Chronobiology, excessive daytime sleepiness and depression: Is there a link?

A genome-wide association study identifies candidate genes for sleep disturbances in depressed individuals

OBJECTIVE

This study aimed to identify candidate loci and genes related to sleep disturbances in depressed individuals and clarify the co-occurrence of sleep disturbances and depression from the genetic perspective.

METHODS

The study subjects (including 58,256 self-reported depressed individuals and 6,576 participants with PHQ-9 score ≥ 10, respectively) were collected from the UK Biobank, which were determined based on the Patient Health Questionnaire (PHQ-9) and self-reported depression status, respectively. Sleep related traits included chronotype, insomnia, snoring and daytime dozing. Genome-wide association studies (GWASs) of sleep related traits in depressed individuals were conducted by PLINK 2.0 adjusting age, sex, Townsend deprivation index and 10 principal components as covariates. The CAUSALdb database was used to explore the mental traits associated with the candidate genes identified by the GWAS.

RESULTS

GWAS detected 15 loci significantly associated with chronotype in the subjects with self-reported depression, such as rs12736689 at RNASEL (P = 1.00 × 10- 09), rs509476 at RGS16 (P = 1.58 × 10- 09) and rs1006751 at RFX4 (P = 1.54 × 10- 08). 9 candidate loci were identified in the subjects with PHQ-9 ≥ 10, of which 2 loci were associated with insomnia such as rs115379847 at EVC2 (P = 3.50 × 10- 08), and 7 loci were associated with daytime dozing, such as rs140876133 at SMYD3 (P = 3.88 × 10- 08) and rs139156969 at ROBO2 (P = 3.58 × 10- 08). Multiple identified genes, such as RNASEL, RGS16, RFX4 and ROBO2 were reported to be associated with chronotype, depression or cognition in previous studies.

CONCLUSION

Our study identified several candidate genes related to sleep disturbances in depressed individuals, which provided new clues for understanding the biological mechanism underlying the co-occurrence of depression and sleep disorders.

Effects of co-sleeping with a shift worker on sleep, mood and cognition

Objective

Although the negative effects of shift work on workers' sleep and mood are well-known, the effects of shift work on their sleep partners' sleep and mood have rarely been investigated. The current study explored the effects of co-sleeping with a shift worker (SW) on the partner's subjective sleep quality, daytime sleepiness, depressive symptoms, and cognitive disturbances.

Methods

Online sleep and work-environment self-report questionnaires (e.g., including the presence of co-sleepers, work schedules of the co-sleepers, and their work schedules) were administered. The questionnaires also included the Pittsburgh Sleep Quality Index (PSQI), the Epworth Sleepiness Scale (ESS), the Cognitive Failures Questionnaire (CFQ), and the short-term Center for Epidemiologic Studies-Depression scale (CES-D). Participants consisted of co-sleepers of SWs (n = 657), co-sleepers of non-SWs (n = 2186), and solo sleepers (n = 2432).

Results

Significant between-group differences in the PSQI, ESS, CFQ, and CES-D were observed after controlling for age, gender, work shift, and parenting (p < 0.001). Co-sleepers of SWs showed higher PSQI, ESS, CFQ, and CES-D scores than co-sleepers of non-SWs and solo sleepers. Solo sleepers reported significantly higher PSQI and CES-D scores than co-sleepers of non-SWs. The PSQI, ESS, CFQ, and CES-D scores were significantly correlated in all groups. The association between the ESS and PSQI was stronger in co-sleepers of SWs than in solo sleepers. The association between the ESS and CES-D was stronger in co-sleepers of SWs than in solo sleepers.

Conclusions

Co-sleeping with SWs is associated with poor sleep quality, daytime sleepiness, depressive symptoms, and cognitive disturbances in the partner.

Circadian misalignment alters resting-state functional connectivity of the salience network in rotating shift workers

STUDY OBJECTIVES

This study compared resting-state functional connectivity (rsFC) of the salience network (SN) between rotating shift workers (RSWs) and controls. Furthermore, we examined whether rsFC of the SN was correlated with sleep, emotion, cognition, and attention.

METHODS

The 60 RSWs and 57 controls enrolled in this study completed self-report questionnaires and sleep diaries to assess subjective sleep quality, and polysomnography and actigraphy to evaluate objective sleep and 24-hour rest-activity rhythm parameters. The participants also underwent resting-state functional magnetic resonance imaging and structural T1 scans. We performed a seed-based rsFC analysis of the SN using the anterior cingulate cortex (ACC) and anterior insula (AI) as seed regions. Furthermore, AI and ACC rsFC were compared in RSWs and controls, and we analyzed correlations between rsFC and variables of interest showing significant group differences.

RESULTS

Compared with controls, RSWs showed reduced rsFC between the ACC and right insula, and increased rsFC of the ACC with the left occipital lobe and right superior frontal gyrus extending to the supplementary motor area (SFG/SMA). Moreover, RSWs showed reduced rsFC between the right AI and right superior parietal lobule (SPL). Finally, rsFC between the ACC and right AI was correlated with 24-hour rest-activity rhythmicity.

CONCLUSIONS

Although RSWs did not show sleep disturbance, emotional distress, cognitive impairment, or attention deficits, alterations of right insula, left occipital lobe, right SFG/SMA, and right SPL rsFC in the SN indicate that impairments in salience detection and top-down attentional control may emerge in shift workers over time.

