Effectiveness of enhanced cognitive behavior therapy for bulimia nervosa in Japan: a randomized controlled trial protocol

Although fatigue is a common and distressing symptom in cancer survivors, the mechanism of fatigue is not fully understood. Therefore, this study aims to investigate the relation between the fatigue and mindfulness of breast cancer survivors using anxiety, depression, pain, loneliness, and sleep disturbance as mediators. Path analysis was performed to examine direct and indirect associations between mindfulness and fatigue. Participants were breast cancer survivors who visited a breast surgery department at a university hospital in Japan for hormonal therapy or regular check-ups after treatment. The questionnaire measured cancer-related-fatigue, mindfulness, anxiety, depression, pain, loneliness, and sleep disturbance. Demographic and clinical characteristics were collected from medical records. Two-hundred and seventy-nine breast cancer survivors were registered, of which 259 answered the questionnaire. Ten respondents with incomplete questionnaire data were excluded, resulting in 249 participants for the analyses. Our final model fit the data well (goodness of fit index = .993; adjusted goodness of fit index = .966; comparative fit index = .999; root mean square error of approximation = .016). Mindfulness, anxiety, depression, pain, loneliness, and sleep disturbance were related to fatigue, and mindfulness had the most influence on fatigue (β = − .52). Mindfulness affected fatigue not only directly but also indirectly through anxiety, depression, pain, loneliness, and sleep disturbance. The study model helps to explain the process by which mindfulness affects fatigue. Our results suggest that mindfulness has both direct and indirect effects on the fatigue of breast cancer survivors and that mindfulness can be used to more effectively reduce their fatigue. It also suggests that health care professionals should be aware of factors such as anxiety, depression, pain, loneliness, and sleep disturbance in their care for fatigue of breast cancer survivors. This study was registered in the University Hospital Medical Information Network Clinical Trials Registry (UMIN number. 000027720) on June 12, 2017.     

A Population-Based Investigation into the Self-Reported Reasons for Sleep Problems

Typologies of sleep problems have usually relied on identifying underlying causes or symptom clusters. In this study the value of using the patient''s own reasons for sleep disturbance are explored. Using secondary data analysis of a nationally representative psychiatric survey the patterning of the various reasons respondents provided for self-reported sleep problems were examined. Over two thirds (69.3%) of respondents could identify a specific reason for their sleep problem with worry (37.9%) and illness (20.1%) representing the most commonly reported reasons. And while women reported more sleep problems for almost every reason compared with men, the patterning of reasons by age showed marked variability. Sleep problem symptoms such as difficulty getting to sleep or waking early also showed variability by different reasons as did the association with major correlates such as worry, depression, anxiety and poor health. While prevalence surveys of ‘insomnia’ or ‘poor sleep’ often assume the identification of an underlying homogeneous construct there may be grounds for recognising the existence of different sleep problem types particularly in the context of the patient''s perceived reason for the problem.     

Association between pro- and anti-inflammatory cytokine genes and a symptom cluster of pain, fatigue, sleep disturbance, and depression

Because multiple symptoms associated with "sickness behavior" have a negative impact on functional status and quality of life, increased information on the mechanisms that underlie inter-individual variability in this symptom experience is needed. The purposes of this study were to determine: if distinct classes of individuals could be identified based on their experience with pain, fatigue, sleep disturbance, and depression; if these classes differed on demographic and clinical characteristics; and if variations in pro- and anti- inflammatory cytokine genes were associated with latent class membership. Self-report measures of pain, fatigue, sleep disturbance, and depression were completed by 168 oncology outpatients and 85 family caregivers (FCs). Using latent class profile analysis (LCPA), three relatively distinct classes were identified: those who reported low depression and low pain (83%), those who reported high depression and low pain (4.7%), and those who reported high levels of all four symptoms (12.3%). The minor allele of IL4 rs2243248 was associated with membership in the "All high" class along with younger age, being White, being a patient (versus a FC), having a lower functional status score, and having a higher number of comorbid conditions. Findings suggest that LPCA can be used to differentiate distinct phenotypes based on a symptom cluster associated with sickness behavior. Identification of distinct phenotypes provides new evidence for the role of IL4 in the modulation of a sickness behavior symptom cluster in oncology patients and their FCs.     

