Adverse changes in mood and cognitive performance of house officers after night duty.

The effects of long hours of work by junior doctors are the subject of growing concern. Experimental investigations of the effects of night duty on young doctors are few and have given inconclusive results. To measure the effects of long hours of work and reduced sleep on cognitive performance and mood 20 house officers (14 men and six women; mean age 25, range 24-35) were examined for 35 minutes in one session towards the end of a normal working day and in a second session at the same time after working for up to 31 continuous hours with reduced sleep. The order of the sessions was counterbalanced across the subjects. Each session comprised a series of cognitive tests: choice reaction time, vigilance reaction time, and haptic sorting tests and completion of a profile of mood states and a general questionnaire. After night duty there was a significant slowing in cognitive processing together with a decline in reaction times in the vigilance test. Loss of sleep contributed only to increased variability in the choice reaction time. Significant deleterious changes in mood after night duty occurred in all the mood scales after night duty. Continuous working may adversely affect the cognitive function and mood to the detriment of the welfare of doctors and their patients.     

Testosterone, cortisol, and mood in a sports team competition

In humans, hormonal responses to winning/losing and their relationships to mood and status change have mostly been examined in individual athletic competitions. In this study, the salivary testosterone (T) and cortisol (C) and mood responses to a real match between two professional basketball teams were investigated. Data about individuals' contributions to outcome, performance appraisal, and attribution of outcome to internal/external factors were also collected. Results did not show statistically significant different T and C responses depending on the outcome. Negative mood was significantly enhanced, especially in the losers, while winners showed a better appraisal of team performance and a more internal attribution. T response did not show a significant relationship with mood changes, but it correlated positively with the "score/time playing" ratio, an indicator of individual participation in the outcome. Furthermore, T response correlated negatively with external attribution in winners and positively in losers. These results indicate that in a real, highly competitive situation, T changes are not directly a response to the outcome, but rather to the contribution the individual makes to it and to the causes he attributes.     

The Dynamics of Mood and Coping in Bipolar Disorder: Longitudinal Investigations of the Inter-Relationship between Affect,Self-Esteem and Response Styles

Background

Previous research has suggested that the way bipolar patients respond to depressive mood impacts on the future course of the illness, with rumination prolonging depression and risk-taking possibly triggering hypomania. However, the relationship over time between variables such as mood, self-esteem, and response style to negative affect is complex and has not been directly examined in any previous study – an important limitation, which the present study seeks to address.

Methods

In order to maximize ecological validity, individuals diagnosed with bipolar disorder (N = 48) reported mood, self-esteem and response styles to depression, together with contextual information, up to 60 times over a period of six days, using experience sampling diaries. Entries were cued by quasi-random bleeps from digital watches. Longitudinal multilevel models were estimated, with mood and self-esteem as predictors of subsequent response styles. Similar models were then estimated with response styles as predictors of subsequent mood and self-esteem. Cross-sectional associations of daily-life correlates with symptoms were also examined.

Results

Cross-sectionally, symptoms of depression as well as mania were significantly related to low mood and self-esteem, and their increased fluctuations. Longitudinally, low mood significantly predicted rumination, and engaging in rumination dampened mood at the subsequent time point. Furthermore, high positive mood (marginally) instigated high risk-taking, and in turn engaging in risk-taking resulted in increased positive mood. Adaptive coping (i.e. problem-solving and distraction) was found to be an effective coping style in improving mood and self-esteem.

Conclusions

This study is the first to directly test the relevance of response style theory, originally developed to explain unipolar depression, to understand symptom changes in bipolar disorder patients. The findings show that response styles significantly impact on subsequent mood but some of these effects are modulated by current mood state. Theoretical and clinical implications are discussed.     

The truth about doctors' handwriting: a prospective study.

OBJECTIVES: To determine whether doctors have worse handwriting than other health professionals. DESIGN: Comparison of handwriting samples collected prospectively in a standardised 10 seconds'' task. SETTING: Courses on quality improvement. SUBJECTS: 209 health care professionals attending the courses, including 82 doctors. MAIN OUTCOME MEASURES: Legibility rated on a four-point scale by four raters. RESULTS: The handwriting of doctors was no less legible than that of non-doctors. Significantly lower legibility than average was associated with being an executive and being male. Overall legibility scores were normally distributed, with median legibility equivalent to a rating between "fair" and "good." CONCLUSION: This study fails to support the conventional wisdom that doctors'' handwriting is worse than others.'' Illegible writing is, however, an important cause of waste and hazard in medical care, but efforts to improve the safety and efficiency of written communication must approach the problem systemically- and assume that the problems are in inherent in average human writing-rather than treating doctors as if they were a special subpopulation.     