Depression and bipolar disorder subtypes differ in their genetic correlations with biological rhythms

Major Depression and Bipolar Disorder Type I (BIP-I) and Type II (BIP-II), are characterized by depressed, manic, and hypomanic episodes in which specific changes of physical activity, circadian rhythm, and sleep are observed. It is known that genetic factors contribute to variation in mood disorders and biological rhythms, but unclear to what extent there is an overlap between their underlying genetics. In the present study, data from genome-wide association studies were used to examine the genetic relationship between mood disorders and biological rhythms. We tested the genetic correlation of depression, BIP-I, and BIP-II with physical activity (overall physical activity, moderate activity, sedentary behaviour), circadian rhythm (relative amplitude), and sleep features (sleep duration, daytime sleepiness). Genetic correlations of depression, BIP-I, and BIP-II with biological rhythms were compared to discover commonalities and differences. A gene-based analysis tested for associations of single genes and common circadian genes with mood disorders. Depression was negatively correlated with overall physical activity and positively with sedentary behaviour, while BIP-I showed associations in the opposite direction. Depression and BIP-II had negative correlations with relative amplitude. All mood disorders were positively correlated with daytime sleepiness. Overall, we observed both genetic commonalities and differences across mood disorders in their relationships with biological rhythms: depression and BIP-I differed the most, while BIP-II was in an intermediate position. Gene-based analysis suggested potential targets for further investigation. The present results suggest shared genetic underpinnings for the clinically observed associations between mood disorders and biological rhythms. Research considering possible joint mechanisms may offer avenues for improving disease detection and treatment.

Assessing the depression risk in the U.S. adults using nomogram

BACKGROUND

Depression has received a lot of attention as a common and serious illness. However, people are rarely aware of their current depression risk probabilities. We aimed to develop and validate a predictive model applicable to the risk of depression in US adults.

METHODS

This study was conducted using the database of the National Health and Nutrition Examination Survey (NHANES, 2017-2012). In particular, NHANES (2007-2010) was used as the training cohort (n = 6015) for prediction model construction and NHANES (2011-2012) was used as the validation cohort (n = 2812) to test the model. Depression was assessed (defined as a binary variable) by the Patient Health Questionnaire (PHQ-9). Socio-demographic characteristics, sleep time, illicit drug use and anxious days were assessed using a self-report questionnaire. Logistic regression analysis was used to evaluate independent risk factors for depression. The nomogram has the advantage of being able to visualize complex statistical prediction models as risk estimates of individualized disease probabilities. Then, we developed two depression risk nomograms based on the results of logistic regression. Finally, several validation methods were used to evaluate the prediction performance of nomograms.

RESULTS

The predictors of model 1 included gender, age, income, education, marital status, sleep time and illicit drug use, and model 2, furthermore, included anxious days. Both model 1 and model 2 showed good discrimination ability, with a bootstrap-corrected C index of 0.71 (95% CI, 0.69-0.73) and 0.85 (95% CI, 0.83-0.86), and an externally validated C index of 0.71 (95% CI, 0.68-0.74) and 0.83 (95% CI, 0.81-0.86), respectively, and had well-fitted calibration curves. The area under the receiver operating characteristic curve (AUC) values of the models with 1000 different weighted random sampling and depression scores of 10-17 threshold range were higher than 0.7 and 0.8, respectively. Calculated net reclassification improvement (NRI) and integrated discrimination improvement (IDI) showed the discrimination or accuracy of the prediction models. Decision curve analysis (DCA) demonstrated that the depression models were practically useful. The network calculators work for participants to make personalized predictions.

CONCLUSIONS

This study presents two prediction models of depression, which can effectively and accurately predict the probability of depression as well as helping the U.S. civilian non-institutionalized population to make optimal treatment decisions.

Multi-Level Processes and Retina-Brain Pathways of Photic Regulation of Mood

Light exerts powerful biological effects on mood regulation. Whereas the source of photic information affecting mood is well established at least via intrinsically photosensitive retinal ganglion cells (ipRGCs) secreting the melanopsin photopigment, the precise circuits that mediate the impact of light on depressive behaviors are not well understood. This review proposes two distinct retina–brain pathways of light effects on mood: (i) a suprachiasmatic nucleus (SCN)-dependent pathway with light effect on mood via the synchronization of biological rhythms, and (ii) a SCN-independent pathway with light effects on mood through modulation of the homeostatic process of sleep, alertness and emotion regulation: (1) light directly inhibits brain areas promoting sleep such as the ventrolateral preoptic nucleus (VLPO), and activates numerous brain areas involved in alertness such as, monoaminergic areas, thalamic regions and hypothalamic regions including orexin areas; (2) moreover, light seems to modulate mood through orexin-, serotonin- and dopamine-dependent pathways; (3) in addition, light activates brain emotional processing areas including the amygdala, the nucleus accumbens, the perihabenular nucleus, the left hippocampus and pathways such as the retina–ventral lateral geniculate nucleus and intergeniculate leaflet–lateral habenula pathway. This work synthetizes new insights into the neural basis required for light influence mood

Association between napping status and depressive symptoms in urban residents during the COVID-19 epidemic

: To explore the association between napping status and depressive symptoms in urban residents during the coronavirus disease 2019 (COVID-19) epidemic. : The survey was embedded in the Wellness Living Laboratory-China (WELL China) cohort study. Health and lifestyle information during the COVID-19 epidemic were obtained via the telephone interview from April 8, 2020 to May 29, 2020. A total of 3075 residents aged 18 to from Gongshu district of Hangzhou city with complete data were included in the analyses. The World Health Organization-Five Well-being Index (WHO-5) was used to measure depressive symptoms. Multiple logistic regression model was used to assess the association between napping status and depressive symptoms in the participants. : The prevalence of depressive symptoms was 20.6% in the participants during the epidemic. Daytime napping behavior, especially napping time ≤30 min, was associated with a lower risk of prevalent depressive symptoms (=0.61, 95%: 0.47-0.79, <0.01) and incident depressive symptoms in the population (=0.66, 95%: 0.50-0.88, <0.01). Among those with depressive symptoms at baseline, napping time ≤ was beneficial for the outcome of depressive symptoms (=0.42, 95%: 0.21-0.82, <0.05). : One in five urban residents have depressive symptoms during the COVID-19 epidemic, and a short nap during the day may be a protective factor against depressive symptoms.