Psychological Health in a Population of Australian Cat Owners

Abstract

Ninety-two cat owners, and 70 non-pet subjects were surveyed to determine the relationship between psychological health and pet ownership. The survey employed measures of general psychological health, depression, state and trait anxiety, sleep disturbance, nurturance, attitudes toward pets, social desirability, and a life events inventory. The study hypothesized that cat owners would be more psychologically healthy than non-pet owners and that this difference would be reflected in the cat owners having lower scores on the measures of general psychological health, depression, anxiety, and sleep disturbance. The study also proposed that cat owners would be more nurturing and have a more favorable attitude toward pets than non-pet owners. Findings showed that the cat owners had significantly lower scores for general psychological health, indicating a lower level of psychiatric disturbance, and could be considered to have better psychological health than the non-pet subjects. The cat owners also had significantly higher pet attitude scores than non-pet subjects, indicating a more favorable attitude toward pets. No significant differences were found for depression, anxiety, sleep disturbance, nurturance, social desirability, or life events for cat owners and non-pet subjects.     

ASSOCIATIONS BETWEEN CHRONOTYPE,SLEEP QUALITY,SUICIDALITY, AND DEPRESSIVE SYMPTOMS IN PATIENTS WITH MAJOR DEPRESSION AND HEALTHY CONTROLS

Research interest concerning associations between sleep characteristics and suicidality in psychopathology has been growing. However, possible linkages of suicidality to sleep characteristics in terms of sleep quality and chronotypes among depressive patients have not been well documented. In the current study, the authors investigated the possible effects of sleep quality and chronotype on the severity of depressive symptoms and suicide risk in patients with depressive disorder and healthy controls. The study was conducted on 80 patients clinically diagnosed with major depression and 80 healthy subjects who were demographically matched with the patient group. All participants completed a questionnaire package containing self-report measures, including the Beck Depression Inventory (BDI), Pittsburgh Sleep Quality Index (PSQI), Morningness–Eveningness Questionnaire (MEQ), and Suicide Ideation Scale (SIS), and subjects were interviewed with the suicidality section of the Mini-International Neuropsychiatric Interview (MINI). Results are as follows: (a) logistic regression analyses revealed that poor sleep quality and depression symptom severity significantly predicted onset of major depression; (b) morningness-type circadian rhythm may play as a significant relief factor after onset of major depression; (c) sleep variables of chronotype and sleep quality did not significantly predict suicide ideation after controlling for depressive symptoms in the major depression group; and (d) suicide ideation and poor sleep quality were antecedents of depression symptom severity in patients with major depression, and in healthy controls. Findings are discussed under the theoretical assumptions concerning possible relations between chronotype, sleep quality, depression, and suicidality. (Author correspondence: dryavuzselvi@yahoo.com)     

Critical slowing down as an early warning of transitions in episodes of bipolar disorder: A simulation study based on a computational model of circadian activity rhythms

Bipolar disorder is characterized by repeated episodes of mania and depression, and can be understood as pathological complex system behaviour involving cognitive, affective and psychomotor disturbance. Accurate prediction of episode transitions in the long-term pattern of mood changes in bipolar disorder could improve the management of the disorder by providing an objective early warning of relapse. In particular, circadian activity changes measured via actigraphy may contain clinically relevant signals of imminent systemic dysregulation. In this study, we propose a mathematical index to investigate the correlation between apparently irregular circadian activity rhythms and critical transitions in episodes of bipolar disorder. Not only does the proposed index illuminate the effects of pharmacological and psychological therapies in control over the state, but it also provides a framework to understand the dynamic (or state-dependent) control strategies. Modelling analyses using our new approach suggest that key clinical goals are minimizing side effects of mood stabilizers as well as increasing the efficiency of other therapeutic strategies.     