Reasons for doctors' career choice and change of choice

In a study of doctors who qualified from British medical schools in 1974 and 1977, which was carried out five to 11 years after graduation, frequent changes of career choice were found. Most of these changes occurred at a relatively early stage. There was a shift of choices towards general practice, and to a lesser extent other specialties, predominantly from medicine, surgery, and paediatrics. Great importance was attached to self evaluation of aptitude and ability as a factor in determining the choice of career and also to awareness of promotion prospects and difficulties. The absence of or failure of careers advice to influence choice of career was notable as was the little importance attached to financial circumstances. Domestic circumstances were an important determinant, particularly for general practice and for women doctors. Among those who qualified in 1980 and 1983, at the preregistration stage, domestic circumstances were less important than they were for slightly older doctors, but undergraduate experience had a greater influence. Contact with a particular teacher or department was not, however, a notable element in this.     

Mood effects of weather conditions of the Zagreb population, Croatia

The level of information on biometeorologic reports and mood effects of weather conditions on the Zagreb population were assessed in a sample of 782 subjects. Only 103 (13.2%) study subjects had not been informed on biometeorologic reports. Mood effects of weather conditions were reported by more than 76% of study subjects, 18.3% of them reporting meteorosensitivity. Meteorosensitivity showed a female predominance, and increased with age and level of education. 88% of chronic patients reported discomforts caused by changes in atmospheric conditions. Apathy and sleepiness were the most common mood changes associated with weather changes, whereas humid weather was indicated as a weather type that caused most discomforts in study subjects.     

The Association of Types of Training and Practice Settings with Doctors’ Empathy and Patient Enablement among Patients with Chronic Illness in Hong Kong

Background

The increase in non-communicable disease (NCD) is becoming a global health problem and there is an increasing need for primary care doctors to look after these patients although whether family doctors are adequately trained and prepared is unknown.

Objective

This study aimed to determine if doctors with family medicine (FM) training are associated with enhanced empathy in consultation and enablement for patients with chronic illness as compared to doctors with internal medicine training or without any postgraduate training in different clinic settings.

Methods

This was a cross-sectional questionnaire survey using the validated Chinese version of the Consultation and Relational Empathy (CARE) Measure as well as Patient Enablement Instrument (PEI) for evaluation of quality and outcome of care. 14 doctors from hospital specialist clinics (7 with family medicine training, and 7 with internal medicine training) and 13 doctors from primary care clinics (7 with family medicine training, and 6 without specialist training) were recruited. In total, they consulted 823 patients with chronic illness. The CARE Measure and PEI scores were compared amongst doctors in these clinics with different training background: family medicine training, internal medicine training and those without specialist training. Generalized estimation equation (GEE) was used to account for cluster effects of patients nested with doctors.

Results

Within similar clinic settings, FM trained doctors had higher CARE score than doctors with no FM training. In hospital clinics, the difference of the mean CARE score for doctors who had family medicine training (39.2, SD = 7.04) and internal medicine training (35.5, SD = 8.92) was statistically significant after adjusting for consultation time and gender of the patient. In the community care clinics, the mean CARE score for doctors with family medicine training and those without specialist training were 32.1 (SD = 7.95) and 29.2 (SD = 7.43) respectively, but the difference was not found to be significant. For PEI, patients receiving care from doctors in the hospital clinics scored significantly higher than those in the community clinics, but there was no significant difference in PEI between patients receiving care from doctors with different training backgrounds within similar clinic setting.

Conclusion

Family medicine training was associated with higher patient perceived empathy for chronic illness patients in the hospital clinics. Patient enablement appeared to be associated with clinic settings but not doctors’ training background. Training in family medicine and a clinic environment that enables more patient doctor time might help in enhancing doctors’ empathy and enablement for chronic illness patients.     