Fatigue is associated with depression independent of excessive daytime sleepiness in the general population

PURPOSE

This study aimed to investigate sleep problems and comorbid conditions associated with fatigue in the general population.

METHODS

The data were obtained from a nationwide cross-sectional survey conducted in 2018. The Fatigue Severity Scale was used to assess fatigue. We examined sleep habits, such as workday sleep duration, chronotype, and free-day catch-up sleep, excessive daytime sleepiness (EDS), depression, and other comorbid conditions. We conducted multiple logistic regression analysis with the presence of fatigue as a dependent variable.

RESULTS

Of 2,493 adults aged 19 to 92 years, 50% men, mean age was 47.9 ± 16.4 years. The average workday sleep duration was 7.1 ± 1.1 h, and the prevalence of fatigue was 31%. After adjusting for potential confounders, fatigue was associated with EDS (odds ratio [OR] 3.751, 95% confidence interval [CI] 2.928-4.805), depression (OR 3.736, 95% CI 2.701-5.169), perceived insufficient sleep (OR 1.516, 95% CI 1.249-1.839), free-day catch-up sleep (OR 1.123, 95% CI 1.020-1.235), less alcohol intake (OR 0.570, 95% CI 0.432-0.752), and physical inactivity (OR 0.737, 95% CI 0.573-0.948). On subgroup analysis, fatigue was additionally associated with short workday sleep duration (OR 0.899, 95% CI 0.810-0.997) in individuals without EDS. However, among those with EDS, only depression (OR 2.842, 95% CI 1.511-5.343) and less alcohol intake (OR 0.476, 95% CI 0.247-0.915) were associated with fatigue.

CONCLUSION

Fatigue was significantly associated with depression independent of EDS. Further research is warranted to better understand the pathophysiological relationship between fatigue, depression, and sleep.

Sleepiness as motivation: a potential mechanism for how sleep deprivation affects behavior

STUDY OBJECTIVES

To determine how sleepiness and sleep deprivation drive the motivation to engage in different behaviors.

METHODS

We studied the sleepiness of 123 participants who had been randomized to sleep deprivation or normal sleep, and their willingness to engage in a range of everyday behaviors.

RESULTS

Self-reported sleepiness was a strong predictor of the motivation to engage in sleep-preparatory behaviors such as shutting one's eyes (OR = 2.78, 95% CI: 2.19-3.52 for each step up on the Karolinska Sleepiness Scale) and resting (OR = 3.20, CI: 2.46-4.16). Sleepiness was also related to the desire to be cared for by a loved one (OR = 1.49, CI: 1.22-1.82), and preparedness to utilize monetary and energy resources to get to sleep. Conversely, increased sleepiness was associated with a decreased motivation for social and physical activities (e.g. be with friends OR = 0.71, CI: 0.61-0.82; exercise OR = 0.65, CI: 0.56-0.76). Sleep deprivation had similar effects as sleepiness on these behaviors. Neither sleepiness nor sleep deprivation had strong associations with hunger, thirst, or food preferences.

CONCLUSIONS

Our findings indicate that sleepiness is a dynamic motivational drive that promotes sleep-preparatory behaviors and competes with other drives and desired outcomes. Consequently, sleepiness may be a central mechanism by which impaired alertness, for example, due to insufficient sleep, contributes to poor quality of life and adverse health. We propose that sleepiness helps organize behaviors toward the specific goal of assuring sufficient sleep, in competition with other needs and incentives. A theoretical framework on sleepiness and its behavioral consequences are likely to improve our understanding of several disease mechanisms.

Chronobiology and Chronotherapy in Depression: Current Knowledge and Chronotherapeutic Promises

Background:

Depression is a heavily prevalent mental disorder. Symptoms of depression extend beyond mood, cognition, and behavior to include a spectrum of somatic manifestations in all organic systems. Changes in sleep and neuroendocrine rhythms are especially prominent, and disruptions of circadian rhythms have been closely related to the neurobiology of depression. With the advent of increased research in chronobiology, various pathophysiologic mechanisms have been proposed, including anomalies of sleep architecture, the effects of clock gene polymorphisms in monoamine metabolism, and the deleterious impact of social zeitgebers. The identification of these chronodisruptions has propelled the emergence of several chronotherapeutic strategies, both pharmacological and non-pharmacological, with varying degrees of clinical evidence.

Methods:

The fundamental objective of this review is to integrate current knowledge about the role of chronobiology and depression and to summarize the interventions developed to resynchronize biorhythms both within an individual and with geophysical time.

Results:

We have found that among the non-pharmacological alternatives, triple chronotherapywhich encompasses bright light therapy, sleep deprivation therapy, and consecutive sleep phase advance therapy-has garnered the most considerable scientific interest. On the other hand, agomelatine appears to be the most promising pharmacological option, given its unique melatonergic pharmacodynamics.

Conclusions:

Research in chronotherapy as a treatment for depression is currently booming. Novel interventions could play a significant role in adopting new options for the treatment of depression, with Tripe Cronotherapy standing out as the most promising treatment.