Effects of lifestyle, personality, symptoms of anxiety and depression, and genetic predisposition on subjective sleep disturbance and sleep pattern.

The effects on sleep pattern ('short-sleep' versus 'long-sleep') and subjective sleep disturbance of genotype, personality, symptoms of anxiety and depression, and lifestyle, were examined using survey data on a clinically unselected sample of adult Australian twin pairs, aged 17-88 years. When the effects of genotype, personality and symptoms were ignored, lifestyle variables appeared to account for roughly 4% of the variance in sleep disturbance, and 9% of the variance in sleep pattern. Significant genetic effects on sleep disturbance and sleep pattern were found, which were only partly explained by the effects of personality and symptoms of anxiety and depression. Much of the association between sleep disturbance and lifestyle appeared to be explained by separate effects of personality and symptoms of anxiety and depression on sleep and lifestyle ('genotype-risk-factor correlation'). There was little evidence for genetically determined differences in sensitivity to the lifestyle variables ('genotype x risk-factor interaction').     

Chronic stress, catecholamines, and sleep disturbance at Three Mile Island

The present study was concerned with the relationship between chronic stress and sleep disturbance. Previous research has provided evidence of chronic stress responding among people living near the Three Mile Island nuclear generating facility. Compared to control subjects, the TMI group has exhibited greater symptom reporting, poorer performance on behavioral measures of concentration, and elevated levels of urinary norepinephrine and epinephrine. Other research has suggested a relationship between arousal and insomnia. The extent to which stress and sleep disturbances were experienced by residents at TMI was examined and compared to levels of stress and sleep disturbance among a group of control subjects. The relationship between stress and sleep disturbances was also examined. Results indicated that TMI area residents exhibited more stress than the controls and reported greater disturbance of sleep. Modest relationships among stress and sleep measures suggested that the symptoms of stress measured in this study were not primary determinants of sleep problems.     

Risk Factors Associated with Sleep Disturbance following Traumatic Brain Injury: Clinical Findings and Questionnaire Based Study

Background

Sleep disturbance is very common following traumatic brain injury (TBI), which may initiate or exacerbate a variety of co-morbidities and negatively impact rehabilitative treatments. To date, there are paradoxical reports regarding the associations between inherent characteristics of TBI and sleep disturbance in TBI population. The current study was designed to explore the relationship between the presence of sleep disturbance and characteristics of TBI and identify the factors which are closely related to the presence of sleep disturbance in TBI population.

Methods

98 TBI patients (72 males, mean age ± SD, 47 ± 13 years, range 18-70) were recruited. Severity of TBI was evaluated based on Glasgow Coma Scale (GCS). All participants performed cranial computed tomography and were examined on self-reported sleep quality, anxiety, and depression.

Results

TBI was mild in 69 (70%), moderate in 15 (15%) and severe in 14 (15%) patients. 37 of 98 patients (38%) reported sleep disturbance following TBI. Insomnia was diagnosed in 28 patients (29%) and post-traumatic hypersomnia in 9 patients (9%). In TBI with insomnia group, 5 patients (18%) complained of difficulty falling asleep only, 8 patients (29%) had difficulty maintaining sleep without difficulty in initial sleep and 15 patients (53%) presented both difficulty falling asleep and difficulty maintaining sleep. Risk factors associated with insomnia were headache and/or dizziness and more symptoms of anxiety and depression rather than GCS. In contrast, GCS was independently associated with the presence of hypersomnia following TBI. Furthermore, there was no evidence of an association between locations of brain injury and the presence of sleep disturbance after TBI.