Sleep,daily activity rhythms and postpartum mood: A longitudinal study across the perinatal period

Women with a diagnosis of bipolar and major depressive disorders are at higher risk to develop postpartum depression. The primary objective of this longitudinal study was to determine whether daily activity rhythms and sleep parameters differ between women with and without a history of a mood disorder across the perinatal period. A secondary objective was to determine whether changes in these parameters were associated with postpartum mood. In total, 33 women were included in this study, 15 of which had a history of a mood disorder (high-risk group) and 18 who did not (low-risk group). Sleep and daily rhythms were assessed subjectively and objectively during the third trimester (≥26 weeks gestation) and again at 6–12 weeks postpartum. Mood was also assessed at both time points. Women in the high-risk group showed greater subjective daily rhythms and sleep disturbances across the perinatal period. Objective sleep efficiency was worse in the high-risk group in the postpartum period. Changes in both subjective daily rhythms and objective sleep efficiency were predictive of changes in depressive symptoms across the perinatal period. These findings encourage the development of preventative therapeutics to ensure circadian rhythm and sleep stability throughout the perinatal period.     

Psychiatric consequences of road traffic accidents.

OBJECTIVE--To determine the psychiatric consequences of being a road traffic accident victim. DESIGN--Follow up study of road accident victims for up to one year. SETTING--Emergency department of the John Radcliffe Hospital, Oxford. SUBJECTS--188 consecutive road accident victims aged 18-70 with multiple injuries (motorcycle or car) or whiplash neck injury, who had not been unconscious for more than 15 minutes, and who lived in the catchment area. MAIN OUTCOME MEASURES--Present state examination "caseness"; post-traumatic stress disorder and travel anxiety; effects on driving and on being a passenger. RESULTS--Acute, moderately severe emotional distress was common. Almost one fifth of subjects, however, suffered from an acute stress syndrome characterised by mood disturbance and horrific memories of the accident. Anxiety and depression usually improved over the 12 months, though one tenth of patients had mood disorders at one year. In addition, specific post-traumatic symptoms were common. Post-traumatic stress disorder occurred during follow up in one tenth of patients, and phobic travel anxiety as a driver or passenger was more common and frequently disabling. Emotional disorder was associated with having pre-accident psychological or social problems and, in patients with multiple injuries, continuing medical complications. Post-traumatic syndromes were not associated with a neurotic predisposition but were strongly associated with horrific memories of the accident. They did not occur in subjects who had been briefly unconscious and were amnesic for the accident. Mental state at three months was highly predictive of mental state at one year. CONCLUSIONS--Psychiatric symptoms and disorder are frequent after major and less severe road accident injury. Post-traumatic symptoms are common and disabling. Early information and advice might reduce psychological distress and travel anxiety and contribute to road safety and assessing "nervous shock."     

DEPRESSED MOOD IN THE WORKING POPULATION: ASSOCIATIONS WITH WORK SCHEDULES AND WORKING HOURS

The impact of working time arrangements (WTA) on health has been studied extensively. Still, little is known about the interrelation between work schedules, working hours, and depressed mood. For work schedules, the underlying assumptions regarding depressed mood refer to a disturbance of social and biological rhythms, whereas for working hours, the assumptions relate to workload and work capacity. Conversely, depressed mood may urge an employee to adjust his/her work schedule and/or number of working hours/week (h/wk). The aim of this study was to assess the association between work schedule and working hours with depressed mood. Using baseline data from the Maastricht Cohort Study, depressed mood in day work was compared with depressed mood in different shiftwork schedules (n?=?8843). Within day work, several categories of working h/wk were studied in association with depressed mood (n?=?7217). The association between depressed mood and several aspects of overtime was assessed separately. Depressed mood was measured with a dichotomous item: “Did you feel down every day over the last two weeks?” Separate logistic regression analyses were conducted for men and women, with adjustments for potential confounders. The odds ratio (OR) for depressed mood was greater for men involved in shiftwork than for men only involved in day work (three-shift OR?=?2.05 [95% confidence interval, CI 1.52–2.77]; five-shift OR?=?1.34 [95% CI 1.00–1.80]; irregular-shift OR?=?1.79 [95% CI 1.27–2.53]). In female employees, five-shift work was associated with a higher prevalence of depressed mood (OR?=?5.96 [95% CI 2.83–12.56]). Regarding the number of working h/wk, men working <26?h/wk had a higher prevalence of depressed mood than men working 36–40?h/wk (OR?=?2.73 [95% CI 1.35–5.52]). After conducting trend analyses, a significant decreasing trend was found in men, whereas an increasing trend was found in women working a high number of hours. Furthermore, a dose-response relationship was present in men regarding the number of overtime h/wk. This study showed that different work schedules and working hours are associated with depressed mood. Shiftwork was related to a higher prevalence of depressed mood than day work. The association was more pronounced for male employees. Regarding the number of working h/wk, male and female employees showed an opposite trend in depressed mood. Because of the possibility of a healthy worker effect and the possibility of a reciprocal relationship between WTA and depressed mood, the reported relation might be underestimated. This study has illustrated that occupational physicians, who deal with depressed mood among workers, should carefully consider the impact of WTA. (Author coorespondence: Karolien.Driesen@epid.unimaas.nl)     