Circadian misalignment increases mood vulnerability in simulated shift work

Night shift work can associate with an increased risk for depression. As night workers experience a 'misalignment' between their circadian system and daily sleep-wake behaviors, with negative health consequences, we investigated whether exposure to circadian misalignment underpins mood vulnerability in simulated shift work. We performed randomized within-subject crossover laboratory studies in non-shift workers and shift workers. Simulated night shifts were used to induce a misalignment between the endogenous circadian pacemaker and sleep/wake cycles (circadian misalignment), while environmental conditions and food intake were controlled. Circadian misalignment adversely impacted emotional state, such that mood and well-being levels were significantly decreased throughout 4 days of continuous exposure to circadian misalignment in non-shift workers, as compared to when they were under circadian alignment (interaction of "circadian alignment condition" vs. "day", mood: p < 0.001; well-being: p < 0.001; adjusted p-values). Similarly, in shift workers, mood and well-being levels were significantly reduced throughout days of misalignment, as compared to circadian alignment (interaction of "circadian alignment condition" vs. "day", mood: p = 0.002; well-being: p = 0.002; adjusted p-values). Our findings indicate that circadian misalignment is an important biological component for mood vulnerability, and that individuals who engage in shift work are susceptible to its deleterious mood effects.

Association between Co-Morbidities and the Prevalence of Excessive Daytime Sleepiness over a Four-Year Period

Excessive daytime sleepiness (EDS) is a common problem in general the Canadian population. It can effect day-to-day activities and is also associated with several health issues. This study aimed to investigate the association between co-morbidities and the prevalence of EDS over a four-year period in adults living in two First Nation communities. Data collected during the First Nations Lung Health Project (FNLHP) conducted in two Cree First Nation communities in Saskatchewan in 2012–2013 (Cycle 1) and 2016 (Cycle 2) were used for this analysis. There were 859 participants aged 18 years and older at baseline (Cycle 1) and 821 participants aged 18 years and older at follow-up (Cycle 2) who completed the interviewer-administered questionnaire. An Epworth Sleepiness Scale (ESS) score > 10 was considered to be abnormal and identified as a case of EDS at both time points. A multilevel logistic regression model using a generalized estimating equations approach was used to analyze the data. The prevalence of EDS at baseline (Cycle 1) was 11.2% (91/815) and 10.0% (80/803) at follow-up (Cycle 2). Based on the predicted model, longitudinal change in the prevalence of EDS was −0.11% for 358 individuals who participated in both cycles. There were 49% males at baseline and 48% males at follow-up. Multivariate regression model results revealed that crowding, shortness of breath, loud snoring, chronic lung disease, depression and gastric reflux were the main significant predictors of EDS. In addition, the interaction between sex and age was significant. Some of the co-morbid conditions were associated with EDS. Therefore, managing such conditions requires considerations in strategies to decrease the prevalence of daytime sleepiness.

Sleep Disturbance Predicts Depression Symptoms in Early Adolescence: Initial Findings From the Adolescent Brain Cognitive Development Study

PURPOSE

The aim of the study was to investigate associations between sleep disturbances and mental health in adolescents.

METHODS

Data are from a national sample of 11,670 U.S. participants (5,594 females, aged 9-10 years, 63.5% white) in the Adolescent Brain Cognitive Development study. Initial longitudinal analyses were conducted for a subset of the sample (n = 4,951). Measures of youth sleep disturbance (disorders of initiating and maintaining sleep, sleep-wake transition disorders, and disorders of excessive somnolence) and "typical" total sleep time (number of hours slept on most nights in the past 6 months) were obtained from the parent-report Sleep Disturbance Scale (Data Release 2.0). Parent-report measures of youth mental health (depression, internalizing, and externalizing behaviors) from the Child Behavior Checklist and typical screen time were included.

RESULTS

At baseline, greater sleep disturbance and shorter total sleep time were associated with greater internalizing, externalizing, and depression scores. After controlling for baseline mental health symptoms, baseline sleep disturbance significantly predicted depression and internalizing and externalizing scores at 1-year follow-up. A significant interaction with sex indicated that the association between disorders of excessive somnolence and depression 1 year later was steeper for girls, compared with boys (p < .001; 95% confidence interval 1.04-3.45).

CONCLUSIONS

Sleep disturbances predicted future mental health, particularly depression in this young sample, highlighting the potential to harness sleep as a tool to mitigate the persistence of depression across early adolescence and potentially prevent an adolescent onset of major depressive disorder.

Prevalence and risk factors of excessive daytime sleepiness in major depression: A study with 703 individuals referred for polysomnography

BACKGROUND

To date, few studies have investigated the prevalence and risk factors of excessive daytime sleepiness (EDS) in major depression. Thus, the aim of the present study was to examine the prevalence and risk factors of EDS in a large sample of individuals with major depression.

METHODS

Data from 703 individuals with major depression were retrospectively collected from the sleep laboratory research database of Erasme Hospital for analysis. A score of > 10 on the Epworth Sleepiness Scale was used as the cut-off for EDS. Logistic regression analyses were conducted to examine the clinical and demographic risk factors of EDS in major depression.

RESULTS

The prevalence of EDS in our sample was 50.8%. Multivariate logistic regression analysis revealed that the following were significant risk factors of EDS in major depression: non-use of short to intermediate half-life benzodiazepine receptor agonists, BMI ≥ 25 kg/m², age < 60 years, C-reactive protein > 7 mg/L, Beck Depression Inventory score ≥ 16, atypical depression, apnea-hypopnea index ≥ 15/h, and use of selective serotonin reuptake inhibitors or serotonin-norepinephrine reuptake inhibitors.

LIMITATIONS

To evaluate EDS, we used the Epworth Sleepiness Scale, which only allows for a subjective measure of daytime sleepiness.

