a sleep problem met criteria for a DSP profile. The DSP group was younger and had a higher mean Body Mass Index (BMI) than the other groups. Also, DSP cases were significantly more likely to be prescribed mood stabilizers and antidepressant than insomnia cases. An exploratory analysis of selected symptom item ratings indicated that DSP was significantly more likely to be associated with impaired energy and activity levels.

LIMITATIONS

The cross-sectional design precludes examination of longitudinal changes. DSP is identified by sleep profile, not by diagnostic criteria or objective sleep records such as actigraphy. The study uses data from a previous study to identify and examine the DSP group.

CONCLUSIONS

The DSP group identified in this study can be differentiated from hypersomnia and insomnia groups on the basis of clinical and demographic features. The association of DSP with younger age, higher BMI and impaired energy and activity also suggest that this clinical profile may be a good proxy for underlying circadian dysregulation.

The HPA axis in bipolar disorder: Systematic review and meta-analysis

OBJECTIVES

To provide a quantitative and qualitative synthesis of the available evidence on the role of Hypothalamic-Pituitary-Adrenal (HPA) axis in the pathophysiology of Bipolar Disorder (BD).

METHODS

Meta-analysis and meta-regression of case-control studies examining the levels of cortisol, ACTH, CRH levels. Systematic review of stress reactivity, genetic, molecular and neuroimaging studies related to HPA axis activity in BD.

RESULTS

Forty-one studies were included in the meta-analyses. BD was associated with significantly increased levels of cortisol (basal and post-dexamethasone) and ACTH, but not of CRH. In the meta-regression, case-control differences in cortisol levels were positively associated with the manic phase (p=0.005) and participants' age (p=0.08), and negatively with antipsychotics use (p=0.001). Reviewed studies suggest that BD is associated with abnormalities of stress-related molecular pathways in several brain areas. Variants of HPA axis-related genes seem not associated with a direct risk of developing BD, but with different clinical presentations. Also, studies on unaffected relatives suggest that HPA axis dysregulation is not an endophenotype of BD, but seems related to environmental risk factors, such as childhood trauma. Progressive HPA axis dysfunction is a putative mechanism that might underlie the clinical and cognitive deterioration of patients with BD.

CONCLUSIONS

BD is associated with dysfunction of HPA axis activity, with important pathophysiological implications. Targeting HPA axis dysfunctions might be a novel strategy to improve the outcomes of BD.

[Actigraphy in Bipolar Disorder and First Degree Relatives]

BACKGROUND

Bipolar disorder is a disabling disease that involves a significant economic costs to the health system, making it is essential to investigate possible early predictors such as changes in sleep-wake cycle in high-risk populations.

OBJECTIVE

To review the available literature on alterations in the sleep-wake cycle and circadian rhythm in patients with bipolar disorder and their first degree relatives.

METHODS

A literature search was performed in the data bases, Access Medicine, ClinicalKey, EMBASE, JAMA, Lilacs, OVID, Oxford Journals, ScienceDirect, SciELO, APA y PsycNET. Articles in both English and Spanish were reviewed, without limits by study type.

RESULTS

Actigraphy is a non-invasive, useful method for assessing sleep-wake cycle disturbances in the active phases of bipolar disorder, and during euthymia periods. Actigraphy showed good sensitivity to predict true sleep, but low specificity, compared with polysomnography. Although studies in bipolar offspring and relatives are scarce, they show sleep changes similar to bipolar patients.

CONCLUSIONS

Actigraphy may be a good screening tool of sleep/wake cycle in patients with bipolar disorders, because it is economic, non-invasive and sensitive. Longitudinal studies are required to evaluate its potential use as a risk marker.

Circadian rhythm characteristics, poor sleep quality, daytime sleepiness and common psychiatric disorders among Thai college students

INTRODUCTION

To investigate the relationship between common psychiatric disorders (CPDs) and sleep characteristics (evening chronotype, poor sleep quality and daytime sleepiness) among Thai college students.