Prenatal exposure to maternal depression,neonatal methylation of human glucocorticoid receptor gene (NR3C1) and infant cortisol stress responses

Background: In animal models, variations in early maternal care are associated with differences in hypothalamic-pituitary-adrenal (HPA) stress response in the offspring, mediated via changes in the epigenetic regulation of glucocorticoid receptor (GR) gene (Nr3c1) expression. Objective: To study this in humans, relationships between prenatal exposure to maternal mood and the methylation status of a CpG-rich region in the promoter and exon 1F of the human GR gene (NR3C1) in newborns and HPA stress reactivity at age 3 months were examined. Methods: The methylation status of a CpG-rich region of the NR3C1 gene, including exon 1F, in genomic DNA from cord blood mononuclear cells was quantified by bisulfite pyrosequencing in infants of depressed mothers treated with a serotonin reuptake inhibitor antidepressant (SRI) (n=33), infants of depressed non treated mothers (n=13) and infants of non depressed/non treated mothers (n=36). To study the functional implications of the newborn methylation status of NR3C1 in newborns, HPA function was assessed at 3 months using salivary cortisol obtained before and following a non noxious stressor and at a late afternoon basal time. Results: Prenatal exposure to increased third trimester maternal depressed/anxious mood was associated with increased methylation of NR3C1 at a predicted NGFI-A binding site. Increased NR3C1 methylation at this site was also associated with increased salivary cortisol stress responses at 3 months, controlling for prenatal SRI exposure, postnatal age, and pre and postnatal maternal mood. Conclusions: Methylation status of the human NR3C1 gene in newborns is sensitive to prenatal maternal mood and may offer a potential epigenetic process that links antenatal maternal mood and altered HPA stress reactivity during infancy.     

Negative Mood and Alcohol Problems are Related to Respiratory Dynamics in Young Adults

This study examined the relationship of negative affect and alcohol use behaviors to baseline respiration and respiratory response to emotional challenge in young adults (N = 138, 48 % women). Thoracic-to-abdominal ratio, respiratory frequency and variability, and minute volume ventilation were measured during a low-demand baseline task, and emotional challenge (viewing emotionally-valenced, emotionally-neutral, and alcohol-related pictures). Negative mood and alcohol problems principal components were generated from self-report measures of negative affect and mood, alcohol use, and use-related problems. The negative mood component was positively related to a thoracic bias when measured throughout the study (including baseline and picture exposure). There was generally greater respiratory activity in response to the picture cues, although not specifically in response to the content (emotional or alcohol-related) of the picture cues. The alcohol problems component was positively associated with respiratory reactivity to picture cues, when baseline breathing patterns were controlled. Self-report arousal data indicated that higher levels of negative mood, but not alcohol problems, were associated with greater arousal ratings overall. However, those with alcohol problems reported greater arousal to alcohol cues, compared to emotionally neutral cues. These results are consistent with theories relating negative affect and mood to breathing patterns as well as the relationship between alcohol problems and negative emotions, suggesting that the use of respiratory interventions may hold promise for treating problems involving negative affect and mood, as well as drinking problems.     

Seasonality in mood and behaviours of Japanese residents in high-latitude regions: transnational cross-sectional study

Background

Daylight hours in high-latitude regions tend to be longer than those in Japan in summer, and shorter than those in Japan in winter. For example, daylight hours in London in winter are one-third those of Tokyo. Therefore, this study investigated and compared seasonal changes in mood and behaviours of Japanese individuals living in and outside Japan.