CONCLUSION

EDS is a common symptom in individuals with major depression. In this subpopulation, interventions are possible for most risk factors of EDS, which justifies improved management of this symptom to avoid its negative consequences.

Incidence of Daytime Sleepiness and Associated Factors in Two First Nations Communities in Saskatchewan, Canada

Excessive daytime sleepiness (EDS) is the tendency to sleep at inappropriate times during the day. It can interfere with day-to-day activities and lead to several health issues. The objective of this study was to investigate the association between income, housing conditions, and incidence of EDS in adults living in two Cree First Nations communities. The data for this study involved 317 individuals aged 18 years and older who participated in baseline and follow-up evaluations (after four years) of the First Nations Lung Health Project, which was conducted in Saskatchewan in 2012–2013 and 2016. Both at baseline and follow-up survey after four years, an Epworth Sleepiness Scale (ESS) score >10 was considered to be abnormal. Logistic regression models were used to assess relationships between abnormal ESS and covariates at baseline. In 2016, 7.6% (24/317) of the participants reported an ESS >10 with the mean being 12.8 ± 2.0. For the same group, the mean ESS at baseline was 6.9 ± 2.2. The incidence of subjective EDS based on the ESS >10 was estimated at 7.6% over four years. This study showed an association between incidence of subjective EDS and less money left over at end of the month, having a house in need of repairs, having water or dampness in the past 12 months, and damage caused by dampness.

Personal sleep debt and daytime sleepiness mediate the relationship between sleep and mental health outcomes in young adults

BACKGROUND

Sleep duration and chronotype (i.e., morningness-eveningness) are associated with increased depression and anxiety risk, but differences in individual sleep need and lifestyle may mean these sleep parameters do not present the same risk across all individuals. This study explored the mediating role of sleep debt and daytime sleepiness in the relationship between sleep and mental health symptoms in young adults, a particularly vulnerable population.

METHODS

Young adult university students (n = 2,218) and young adults from the general population in the United States (n = 992) provided estimates of actual and optimal sleep duration, and completed validated measures of sleepiness, chronotype, and depression and anxiety risk. Mediation models examining sleepiness and sleep debt (i.e., difference between optimal and actual sleep) as parallel mediators were tested.

RESULTS

Sleepiness and sleep debt mediated the relationship between short sleep and depression and anxiety risk in the university sample, while sleepiness mediated these relationships in the general population sample. Sleepiness and sleep debt also mediated the impact of evening-type preferences on depression and anxiety risk in university students, but no mediation of this effect was found in young adults from the general population.

CONCLUSIONS

This study reports potential mediating mechanisms related to the increased mental health risk conferred by short sleep and evening chronotype. These results have implications for how primary care physicians assess psychopathology risk, arguing for a focus on the assessment of daytime sleepiness and sleep debt in university populations, while for young adults in the general population, these factors may be less important.

Excessive Daytime Sleepiness Is Associated With Depression Scores, But Not With Sleep-Disordered Breathing in Patients With Cardiovascular Diseases

BACKGROUND

Excessive daytime sleepiness (EDS) is a significant public health concern, with sleep-disordered breathing (SDB) being a common cause. However, their precise relationship in patients with cardiovascular disease (CVD) is unclear. Furthermore, whether comorbid psychological disorders could contribute to EDS remains unknown. We aimed to assess the prevalence of EDS and its related factors, including SDB and depression, in patients with CVD.Methods and Results:We analyzed data from 1,571 patients admitted for various CVDs in a single university hospital (median age, 67 [56-76] years; 29.6% women). We assessed EDS using the Japanese version of the Epworth Sleepiness Scale (ESS; median 6.0 [4.0-9.0]). The presence of EDS (ESS >10, n=297 [18.9%]) did not differ between patients with and without SDB, which was screened with nocturnal pulse oximetry. In contrast, the patients with EDS had higher depression scores (Hospital Anxiety and Depression Scale subscore for depression [HADS-D] and Patient Healthcare Questionnaire [PHQ]-9). The depression scores, measured by HADS-D (odds ratio [OR] 1.14; 95% confidence interval [CI], 1.07-1.22) and PHQ-9 (OR, 1.14; 95% CI, 1.07-1.20) were independent determinants of EDS. These relationships among EDS, SDB, and depression were consistent among the subgroups with cardiovascular comorbidities.

CONCLUSIONS

The presence of EDS is associated with depressive symptoms, but not with SDB, in patients with CVD, suggesting that these patients should be thoroughly assessed for psychological disturbances.

The relationship between depression, daytime napping, daytime dysfunction, and snoring in 0.5 million Chinese populations: exploring the effects of socio-economic status and age

BACKGROUND

Daytime napping has been postulated as both a protective and a risk factor for depression in previous studies. In addition to these conflicting results, research gaps also exist with regard to controlling confounding bias between daytime napping and depression and examining the potential association within the Chinese population. To facilitate the prevention and diagnosis of depression, this study aims to provide insight into the association of daytime napping and depression in 0.5 million Chinese adults by fully controlling confounders, and further examine the modifying effects of socio-economic status (SES) and age.

METHODS

Data were drawn from the baseline of a Chinese cohort study of 0.5 million adults. Depressive status was measured by the Composite International Diagnostic Inventory (CIDI). Logistic regression models were used to examine the association between depression and daytime napping adjusted for SES, sleep-related factors, lifestyle factors and related diseases. Further stratified analyses were conducted to identify the modifying effects of socio-economic status and age.

