Personality Correlates with Sleep‐Wake Variables

The role of objectively recorded smartphone usage and personality traits in sleep quality

Purpose

The proliferation of smartphones, accompanied by internet facilities, has contributed to a decrease in sleep quality over the last decades. It has been revealed that excessive internet usage impacts the physical and mental health of smartphone users, while personality traits (PT) could play a role in developing internet addictions and preventing their negative effects. The objective of the present study is to assess the role of PT and smartphone usage in sleep quality.

Method

The sample comprised 269 participants, 55% females, within the age range of 15-64 years. We objectively collected one-week smartphone apps usage data from the participants. They also responded to demographics and the PT (BFI-10) questionnaires. The usage data of smartphone apps were processed to calculate smartphone usage amounts and sleep variables, including sleep duration, sleep distraction, sleeping time, and wake-up time. The data were analyzed using the correlation coefficient and regression analyses.

Results

The results indicated that more smartphone usage was associated with reduced sleep duration, increased sleep distraction, and later bedtime. Furthermore, smartphone users with the conscientiousness trait had a longer sleep duration, earlier sleeping time, less sleep distraction, and earlier wakeablity. Sleep distraction was positively associated with openness. Extraversion and neuroticism were found to be positive predictors of early wakeablity. Neuroticism had a negative association with early wakeablity. Finally, the implications of the study have been discussed.

Conclusion

Our study's usage of data that was acquired objectively has strong methodological qualities. The present study is the first to contribute to the literature on the role of PT and objectively measured smartphone usage in the prediction of sleep quality. We found that smartphone use and sleep variables are associated with PT. Other scholars can use our dataset for benchmarking and future comparisons.

The Relationship of Neuroticism with Sleep Quality: The Mediating Role of Emotional, Cognitive and Metacognitive Factors

BACKGROUND

Poor sleep quality is associated with a broad range of psychopathology and is a common problem among college students. This study aimed to investigate the mediating role of metacognitive beliefs related to sleep, emotion regulation and a negative cognitive style related to anxiety (looming cognitive style) in the relation between neuroticism and reported sleep quality.

PARTICIPANTS

Participants were 343 undergraduates from three universities in Tehran (56.3% females, Mean age = 22.01 ± 2.74 years).

METHOD

Data were gathered with a questionnaire packet that included the Pittsburgh Sleep Quality Index (PSQI), Metacognitions Questionnaire-Insomnia (MCQ-I), Emotion Regulation Questionnaire (ERQ), Looming Maladaptive Style Questionnaire (LMSQ) and Neuroticism subscale of NEO-PI-R.

RESULTS

Structural equation modeling analyses supported a proposed model (R² = 37%) which proposed that neuroticism both directly and indirectly linked to reported sleep quality through metacognitions related to sleep, cognitive reappraisal and looming cognitive style (χ2 = 1194.87, p < .001; CFI = 0.93, NFI = 0.90, RMSEA = 0.065, GFI = 0.92, SRMR = 0.069, IFI = 0.93).

CONCLUSIONS

The results provide evidence for the impact of neuroticism on reported sleep quality through metacognitive, cognitive and emotional factors. The result suggest that special attention should be paid to these factors in the treatment and psychopathology of sleep quality.

The impact of social networks on sleep among a cohort of college students

Background

Sleep duration and quality are associated with physical and mental wellbeing. This paper examines social network effects on individual level change in the sleep quantity and quality from late adolescence to emerging adulthood and its associated factors, including the influence of peers on sleep behavior and the impact of changes in network size.

Methods

We use sleep data from 619 undergraduates at the University of Notre Dame obtained via Fitbit devices as part of the NetHealth project. The data were collected between August 16, 2015 and May 13, 2017. We model trends in sleep behaviors using latent growth-curve models.

Results

Controlling for the many factors known to impact sleep quantity and quality, we find two social network effects: increasing network size is associated with less sleep and a student's sleep levels are influenced by his or her peers. While we do not find any consistent decline in sleep quantity over the 637 days, daily fluctuations in sleep quantity are associated with changes in network size and the composition of a student's network. As a student's network gets bigger, s/he sleeps less, and when a student's contacts sleep more (or less) than s/he does, the student becomes more like his or her contacts and sleeps more (or less).

Conclusions

Social networks can and do impact sleep, especially sleep quantity. In contexts where students want to have larger networks, the difficulties of increasing network size and maintaining larger networks negatively impact sleep. Because of peer influence, the effectiveness of interventions designed to improve sleep practices could be increased by leveraging student social networks to help diffuse better sleep habits.

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The sleep habits of 619 undergraduates were traced with Fitbit devices for 637 days.

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Their sleep quantity measures were relatively stable but affect by peers.

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Their sleep quality was slightly getting worse but not affected by peers.