Conclusion

Our data support and contribute to a growing body of evidence which indicates that TBI patients with insomnia are prone to suffer from concomitant headache and/or dizziness, report more symptoms of anxiety and depression and severe TBI patients are likely to experience hypersomnia.     

The unique challenges of managing depression in mid-life women

Throughout most of their lives, women are at a greater risk of becoming depressed than men. Some evidence suggests that this heightened risk is associated with increased sensitivity to the hormonal changes that occur across the female reproductive lifecycle. For some women, the peri-menopause and early post-menopausal years may constitute a “window of vulnerability” during which challenging physical and emotional discomforts could result in significant impairment in functioning and poorer quality of life. A number of biological and environmental factors are independent predictors for depression in this population, including the presence of hot flashes, sleep disturbance, history of severe premenstrual syndrome or postpartum blues, ethnicity, history of stressful live events, past history of depression, body mass index and socioeconomic status. This paper explores the current knowledge on the complex associations between mood changes and aging in women. More specifically, the biological aspects of reproductive aging and their impact on mood, psychosocial factors, lifestyle, and overall health are reviewed. In addition, evidence-based hormonal and non-hormonal therapies for the management of depression and other complaints in midlife women are discussed. Ultimately, this article should help clinicians and health professionals to address a challenging clinical scenario: a preventive and effective strategy for the management of depression in the context of the menopausal transition and beyond.     

Melatonin and clinical application.

A review of the different publications dealing with melatonin in humans shows that this field has been very active in the last few years. Normative melatonin values have been defined. Various relationships between melatonin and other traits have been studied, such as sleep, circadian rhythm, surgical stress and anaesthesia. Age-related melatonin studies and melatonin during depression and other psychiatric disorders have been reviewed. Finally, some studies have been performed to use melatonin as a medication for sleep disturbance in depression, for jet-lag and as a skin protector for ultraviolet light.     

Criterion validity of the Pittsburgh Sleep Quality Index: Investigation in a non-clinical sample

The objective of this study was to investigate the reliability and validity of the Pittsburgh Sleep Quality Index (PSQI) in a non-clinical sample consisting of younger and older adults. There has been little research validating the PSQI with respect to multinight recording as with actigraphy, and more validation is needed in samples not specifically selected for clinical disturbance. Also, the degree to which the PSQI scores may reflect depressive symptoms versus actual sleep disturbance remains unclear. One-hundred and twelve volunteers (53 younger and 59 older) were screened for their ability to perform treadmill exercises; inclusion was not based on sleep disturbance or depression. Internal homogeneity was evaluated by correlating PSQI component scores with the global score. Global and component scores were correlated with a sleep diary, actigraphy, and centers for epidemiological studies - depression scale scores to investigate criterion validity. Results showed high internal homogeneity. PSQI global score correlated appreciably with sleep diary variables and the depression scale, but not with any actigraphic sleep variables. These results suggest that the PSQI has good internal homogeneity, but may be less reflective of actual sleep parameters than a negative cognitive viewpoint or pessimistic thinking. The sleep complaints measured may often be more indicative of general dissatisfaction than of any specifically sleep-related disturbance.     

Sleep and intellectual functioning in the elderly: the role of sleep quality and apnea--literature survey

In both relatively healthy and in demented elderly people mental abilities and sleep quality decrease in becoming older and nocturnal respiratory disturbance increases. Perhaps there is an association between sleep and cognition. The hypothesis that specific sleep phenomena are necessary to assure an adequate level of cognitive functioning is called the sleep cognition hypothesis. In this article the findings of research in older people are reviewed. 23 research reports were found in which sleep was measured with polysomnography. The findings in relatively healthy older people do not suggest a strong association between sleep and cognition nor a causal effect between a specific cognitive dysfunction and a specific sleep variable. The findings in demented older people concerning sleep and cognition are inconsistent. In relatively healthy older people a significant correlation between nocturnal respiratory disturbance and cognitive functioning was seldom found, whereas in demented older people a clear association was shown. Therefore, in demented older people prudence is necessary in prescribing psychopharmaca because these can enhance the appearance of sleep apneas.     