RESULTS

The odds ratio of depression by daytime napping was 1.15 (95% CI: 1.01-1.31) in females and 1.42 (95% CI: 1.18-1.71) in males. Factors including living in a rural area (OR = 1.31, 95% CI: 1.13-1.52), receiving less education (OR = 1.42, 95% CI: 1.22-1.66), getting married (OR = 1.24, 95% CI: 1.10-1.40) and being 45-65 years old (OR = 1.29, 95% CI: 1.12-1.49) had a modifying effect on daytime napping and depression that could strengthen the association.

CONCLUSIONS

A significantly positive association was found between depression and daytime napping, as well as daytime dysfunction, snoring and both shorter and longer sleep duration. Lower SES and age could possibly modify the association. Further clinical or epidemiological studies are needed to investigate the mechanism and facilitate the prevention of depression.

Chronobiological theories of mood disorder

Major depressive disorder (MDD) remains the most prevalent mental disorder and a leading cause of disability, affecting approximately 100 million adults worldwide. The disorder is characterized by a constellation of symptoms affecting mood, anxiety, neurochemical balance, sleep patterns, and circadian and/or seasonal rhythm entrainment. However, the mechanisms underlying the association between chronobiological parameters and depression remain unknown. A PubMed search was conducted to review articles from 1979 to the present, using the following search terms: "chronobiology," "mood," "sleep," and "circadian rhythms." We aimed to synthesize the literature investigating chronobiological theories of mood disorders. Current treatments primarily include tricyclic antidepressants and selective serotonin reuptake inhibitors, which are known to increase extracellular concentrations of monoamine neurotransmitters. However, these antidepressants do not treat the sleep disturbances or circadian and/or seasonal rhythm dysfunctions associated with depressive disorders. Several theories associating sleep and circadian rhythm disturbances with depression have been proposed. Current evidence supports the existence of associations between these, but the direction of causality remains elusive. Given the existence of chronobiological disturbances in depression and evidence regarding their treatment in improving depression, a chronobiological approach, including timely use of light and melatonin agonists, could complement the treatment of MDD.

Sleep characteristics associated with drowsy driving

OBJECTIVE

The aim of this study was to evaluate sleep characteristics associated with drowsy driving in an adult population.

METHODS

The study subjects consisted of 1675 adults aged 19 years or older who completed a population-based questionnaire survey on sleep habits. Experiences of drowsy driving were obtained from self-reported data. We investigated sleep-related variables including sleep duration, sleep efficiency, chronotype, subjective sleep perception, daytime sleepiness, sleep quality, and snoring. We performed multivariate logistic regression analysis to determine sleep characteristics independently associated with drowsy driving.

RESULTS

The mean age of the subjects was 43.2 years, and 66.3% were men. The prevalence of self-reported drowsy driving was 23.6% (396 of 1675), and 33.1% of subjects experienced dozing at the wheel at least once a month. Multivariate analysis demonstrated that men, office and manual workers, excessive daytime sleepiness, depression, habitual snoring, and perceived insufficient sleep were independently associated with drowsy driving. Subgroup analyses revealed that reduced weekday sleep duration was a risk factor of drowsy driving in adults with perceived sufficient sleep. On the other hand, frequent alcohol drinking significantly increased risk of drowsy driving in the subgroup with perceived sleep insufficiency. Furthermore, ordinal regression analyses confirmed the association between sleep characteristics and drowsy driving across different drowsy driving frequencies.

CONCLUSION

Excessive daytime sleepiness, depression, habitual snoring, and perceived insufficient sleep were sleep-related risk factors for drowsy driving. In addition to maintaining healthy sleep habits, individuals at high risk should be encouraged to evaluate underlying sleep disorders or psychiatric problems to prevent drowsy driving.

Persistent and new-onset daytime sleepiness in pregnant women: A prospective observational cohort study

BACKGROUND

Daytime sleepiness is a frequent complaint in women during pregnancy. It has also been linked to negative obstetric consequences. Although high prevalence of excessive daytime sleepiness throughout pregnancy is well-documented, neither the causes of persistent daytime sleepiness nor new-onset daytime sleepiness during pregnancy have been investigated. Identifying predictive factors may play an important role in the management of daytime sleepiness in pregnant women and improve prenatal care and maternal-fetal outcomes.

OBJECTIVES

To examine first-trimester maternal characteristics associated with the persistence and new-onset daytime sleepiness in pregnant women.

DESIGN

A longitudinal, prospective cohort design.

SETTING

One medical center in Taipei, Taiwan and participating women's homes.

PARTICIPANTS

A total of 204 pregnant women.

METHODS

First-trimester pregnant women recruited from an outpatient obstetric clinic at a medical center provided socio-demographic and health information, wore an actigraphy monitor for 7 days, and completed sleep, mood, and daytime sleepiness questionnaires. Data were collected again when the women were in the second and third trimester.

RESULTS

Thirty-one (15.2%) women experienced excessive daytime sleepiness that persisted across all three trimesters. Nulliparous women and women who snored in the first trimester were 2.28 and 2.10 times more at risk of being classified of persistent daytime sleepiness than multiparous women and women who did not snore in the first trimester, respectively. Thirty-one (15.2%) women developed new-onset daytime sleepiness with advancing gestation. Women were more likely to develop new-onset daytime sleepiness if they worked longer hours per week (OR=1.04, p<0.001), if they reported snoring (OR=6.75, p<0.001), and if they had elevated depressive symptoms in the first trimester of pregnancy (OR=1.09, p=0.01).

CONCLUSIONS

Snoring in the first trimester is involved in both the persistence and new-onset of daytime sleepiness with elevated depressive symptoms related to new-onset daytime sleepiness in pregnant women. Findings suggest that intervention strategies for alleviating daytime sleepiness in pregnant women should focus on managing snoring and symptoms of depression in early trimesters with special attention to nulliparous and employed women.