METHODS

A cross-sectional study was conducted among 2,970 undergraduate students in Thailand. Students were asked to complete a self-administered questionnaire that collected information about lifestyle and demographic characteristics. The Horne and Ostberg Morningness-Eveningness Questionnaire (MEQ), Pittsburgh Sleep Quality Index (PSQI) and Epworth Sleepiness Scale (ESS) were used to evaluate circadian preference, sleep quality and daytime sleepiness, respectively. The General Health Questionnaire-12 (GHQ-12) was used to evaluate presence of CPDs. Logistic regression models were used to estimate adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) of CPDs in relation to the covariates of interest.

RESULTS

A total of 337 students were classified as having CPDs (11.2%; 95% CI 10.1-12.3%). Evening chronotype (OR = 3.35; 95% CI 2.09-5.37), poor sleep quality (OR = 4.89; 95% CI 3.66-6.54) and excessive daytime sleepiness (OR = 1.95; 95% CI 1.54-2.47) were statistically significantly associated with CPDs.

DISCUSSION

Our study demonstrated that CPDs are common among Thai college students. Further, evening chronotype, poor sleep quality and excessive daytime sleepiness were strongly associated with increased risk of CPDs. These findings highlight the importance of educating students and school administrators about the importance of sleep and their impact on mental health.

Investigating the mechanism(s) underlying switching between states in bipolar disorder

Bipolar disorder (BD) is a unique disorder that transcends domains of function since the same patient can exhibit depression or mania, states with polar opposite mood symptoms. During depression, people feel helplessness, reduced energy, and risk aversion, while with mania behaviors include grandiosity, increased energy, less sleep, and risk preference. The neural mechanism(s) underlying each state are gaining clarity, with catecholaminergic disruption seen during mania, and cholinergic dysfunction during depression. The fact that the same patient cycles/switches between these states is the defining characteristic of BD however. Of greater importance therefore, is the mechanism(s) underlying cycling from one state - and its associated neural changes - to another, considered the 'holy grail' of BD research. Herein, we review studies investigating triggers that induce switching to these states. By identifying such triggers, researchers can study neural mechanisms underlying each state and importantly how such mechanistic changes can occur in the same subject. Current animal models of this switch are also discussed, from submissive- and dominant-behaviors to kindling effects. Focus however, is placed on how seasonal changes can induce manic and depressive states in BD sufferers. Importantly, changing photoperiod lengths can induce local switches in neurotransmitter expression in normal animals, from increased catecholaminergic expression during periods of high activity, to increased somatostatin and corticotrophin releasing factor during periods of low activity. Identifying susceptibilities to this switch would enable the development of targeted animal models. From animal models, targeted treatments could be developed and tested that would minimize the likelihood of switching.

Implicit motor learning in bipolar disorder

OBJECTIVES

A growing number of publications describe cerebellar abnormalities in patients with bipolar disorder (BD). The aim of the following paper was to examine the functional aspects of that issue by focusing on implicit learning - a cognitive function with significant cerebellar underpinnings.

METHODS

27 patients with BD and 26 healthy controls (HC), matched for age and sex took part in the study. Implicit motor learning was assessed by the serial reaction time task (SRTT), in which participants were unconsciously learning a sequence of motor reactions. The indicators of procedural learning were the decrease of reaction time (RT) across the repetition of the sequence and the rebound of RT when the sequence changed into a random set of stimuli.

RESULTS

BD patients did not present any indicators of the implicit learning, their RT increased across repetitions of the sequence and it decreased when the sequence changed to random. Contrary, in the control group RT decreased across the sequence repetitions and increased when the stimuli begun to appear randomly.

LIMITATIONS

A low subject count and a non-drug naïve patients group, medicated with atypical antipsychotic and mood stabilizers, are the most significant limitations of this study.

CONCLUSIONS

BD patients did not acquire procedural knowledge while performing the task, whereas HC did. To our knowledge this is the first study that shows the impairment of implicit motor learning in patients with BD. This indicates the possible cerebellar dysfunction in this disease and may provide a new neuropsychiatric approach to bipolar disorder.