Daytime sleepiness in the obese: not as simple as obstructive sleep apnea

Objective: Excessive daytime sleepiness is a common symptom in obese patients, but what drives this condition is unclear. The objective was to look for clinical, anthropometric, biochemical, and polysomnographic predictors of excessive daytime sleepiness as measured by the Epworth Sleepiness Scale (ESS) in obese patients. Research Methods and Procedures: The ESS questionnaire was completed by 1055 consecutive patients presenting for obesity surgery. Those at high risk for obstructive sleep apnea (n = 331) had diagnostic overnight polysomnography preoperatively. All patients had preoperative clinical, hematologic, and biochemical measurements and completed multiple questionnaires. Results: There was no significant relationship between ESS score and any measure of diagnostic polysomnography factors, including total apnea hypopnea index. Subtle increases in ESS scores were reported in men, older patients, and those with type 2 diabetes. However, general demographic, anthropometric, and biochemical measures of the metabolic syndrome explained only 3% of ESS score variance, and inflammatory markers of C‐reactive protein and total white cell count were not predictive. Poor Short Form‐36 energy scores (b = ?0.18, p < 0.001) and high Beck Depression Inventory scores were predictive of higher ESS scores (b = 0.15, p < 0.001) and, along with increasing age and male gender, explained 10% of variance. Symptoms related to disturbed nocturnal sleep explained 30% of variance. Conclusion: In severely obese subjects, increased daytime sleepiness does not seem to be driven by obstructive sleep apnea, the degree of obesity, or anthropometric, metabolic, or inflammatory markers of the metabolic syndrome. It is, however, associated with poor energy, symptoms of depression, and symptoms of nocturnal sleep disturbance.     

The impact of a delayed sleep–wake schedule on depression is greater in women – A web-based cross-sectional study in Japanese young adults

Sleep-related problems, such as symptoms of insomnia, daytime sleepiness, shorter sleep duration, or a delayed sleep–wake schedule, are known to be risk factors for depression. In general, depression is more prevalent in women than in men, but sleep-related problems do not necessarily show similar gender predominance. Hence, it can be speculated that the impact of sleep-related problems on the development process of depression differs between genders; however, so far, few studies have focused on this issue. The aim of this study was to clarify gender differences in the rates of depression of people with the above sleep-related problems, and to examine gender differences in factors associated with depression in Japanese young adults. A web-based questionnaire survey comprising assessments of demographic variables, sleep-related variables (bed time, wake time, sleep onset latency, frequency of difficulty in initiating sleep and that in maintaining sleep, i.e. symptom components of insomnia, and daytime sleepiness), and the 12-item version of the Center for Epidemiologic Studies Depression Scale was administered to 2502 participants (males:females?=?1144:1358, age range?=?19–25 years). Female predominance in the rate of depression was observed only in subjects with a delayed sleep–wake schedule (χ²₍₁₎?=?15.44, p?<?0.001). In men, daytime sleepiness and difficulty in initiating sleep were significantly associated with depression (odds ratio [OR]?=?2.39, 95% confidence interval [CI]?=?[1.69, 3.39], p?<?0.001; OR?=?3.50, 95% CI?=?[2.29, 5.35], p?<?0.001, respectively), whereas in women, significant associations were found between depression and a delayed sleep–wake schedule (OR?=?1.75, 95% CI?=?[1.28, 2.39], p?<?0.001), daytime sleepiness (OR?=?2.13, 95% CI?=?[1.60, 2.85], p?<?0.001), and difficulty in initiating sleep (OR?=?4.37, 95% CI?=?[3.17, 6.03], p?<?0.001). These results indicate that in younger generations, the impact of a delayed sleep–wake schedule on the development of depression is greater in women; specifically, women are vulnerable to depression when they have an eveningness-type lifestyle, which is possibly attributable to the female-specific intrinsic earlier and shorter circadian rhythm. These results suggest the necessity of gender-based approaches to treating sleep-related problems for alleviating or preventing depressive symptoms in young adults.     