Excessive Daytime Sleepiness as an Indicator of Depression in Hispanic Americans

INTRODUCTION

Excessive daytime sleepiness (EDS) has been shown to be associated with depression; however, this relationship has not been confirmed among Hispanic Americans.

METHOD

This study examined the link between EDS and depression among Hispanic Americans (N = 411) and explored the potential moderating roles of age, gender, income, education, health status, and acculturation. The Epworth Sleepiness Scale and Patient Health Questionnaire-9 measured EDS and depression, respectively.

RESULTS

Hierarchical linear regression demonstrated that EDS was significantly related to depression. Receiver operating characteristic curve analysis suggested that the Epworth Sleepiness Scale discriminated with adequate sensitivity and specificity between participants with moderately severe depression and those with less severe symptoms. No sociodemographic variables moderated the EDS-depression relationship.

CONCLUSION

These findings suggest that depression should be considered when Hispanic Americans present with EDS.

Ethnic differences in sleep duration and morning-evening type in a population sample

This cross-sectional population study examined associations of sleep duration and morning-evening type with sociodemographic and cardiometabolic disease in adults participating in the UK Biobank study (N = 439 933). Multivariable Poisson regression models of sleep duration and morning-evening type with a robust error variance were generated to estimate adjusted prevalence ratios and their 95% confidence intervals. All models were adjusted for sex, race, college attendance, employment status and age. Twenty five percent of the sample reported short sleep; 27% were morning, 64% intermediate and 9% evening type. Black ethnicity emerged as most strongly associated with sleep behavior. Short sleep was twice as prevalent, and morning versus intermediate type was 1.4 times more prevalent in Black than White participants. The greater prevalence of short sleep and morning type among Blacks suggests that sleep-based approaches to improving cardiometabolic outcomes may require a more multidimensional approach that encompasses adequate sleep and circadian alignment in this population.

Sleep and emotional functions

In this chapter, we review studies investigating the role of sleep in emotional functions. In particular, evidence has recently accumulated to show that brain regions involved in the processing of emotional and reward-related information are activated during sleep. We suggest that such activation of emotional and reward systems during sleep underlies the reprocessing and consolidation of memories with a high affective and motivational relevance for the organism. We also propose that these mechanisms occurring during sleep promote adapted cognitive and emotional responses in the waking state, including overnight performance improvement, creativity, and sexual functions. Activation across emotional-limbic circuits during sleep also appears to promote emotional maturation and the emergence of consciousness in the developing brain.

Distinct pro-vigilant profile induced in rats by the mGluR5 potentiator LSN2814617

While treatment options are available, excessive daytime sleepiness (EDS) remains a significant unmet medical need for many patients. Relatively little rodent behavioural pharmacology has been conducted in this context to assess potential pro-vigilant compounds for their ability to restore functional capacity following experimentally induced sleep loss. Male Wistar rats were prepared for electroencephalographic (EEG) recording and subject to 11 h of sleep restriction using a biofeedback-induced cage rotation protocol. A simple response latency task (SRLT) was used to behaviourally index sleep restriction and the effects of pro-vigilant compounds: modafinil, D-amphetamine, caffeine, and the mGlu5-positive allosteric modulator LSN2814617. Sleep restriction resulted in a consistent, quantified loss of non-rapid eye movement (NREM) and REM sleep that impaired SRLT performance in a manner suggestive of progressive task disengagement. In terms of EEG parameters, all compounds induced wakefulness. Amphetamine treatment further decreased SRLT performance capacity, whereas the other three compounds decreased omissions and allowed animals to re-engage in the task. Caffeine and modafinil also significantly increased premature responses during this period, an effect not observed for LSN2814617. While all compounds caused compensatory sleep responses, the magnitude of compensation observed for LSN2814617 was much smaller than would be predicted to result from the prolongation of wakefulness exhibited. Using simple response latencies to index performance, an mGlu5 PAM dramatically increased wakefulness and improved functional capacity of sleep-restricted animals, without eliciting a proportionate compensatory sleep response. This effect was qualitatively distinct from that of amphetamine, caffeine and modafinil.

Depressive feelings in children with narcolepsy

OBJECTIVES

We aimed to evaluate depressive feelings and their correlations in children and adolescents with narcolepsy collected in national reference centers for narcolepsy.

METHODS

We compared clinical and sleep characteristics of patients with and without depressive symptoms evaluated on the Children's Depression Inventory (CDI).

RESULTS

Our study sample included 88 children (44 boys; 44 de novo patients) with a mean age of 11.9 ± 3.1 years at diagnosis (37.5% were aged ⩽ 10 years). Obesity was found in 59% of the sample and cataplexy was present in 80.7%. The DQB1*0602 allele was positive in 93.5% of our sample. There were 25% of children who had clinically depressive feelings (CDI>16), especially girls older than the age of 10 years. Bivariate associations indicated that depressive feelings were associated with fatigue (48%), hyperactivity (31%), insomnia (16%), and excessive daytime sleepiness (EDS) (14-24%). In the multivariate model adjusted for gender and age, only fatigue explained the variability of the depression score.

CONCLUSION

In our large cohort, high levels of depressive symptoms essentially expressed by fatigue affected 25% of children with narcolepsy. The girls older than 10 years of age were especially vulnerable. The similar prevalence of depressive feelings in treated vs never-treated patients suggests a specific need for diagnosing and managing this symptom in young patients with narcolepsy.

The relationship between excessive daytime sleepiness and depressive and anxiety disorders in women

OBJECTIVE

Excessive daytime sleepiness (EDS) is a common clinical symptom that affects women more than men. However, the association of excessive sleepiness with depressive and anxiety disorders in the broader population is unclear. The aim of this study was, therefore, to examine the association between excessive daytime sleepiness as measured by the Epworth Sleepiness Scale, and depressive and anxiety disorders in a population-based sample of women.