Methods

Surveys were conducted with Japanese residents in summer and winter in the UK (n?=?106), Nordic countries (n?=?40), Southeast Asia (n?=?50), and Japan (n?=?96). First, summer and winter General Health Questionnaire–28 (GHQ28) scores of each regional group were analysed. Subsequently, month-wise differences in mood and behaviours were compared across the four geographical regions.

Results

Summer and winter GHQ28 scores of participants living in the UK and Nordic countries differed significantly, while no seasonal differences were observed for residents in Japan and Southeast Asia. Further, in the UK and Nordic countries, summer was associated with better mood and more activity, while winter was linked to lowered mood and reduced activity.

Conclusion

The results indicate that Japanese living in the UK and Nordic countries (high-latitude regions) experience seasonal fluctuations in depressive symptoms that may be linked to drastic seasonal environmental changes. Observed over a 12-month period, their mood and behaviour declined in winter and improved in summer. Therefore, considering the prevalence of overseas stressors that differ from those in their home country, it is necessary to investigate the effectiveness of support systems that help migrants adapt to seasonal changes in high-latitude regions.

     

WORK HOURS AND SLEEP/WAKE BEHAVIOR OF AUSTRALIAN HOSPITAL DOCTORS

The objective of the study was to describe the work and sleep patterns of doctors working in Australian hospitals. Specifically, the aim was to examine the influence of work-related factors, such as hospital type, seniority, and specialty on work hours and their impact on sleep. A total of 635 work periods from 78 doctors were analyzed together with associated sleep history. Work and sleep diary information was validated against an objective measure of sleep/wake activity to provide the first comprehensive database linking work and sleep for individual hospital doctors in Australia. Doctors in large and small facilities had fewer days without work than those doctors working in medium-sized facilities. There were no significant differences in the total hours worked across these three categories of seniority; however, mid-career and senior doctors worked more overnight and weekend on-call periods than junior doctors. With respect to sleep, although higher work hours were related to less sleep, short sleeps (< 5 h in the 24 h prior to starting work) were observed at all levels of prior work history (including no work). In this population of Australian hospital doctors, total hours worked do impact sleep, but the pattern of work, together with other nonwork factors are also important mediators. (Author correspondence: sally.ferguson@unisa.edu.au)     

Experimental mood manipulation does not induce change in preference for natural landscapes

According to evolutionary theory, emotions are psychological mechanisms that have evolved to enhance fitness in specific situations by motivating appropriate (adaptive) behavior. Taking this perspective, a previous study examined the relationship between mood and preference for natural environments. It reported that participants’ anxiety level was associated with a preference for landscapes offering what Appleton called "refuge," while participants’ anger and cheerfulness were both associated with a preference for landscapes offering what Appleton called "prospect." We attempted to replicate these results and to improve on the study by experimentally manipulating mood. Using a between-subjects design, 80 participants were instructed to self-induce one of four moods: anger, sadness, anxiety, or joy. After the mood induction, they viewed fourteen landscape photographs and recorded the seven most preferred. It was hypothesized that subjects experiencing anger or joy would prefer landscapes rich in "prospect" features, whereas participants experiencing sadness or anxiety would prefer landscapes rich in "refuge" features. In contrast to the previous study, the predictions were not supported: artificially induced moods may not provide ecological validity as a test of the "mood as motivator" model; alternatively, the first study may have reported an alpha error. To see whether the model has practical value, we recommend a study of landscape preference using participants with clinically significant levels of mood dysphoria. Bernadette Klopp received her B.A. (Honours) in Psychology from the University of Queensland. Her areas of research interest focus on environment and aesthetics, environmental psychology, and the evolution of art as a form of social communication. Bernadette is currently employed by the Commonwealth Rehabilitation Service of Queensland, but she hopes to pursue further graduate study. Linda Mealey, Ph.D., is just finishing a three-year stint as Senior Lecturer at the School of Psychology, University of Queensland, before returning to her Associate Professor position at the College of St. Benedict in central Minnesota. She is Vice-President/President-Elect of the International Society for Human Ethology, a Councilor of the Human Behavior and Evolution Society, and a member of the editorial board of Politics and the Life Sciences.     