Correlation of sleep disturbances, anxiety and depression in Croatian war veterans with posttraumatic stress disorder

The aim of the study was to examine the relationships between global sleep quality and its specific components and Posttraumatic Stress Disorder (PTSD) symptom severity questionnaire. We also researched whether sleep quality and sleep disturbances differed among groups of PTSD based on symptom severity categories. This study was conducted on the sample of 120 Croatian war veterans with PTSD. The following self-report instruments were used: Pittsburgh Sleep Quality Index, the Pittsburgh Sleep Quality Index Addendum for PTSD, the Mississippi Scale for Combat-Related PTSD, the Spielberger State and Trait Anxiety Inventory and the Beck Depression Inventory. There were statistically significant differences between the three PTSD severity groups on general nervousness (PSQI-A variable), where patients with extremely severe PTSD have more symptoms of general nervousness than groups with severe or moderate PTSD. Differences were found between PTSD severity groups in episodes of terror and acting-out dreams, where patients with extremely severe PTSD have more symptoms of episodes of terror and acting-out dreams than groups with severe or moderate PTSD. Sleep quality was significantly correlated with state anxiety, trait anxiety, and depression, indicating that with decrease of anxiety and depression, sleep quality improves. Sleep latency was positively correlated with both state and trait anxiety. There wasn't any significant correlation between sleep latency and depression. Study suggests that sleep disturbances are equally severe across groups of veterans based on PTSD severity and that the severity of sleep disturbances is significantly related to severity of anxiety and depression symptoms.     

Relationship of 30‐Year Changes in Obesity to Sleep‐Disordered Breathing in the Western Collaborative Group Study

Objective: Obesity is an important etiologic factor in sleep‐disordered breathing (SDB), but the extent to which changes in obesity across adult life contribute independently to SDB in old age has not been studied. In this study, we examined the association between changes in obesity from midlife to late adulthood and overnight recording of respiration during sleep. Research Methods and Procedures: Subjects in this study are from the Western Collaborative Group Study, a longitudinal cardiovascular epidemiological study that began in 1960 through 1961. Overnight sleep recordings were obtained from 281 male participants in the 1995 through 1996 follow‐up of the Western Collaborative Group Study. Subjects were 75 to 91 years old when assessed for SDB as indexed by the respiratory disturbance index and an oxygen desaturation index (O₂DI). Long‐term changes in anthropometrics were evaluated and examined in relation to SDB severity. Results: Over the 30 years of follow‐up, body mass index and waist circumference increased significantly for this sample and were associated with SDB severity as indexed by respiratory disturbance index and O₂DI. Waist circumference at baseline and gain in waist circumference over the 30 years of follow‐up (both p = 0.01) were significantly and independently associated with SDB severity as assessed by O₂DI. However, percentage of variance as accounted for by waist circumference was modest. Discussion: This study supports the hypothesis that gain in waist circumference over adult life is significantly associated with SDB severity in older men.     

Evidence of Associations between Cytokine Genes and Subjective Reports of Sleep Disturbance in Oncology Patients and Their Family Caregivers