Association of P10L Polymorphism in Melanopsin Gene with Chronic Insomnia in Mexicans

The aim of this pilot study was to determine the association of the P10L (rs2675703) polymorphism of the OPN4 gene with chronic insomnia in uncertain etiology in a Mexican population. A case control study was performed including 98 healthy subjects and 29 individuals with chronic insomnia not related to mental disorders, medical condition, medication or substance abuse. Samples were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Genetic analyses showed that the T allele of P10L increased risk to chronic insomnia in a dominant model (p = 1 ×10⁻⁴; odds ratio (OR) = 9.37, CI = 8.18–335.66, Kelsey statistical power (KSP) = 99.9%), and in a recessive model (p = 7.5 × 10⁻⁵, OR = 9.37, KSP = 99.3%, CI = 2.7–34.29). In the insomnia group, we did not find a correlation between genotypes and chronotype (p = 0.219 Fisher’s exact test), severity of chronic insomnia using ISI score (p = 0.082 Fisher’s exact test) and ESS score (p ˃ 0.999 Fisher’s exact test). However, evening chronotype was correlated to daytime sleepiness severity, individuals with an eveningness chronotype had more severe drowsiness according to their insomnia severity index (ISI) score (p = 0.021 Fisher’s exact test) and Epworth sleepiness scale (ESS) score (p = 0.015 Fisher’s exact test) than the morningness and intermediate chronotype. We demonstrated that the T allele of the P10L polymorphism in the OPN4 gene is associated with chronic insomnia in Mexicans. We suggest the need to conduct larger studies in different ethnic populations to test the probable association and function of P10L and other SNPs in the OPN4 gene and in the onset of chronic insomnia.

Morningness-eveningness preference and sensation seeking

The aim of this study was to explore the relationship between circadian preference and sensation seeking. To this aim 1041 university students (408 males and 633 females), ranging in age between 18 and 30 years, filled the reduced version of the Morningness-Eveningness Questionnaire (MEQr) and the Sensation Seeking Scale-Form V (SSS-V). Males scored higher than females in SSS-V total score and all subscales, except experience seeking (ES). As regards circadian preference, evening types scored higher than morning types in SSS-V total score and all subscales, except boredom susceptibility (BS) where they significantly differed only from intermediate types. On the whole our results highlight a significant relationship between circadian preference and sensation seeking.

[Anxiety, sleep self-assessment, cortisol and saliva antioxidants in students with occasional experience of shift work]

AIM

To study the anxiety level, sleep self-assessment and indicators of morning and evening levels of cortisol and saliva antioxidants in students with experience of occasional shift work.

MATERIAL AND METHODS

University students (n=159) with experience of shift work were examined. Psychoemotional status was assessed using the Eysenck personality questionnaire (EPQ), Spielberger-Khanin anxiety inventory, The Taylor Manifest Anxiety Scale (Nemchin's modification). The express-questionnaire The Quality of Sleep Hygiene, the Sleep Quality scale and the scale of drowsiness were used to assess sleep. Saliva morning and evening cortisol levels (ELISA) and the total antioxidant activity (amperometric method) were determined.

RESULTS AND CONCLUSION

There was an increase in the number of respondents with higher anxiety, higher scores of psychoticism and neuroticism. According to the self-assessment of sleep, a statistically significant decrease in the quality of sleep hygiene was shown. Biochemical parameters of the saliva differed significantly only in the morning hours: the increase in cortisol and decrease in the antioxidant activity were observed. The results suggest the possibility of asymptomatic development of emotional disorders and metabolic disorders in people with occasional night shift work.

Insomnia as a Partial Mediator of the Relationship Between Personality and Future Symptoms of Anxiety and Depression Among Nurses

Background: This study investigates insomnia as a partial mediator in the relationship between personality and symptoms of anxiety and depression.

Methods: The study is based on partly longitudinal data from the ongoing cohort study “Survey of Shift work, Sleep, and Health” (SUSSH) among Norwegian nurses, a survey examining the work situation and health status of Norwegian nurses measured with annual questionnaires. The present study uses data collected in 2012 (Wave 4), 2013 (Wave 5), and 2014 (Wave 6). The final sample at Wave 6 consisted of 2002 participants, of which 91% were females. The questionnaires included items measuring, among others, demographic variables, work time schedule, insomnia (Bergen Insomnia Scale), personality (Mini-IPIP) and anxiety and depression (Hospital Anxiety and Depression Scale).

Results: Extraversion and conscientiousness had no significant direct or indirect association with insomnia, anxiety or depression. Neuroticism and insomnia had direct associations to future symptoms of anxiety and depression. Insomnia was also a significant partial mediator of the relationship between both neuroticism and anxiety, and neuroticism and depression, meaning that neuroticism had an indirect relation to symptoms of anxiety and depression through insomnia. When adjusting for previous symptoms of anxiety and depression at Wave 5, insomnia was no longer a significant mediator between neuroticism and anxiety, and only marginally mediated the relationship between neuroticism and depression.