METHODS

Using the Structured Clinical Interview for DSM-IV Disorders (Non-Patient) (SCID-I/NP), 944 women aged 20-97 years (median 49 years, IQR 33-65 years) were assessed for depressive and anxiety disorders as part of the Geelong Osteoporosis Study. EDS was assessed using the Epworth Sleepiness Scale (ESS, cut-off > 10). Lifestyle factors were documented by self-report, height and weight were measured, and socioeconomic status categorised according to the Index of Relative Socio-Economic Advantage and Disadvantage.

RESULTS

Overall, 125 (13.2%) of the women were identified with EDS. EDS was associated with an increased likelihood for both current (OR = 2.11, 95% CI 1.10-4.06) and lifetime history (OR = 1.95, 95% CI 1.28-2.97) of depressive disorders, but not anxiety disorders, independent of age and alcohol consumption. These findings were not explained by antidepressant or sedative use, body mass index, physical activity, smoking, or socioeconomic status.

CONCLUSIONS

These results suggest that excessive daytime sleepiness is associated with current and lifetime depressive, but not anxiety disorders. Clinically, this highlights the need to take into account the possible bidirectional relationship between depressive disorders and excessive sleepiness when assessing mental health issues in patients with EDS.

Daytime sleepiness, sleep disturbance and functioning impairment in bipolar disorder

OBJECTIVE

To verify the prevalence and clinical impact of excessive daytime sleepiness (EDS) in outpatients with bipolar disorder.

METHODS

Eighty-one outpatients with bipolar disorder and 79 healthy control subjects were recruited. Patients were required not to be acutely manic or depressed. We used the Epworth Sleepiness Scale, the Pittsburgh Sleep Quality Index and the Functioning Assessment Short Test to assess sleepiness, sleep problems and functioning, respectively.

RESULTS

Patients had a higher prevalence of sleepiness (40%) than the control group (18%). Sleepiness and sleep disturbance had independent impacts on disability in the multivariable model.

CONCLUSIONS

This study suggests that EDS is a relevant clinical dimension in patients with bipolar disorder. It is a frequent symptom that often overlaps with other sleep disturbances. This study also reveals that once present it has the potential to increase functional impairment.

Complex interaction of circadian and non-circadian effects of light on mood: shedding new light on an old story

In addition to its role in vision, light exerts strong effects on behavior. Its powerful role in the modulation of mood is well established, yet remains poorly understood. Much research has focused on the effects of light on circadian rhythms and subsequent interaction with alertness and depression. The recent discovery of a third photoreceptor, melanopsin, expressed in a subset of retinal ganglion cells, allows major improvement of our understanding of how photic information is processed. Light affects behavior in two ways, either indirectly through the circadian timing system, or directly through mechanisms that are independent of the circadian system. These latter effects have barely been studied in regard to mood, but recent investigations on the direct effects of light on sleep and alertness suggest additional pathways through which light could influence mood. Based on our recent findings, we suggest that light, via melanopsin, may exert its antidepressant effect through a modulation of the homeostatic process of sleep. Further research is needed to understand how these mechanisms interplay and how they contribute to the photic regulation of mood. Such research could improve therapeutic management of affective disorders and influence the management of societal lighting conditions.

Depressive symptoms and sleepiness among Latino farmworkers in eastern North Carolina

Depression and sleepiness are both risk factors for occupational accidents and unintentional injury. Relatively little is known about the experiences of these risk factors in the immigrant Latino farmworker population. This analysis uses prospective panel data from a sample of Latino farmworkers in eastern North Carolina that were collected at monthly intervals during the 2008 agricultural season to (1) describe depressive symptoms and daytime sleepiness among immigrant Latino farmworkers across the agricultural season; (2) delineate associations of depressive symptoms with sleepiness across time; and (3) determine whether depressive symptoms precede sleepiness, or if sleepiness precedes depressive symptoms. Results indicated that 45% of farmworkers experienced elevated depressive symptoms across the season, whereas 20% experienced elevated sleepiness. Elevated depressive symptoms were more common among farmworkers living in barracks, and less common among those living in trailers. Sleepiness was more common among women than men. There was no evidence that depressive symptoms contributed to sleepiness, or that sleepiness contributed to depressive symptoms. The pattern of results suggests that a substantial proportion of Latino farmworkers experience levels of depressive symptoms or sleepiness that places them at risk for occupational accident or unintentional injury. The results also suggest that depressive symptoms and sleepiness do not cause each other; rather, the association of depressive symptoms with sleepiness hints at the possibility of a common physiologic mechanism such as circadian disruption.

[Affective disorders: News in chronobiological models]

Good news on chronobiological models of affective disorders are coming from a therapeutic innovation in the field of antidepressive action. Coming back to fundamentals by reconsidering the importance of the role of biological rhythms impairment in dysthymic pathology, a new interest bored on studies exploring short periodicities, so-called "ultradian" ones, on the basis of pharmacodynamics in the concept of therapeutic "window" of administration. The priority of circadian rhythms due to the major external biological desynchronization in depression, as well as the importance of sleep and alertness pathology, the spectacular relief of the depressive mood upon sleep deprivation, and the strong reduction of sleep need in mania, delayed exploration of ultradian exaltation of harmonic circadian components, marking a "buzz" of rhythmic structure and calling a "chronobiotic compound" which would be able to apply a "reset" to the temporal organisation. Another return to the origin leads to the experimental genomics, informing nor the "depressivity" but manic pathogenesis, in a mouse gene model which queries on the share of addictive and affective disorders.