The purposes of this study were to identify distinct latent classes of individuals based on subjective reports of sleep disturbance; to examine differences in demographic, clinical, and symptom characteristics between the latent classes; and to evaluate for variations in pro- and anti-inflammatory cytokine genes between the latent classes. Among 167 oncology outpatients with breast, prostate, lung, or brain cancer and 85 of their FCs, growth mixture modeling (GMM) was used to identify latent classes of individuals based on General Sleep Disturbance Scale (GSDS) obtained prior to, during, and for four months following completion of radiation therapy. Single nucleotide polymorphisms (SNPs) and haplotypes in candidate cytokine genes were interrogated for differences between the two latent classes. Multiple logistic regression was used to assess the effect of phenotypic and genotypic characteristics on GSDS group membership. Two latent classes were identified: lower sleep disturbance (88.5%) and higher sleep disturbance (11.5%). Participants who were younger and had a lower Karnofsky Performance status score were more likely to be in the higher sleep disturbance class. Variation in two cytokine genes (i.e., IL6, NFKB) predicted latent class membership. Evidence was found for latent classes with distinct sleep disturbance trajectories. Unique genetic markers in cytokine genes may partially explain the interindividual heterogeneity characterizing these trajectories.     

A meta‐review of “lifestyle psychiatry”: the role of exercise,smoking, diet and sleep in the prevention and treatment of mental disorders

There is increasing academic and clinical interest in how “lifestyle factors” traditionally associated with physical health may also relate to mental health and psychological well‐being. In response, international and national health bodies are producing guidelines to address health behaviors in the prevention and treatment of mental illness. However, the current evidence for the causal role of lifestyle factors in the onset and prognosis of mental disorders is unclear. We performed a systematic meta‐review of the top‐tier evidence examining how physical activity, sleep, dietary patterns and tobacco smoking impact on the risk and treatment outcomes across a range of mental disorders. Results from 29 meta‐analyses of prospective/cohort studies, 12 Mendelian randomization studies, two meta‐reviews, and two meta‐analyses of randomized controlled trials were synthesized to generate overviews of the evidence for targeting each of the specific lifestyle factors in the prevention and treatment of depression, anxiety and stress‐related disorders, schizophrenia, bipolar disorder, and attention‐deficit/hyperactivity disorder. Standout findings include: a) convergent evidence indicating the use of physical activity in primary prevention and clinical treatment across a spectrum of mental disorders; b) emerging evidence implicating tobacco smoking as a causal factor in onset of both common and severe mental illness; c) the need to clearly establish causal relations between dietary patterns and risk of mental illness, and how diet should be best addressed within mental health care; and d) poor sleep as a risk factor for mental illness, although with further research required to understand the complex, bidirectional relations and the benefits of non‐pharmacological sleep‐focused interventions. The potentially shared neurobiological pathways between multiple lifestyle factors and mental health are discussed, along with directions for future research, and recommendations for the implementation of these findings at public health and clinical service levels.     

A Prospective Study of Seasonal Variation in Shift‐Work Tolerance

Seasonal effects on shift‐work tolerance were assessed using the Standardized Shiftwork Index and the 21‐item Hamilton Depression Scale. Participants (N=88) mainly worked a two‐day, two‐night, four‐off rotation with 12 h shifts changing at 06∶00 and 18∶00 h in Vancouver, Canada. At this latitude (～49° N), daylength varies seasonally from ～16 to ～8 h, and both daily commutes occur in the dark in mid‐winter and in sunlight in mid‐summer. Questionnaires were completed twice, near the summer and winter solstices (order counterbalanced). Outcome variables were mood, general psychological health, sleep quality, chronic fatigue, physical health, job satisfaction, and social and domestic disruption. Of these, general psychological health and mood were significantly worse in winter, while sleep was more disturbed in summer. In winter, 31% exceeded the cutoff for psychological distress, and >70% scored in the higher than normal range for depressive symptoms. In summer, the proportions dropped to 19% and 53%, respectively. Measures of physical health and psychosocial well‐being showed no seasonal effects. Relationships among explanatory and outcome variables, assessed by linear regression and canonical correlations, were also stable across season. Neuroticism was the strongest predictor of tolerance to shift work. Age was predictive only of sleep disturbance in both summer and winter. These results indicate that time of year can affect important outcome measures in shift‐work assessment and intervention studies. The high average scores on measures of psychological distress and depression in winter suggest that at northern latitudes, some shift schedules may increase the risk of seasonal‐type depression.