Conclusion: The results showed that insomnia may act as a mediator between neuroticism and symptoms of anxiety and depression, but the indirect relationship between neuroticism and anxiety and depression through insomnia is considerably weaker than the direct association. Hence, the mediating effect of insomnia should be interpreted with caution. The sample mainly consisted of female nurses, and the generalizability of the findings to male dominated occupations is limited. Findings from the present study highlight the importance of an integrated approach and strengthen the understanding of how personality and psychopathology are connected.

The relationship between the development of social competence and sleep in infants: a longitudinal study

BACKGROUND

Many reports argue that sleep is important for children's health, learning, and academic performance. The purpose of this longitudinal study was to examine the association between sleep and the development of social competence in infants.

METHODS

This study was conducted as part of a Japan Science and Technology Agency (JST) project. Caregivers responded to the Japan Children's Study Sleep Questionnaire when children were 18 months old. The interactions of caregivers and children were observed when children were 18, 30, and 42 months old, and rated with the Interaction Rating Scale, which is a measure of social competence.

RESULTS

Nocturnal sleep duration of more than 10 h and an earlier bed time than 22:00 were significantly correlated with two trajectory groups (low point and high point transition groups) of children's social competence at 18, 30, and 42 months. Further, total sleep duration of more than 12.25 h and an earlier bed time than 22:00 were significantly correlated with the trajectory of children's social competence at 18, 30, and 42 months.

CONCLUSIONS

Sleep duration and sleep onset time are important factors in children's development of social competence.Trial registration The ethics committee of the JST approved this study on March 19, 2001. The registration number is 356-1.

Recognizing Academic Performance, Sleep Quality, Stress Level, and Mental Health using Personality Traits, Wearable Sensors and Mobile Phones

What can wearable sensors and usage of smart phones tell us about academic performance, self-reported sleep quality, stress and mental health condition? To answer this question, we collected extensive subjective and objective data using mobile phones, surveys, and wearable sensors worn day and night from 66 participants, for 30 days each, totaling 1,980 days of data. We analyzed daily and monthly behavioral and physiological patterns and identified factors that affect academic performance (GPA), Pittsburg Sleep Quality Index (PSQI) score, perceived stress scale (PSS), and mental health composite score (MCS) from SF-12, using these month-long data. We also examined how accurately the collected data classified the participants into groups of high/low GPA, good/poor sleep quality, high/low self-reported stress, high/low MCS using feature selection and machine learning techniques. We found associations among PSQI, PSS, MCS, and GPA and personality types. Classification accuracies using the objective data from wearable sensors and mobile phones ranged from 67-92%.

A longitudinal examination of the bidirectional association between sleep problems and social ties at university: the mediating role of emotion regulation

Despite the growing body of research linking sleep problems and social ties, research investigating the direction of effects between these two constructs is lacking. Furthermore, there remains a dearth of research examining the mechanisms that may explain the association between sleep problems and social ties within a longitudinal design. The present 3-year longitudinal study addressed two research questions: (1) Is there a bidirectional association between sleep problems and social ties at university? and (2) Does emotion regulation mediate the association between sleep problems and social ties at university? Participants (N = 942, 71.5% female; M = 19.01 years at Time 1, SD = 0.90) were university students who completed annual assessments of sleep problems, social ties, and emotion regulation, for three consecutive years. Results of path analysis indicated that the bidirectional association between sleep problems and social ties was statistically significant (controlling for demographics, sleep-wake inconsistency, sleep duration, and alcohol). Analyses of indirect effects indicated that emotion regulation mediated this link, such that better sleep quality (i.e., less sleep problems) led to more effective emotion regulation, which, subsequently, led to more positive social ties. In addition, more positive social ties led to more effective emotion regulation, which, in turn, led to less sleep problems. The findings highlight the critical role that emotional regulation plays in the link between sleep problems and social ties, and emphasize the need for students as well as university administration to pay close attention to both the sleep and social environment of university students.