The Relationship of Dream Content and Changes in Daytime Mood in Traumatized vs. Non-Traumatized Children

The study examined how the mood changes from night to morning, and how dysphoric dream contents associate with this change among children who live in traumatic environment and their controls from peaceful area. The sample consisted of 413 Palestinian boys and girls of 6–15 years of age, the mean age being 11.22 ± 2.64. The participants filled in a seven-day dream diary in which they recorded their recalled dreams every morning. First, the results, confirmed that mood change from evening to morning is a general dream function: age and gender are not related to the change. The mood chance was rather associated with what and whom the children dreamt about. Second, the hypothesis of the trauma group showing less change in dysphoric dream content and in the intensity of negative morning mood across a period of time of seven days was not confirmed. On the contrary, the results showed that both dreams incorporating dysphoric themes and negative morning mood decreased only among children living in traumatic conditions. Third, it was hypothesized that there is a stronger association between presleep negative mood and dysphoric dreams, as well as between the dysphoric dreams and negative morning mood among children living in traumatic environment than among children from peaceful area. Contrary to the hypothesis, results for the trauma group revealed a reverse association between evening mood and dream contents: the more afraid, angry and worried children felt in the evening, the more Happy recreation dreams they reported, and the happier evening mood they reported, the more Threatening stranger dreams they had. However, concurring with the hypothesis, a direct association was found between dysphoric dreams and negative morning mood in the trauma group. The more children dreamt about Threatening strangers, the more afraid, angry and worried they felt in the morning. The discussion proposes a model of the correcting or balancing dream function that is characterized by an reverse assimilation of incorporating evening mood into dreams, and by a direct accommodation of dream content into morning mood.     

Increased depressive-like traits in an animal model of premenstrual irritability

Women are at higher risk of anxiety and mood disorders, especially at transitions across the reproductive life cycle (premenstruum, postpartum, menopause). Premenstrual dysphoric disorder (PMDD) is one of female mood disorders associated with changing ovarian hormone levels. Because anxiety and depression frequently occur in women with PMDD, premenstrual dysphoria might be a manifestation of certain vulnerability traits increasing the risk of those disorders. The present study was conducted to elucidate a potential association between estrous cycle-dependent aggression, the rodent model of "premenstrual irritability" (resident-intruder test), and anxiety (elevated plus maze), depressive-like traits (forced swim test) as well as carbohydrate craving in female Wistar rats. Some aggressive and nonaggressive females were restraint-stressed before testing to determine their sensitivity to stress at different hormonal stages. The results revealed that females expressing the estrous cycle-dependent aggression but not those not expressing cycle-dependent aggression spent longer time immobile and shorter time swimming in the forced swim test at metestrus compared to proestrus phase of the estrous cycle. There was no difference between aggressive and nonaggressive females in anxiety, locomotor activity and sensitivity to restraint stress and sucrose consumption. The present study suggests a common neurobiological background for the estrous cycle-dependent aggression and depressive-like traits in rodents. This phenomenon could potentially aid the elucidation of premenstrual emotional dysfunctions and might be used as an ethological model to study a biochemical and genetic proneness to depression.     

Wise “birds” follow their clock: The role of emotional intelligence and morningness–eveningness in diurnal regulation of mood

Emotional intelligence (EI) and morningness–eveningness (M-E) preference have been shown to influence mood states. The present article investigates the way in which these two constructs may interact, influencing morning and evening mood levels. A sample of 172 participants completed a multidimensional mood scale measuring energetic arousal (EA), tense arousal (TA), and hedonic tone at 7:00 and at 22:00. As expected, morning and evening types experienced higher EA at their preferred time of day; effects of M-E on other mood dimensions were weaker. EI was found to correlate with lower TA, but the association was stronger at 22:00, perhaps reflecting the role of EI in managing the social events characteristic for the evening hours. An interactive effect of EI and M-E was found for both diurnal changes and morning levels of EA. Namely, in individuals higher in EI, there appeared a more marked synchrony effect between chronotype and EA, which was absent in those low in EI; individuals higher in EI showed more pronounced diurnal changes in EA characteristic for their chronotype (i.e., higher EA at morning hours in morning chronotypes; higher EA at evening hours in evening chronotypes), while in participants low in EI, diurnal changes in EA were smaller. Moreover, the characteristic positive association between morningness and EA during morning hours was apparent only in those high in EI. These findings suggest that individual differences in circadian variation in mood reflect several factors, including an endogenous rhythm in energy, the distribution of social activities throughout the day, and the person’s awareness of their own energy level.