Sleep deprivation and gene expression

Sleep occurs in a wide range of animal species as a vital process for the maintenance of homeostasis, metabolic restoration, physiological regulation, and adaptive cognitive functions in the central nervous system. Long-term perturbations induced by the lack of sleep are mostly mediated by changes at the level of transcription and translation. This chapter reviews studies in humans, rodents, and flies to address the various ways by which sleep deprivation affects gene expression in the nervous system, with a focus on genes related to neuronal plasticity, brain function, and cognition. However, the effects of sleep deprivation on gene expression and the functional consequences of sleep loss are clearly not restricted to the cognitive domain but may include increased inflammation, expression of stress-related genes, general impairment of protein translation, metabolic imbalance, and thermal deregulation.

Deepening sleep by hypnotic suggestion

STUDY OBJECTIVES

Slow wave sleep (SWS) plays a critical role in body restoration and promotes brain plasticity; however, it markedly declines across the lifespan. Despite its importance, effective tools to increase SWS are rare. Here we tested whether a hypnotic suggestion to "sleep deeper" extends the amount of SWS.

DESIGN

Within-subject, placebo-controlled crossover design.

SETTING

Sleep laboratory at the University of Zurich, Switzerland.

PARTICIPANTS

Seventy healthy females 23.27 ± 3.17 y.

INTERVENTION

Participants listened to an auditory text with hypnotic suggestions or a control tape before napping for 90 min while high-density electroencephalography was recorded.

MEASUREMENTS AND RESULTS

After participants listened to the hypnotic suggestion to "sleep deeper" subsequent SWS was increased by 81% and time spent awake was reduced by 67% (with the amount of SWS or wake in the control condition set to 100%). Other sleep stages remained unaffected. Additionally, slow wave activity was significantly enhanced after hypnotic suggestions. During the hypnotic tape, parietal theta power increases predicted the hypnosis-induced extension of SWS. Additional experiments confirmed that the beneficial effect of hypnotic suggestions on SWS was specific to the hypnotic suggestion and did not occur in low suggestible participants.

CONCLUSIONS

Our results demonstrate the effectiveness of hypnotic suggestions to specifically increase the amount and duration of slow wave sleep (SWS) in a midday nap using objective measures of sleep in young, healthy, suggestible females. Hypnotic suggestions might be a successful tool with a lower risk of adverse side effects than pharmacological treatments to extend SWS also in clinical and elderly populations.

Daytime sleepiness, poor sleep quality, eveningness chronotype, and common mental disorders among Chilean college students

OBJECTIVES

To evaluate whether daytime sleepiness, poor sleep quality, and morningness and eveningness preferences are associated with common mental disorders (CMDs) among college students.

METHODS

A total of 963 college students completed self-administered questionnaires that collected information about sociodemographic characteristics, sleep quality characteristics, CMDs, and other lifestyle behaviors.

RESULTS

The prevalence of CMDs was 24.3% (95% confidence interval [CI] [21.5%, 27.1%]) among all students. Prevalence estimates of both excessive daytime sleepiness and poor sleep quality were higher among females (35.4% and 54.4%) than males (22.0% and 45.8%). Cigarette smoking was statistically significantly and positively associated with having CMDs (p = .034). Excessive daytime sleepiness (odds ratio [OR] = 3.65; 95% CI [2.56, 4.91]) and poor sleep quality (OR = 4.76; 95% CI [3.11, 7.29]) were associated with increased odds of CMDs.

CONCLUSION

Given the adverse health consequences associated with both sleep disorders and CMDs, improving sleep hygiene among college students is imperative to public health.

Recent advances in sleep-wake cycle and biological rhythms in bipolar disorder

The cyclical nature of periodic switches in energy, motor activation and sleep-wake cycles in bipolar disorder suggests a strong underlying relationship with disturbances in chronobiology. Current research is refining our understanding of the various patterns of sleep-wake and biological rhythms alterations at early and later stages of this illness, as well as across its depressive/fatigue, manic/hypomanic and euthymic phases. This research focuses on early detection and subsequent monitoring to predict and better manage recurrent episodes. Sleep-wake cycle and biological rhythms disturbances are also well known to affect other key aspects of physical health (notably metabolic functions), cognitive performance and elevated risks for suicide. Increasing evidence now supports the integration of behavioural or pharmacological therapeutic strategies that target the sleep-wake and circadian systems in the ongoing treatment of various phases of bipolar disorder.