Chronotype, bed timing and total sleep time in seniors

Many older adults (seniors) experience problems with getting enough sleep. Because of the link between sleep and circadian rhythms, changes in bedtime lead to changes in the amount of sleep obtained. Although primarily determined genetically, chronotype changes with advancing age towards a more morning-type (M-type) orientation. In a 2006 study, we have found a linear relationship, by which the earlier a senior's bedtime, the more sleep she/he will obtain. The aim of this study was to see whether this relationship differs for M-type seniors, as compared to seniors outside the M-type category. Retired seniors (n = 954, 535 M, 410F, 65 years+, mean age 74.4 years) taking part in a telephone interview were divided into M-types and Other types (O-types) using the Composite Scale of Morningness (CSM). The relationship between bedtime and Total Sleep Time (TST), and between rise-time and TST, was tested using linear regression separately for M-types and O-types. For each participant, habitual bedtime, rise-time and total Sleep Time (TST) [after removing time spent in unwanted wakefulness] were obtained using a telephone version of the Sleep Timing Questionnaire (STQ). Both chronotype groups showed a significant linear relationship between bedtime and TST (p < 0.001); with earlier bedtimes leading to more TST (M-type 5.6 min; O-type 4.4 min per 10 min change [slope difference p = 0.05]); and an opposite relationship between rise-time and TST with earlier rise-times leading to less TST (M-type 6.7 min; O-type 4.2 min per 10 min change [slope difference p = 0.001]). M-types retired to bed 56 min earlier (p < 0.001), awoke 93 min earlier (p < 0.001) and obtained 23 min less TST (p < 0.001) than O-types. In conclusion, both chronotypes showed TST to be related in a linear way to bedtime and rise-time; the overall shorter TST in M-types was due to them rising 93 min earlier, but only retiring to bed 56 min earlier than O-types; as well as having a steeper rise-time versus TST relationship.

Maintaining sleep and physical activity alleviate mood instability

OBJECTIVE

Building on previous work indicating that mood instability is the hallmark of neuroticism, our aim was to examine whether changes in exercise, sleep duration and leisure predicted decreases in mood instability with time.

METHODS

We used data from 3374 participants of the British Health and Lifestyle Study who answered the Eysenck Personality Inventory-Neuroticism subscale (EPI-N) and the General Health Questionnaire on two occasions 7 years apart. We predicted mood instability scores derived from the EPI-N at follow-up using self-reported changes in exercise, sleep duration and leisure hours between the two time points as independent variables.

RESULTS

We confirmed the observation that mood instability decreases with age. Maintaining one's exercise at baseline level decreased mood instability (beta=-0.21) while sleeping less increased mood instability (beta=0.14). Change in leisure time was not independently related to mood instability after accounting for the two other lifestyle factors.

CONCLUSION

Personality, at least with regard to mood instability, can be modified by lifestyle factors. Exercise and sleep support mood stability and could be important components of preventative mental health (as well as physical health) benefits.

Associations between morningness/eveningness and psychopathology: an epidemiological survey in three in-patient psychiatric clinics

OBJECTIVE

This study aims to examine the association between the chronotype (morningness/eveningness) and specific mental disorders.

METHODS

Cross-sectional epidemiological study conducted in three in-patient clinical settings. A total of 1468 consecutive in-patients who gave their written consent were enrolled. On the admission day, patients filled sleep questionnaires and a nurse filled a Clinical Global Impressions scale. Hospitalization reports and ICD-10 diagnoses were collected.

RESULTS

Sleep/wake schedule was similar between the psychiatric diagnoses. On the other hand, morning type patients had an earlier bedtime, earlier wakeup time and shorter sleep duration than the other chronotype regardless of the diagnosis. In multivariate models, patients with a depressive disorder or a psychosis were more likely to be morning type. Patients with an anxiety disorder, addiction disorder or personality disorder were more likely to be evening type.

CONCLUSIONS

Age and sleep/wake schedule are contributing factors for the chronotype but mental disorders too appeared to modulate chronotype preferences.

A study on the sleep quality of incoming university students

This study was designed to examine the prevalence and the risk factors of poor sleep quality in 4318 incoming university students in Taiwan. The test battery comprised a self-administered structured questionnaire, including items related to personal medical history and lifestyle habits, the Measurement of Support Functions (MSF), Pittsburgh Sleep Quality Index (PSQI), Chinese Internet Addiction Scale-Revision (CIAS-R), neuroticism subscale of the Maudsley Personality Inventory (MPI), and the 12-item Chinese Health Questionnaire (CHQ-12). Of the total study population, 2360 students (54.7%) were classified into the poor sleep quality group, as defined by a PSQI score ≥6. Based on the results of multivariate logistic regression analysis, poor sleep quality was significantly associated with undergraduate students, female gender, skipping breakfast, tea drinking, a higher tendency toward internet addition, poor social support, higher neuroticism, and higher CHQ scores. Poor sleep quality is prevalent among incoming university students in Taiwan, and more work is needed on the identification of the factors influencing poor sleep, and in providing systematic education in the importance of sleep and time management skills to university students.

Chronotype and diurnal patterns of positive affect and affective neural circuitry in primary insomnia

While insomnia is a well-established risk factor for the initial onset, recurrence or relapse of affective disorders, the specific characteristics of insomnia that confer risk remain unclear. Patients with insomnia with an evening chronotype may be one particularly high-risk group, perhaps due to alterations in positive affect and its related affective circuitry. We explored this possibility by comparing diurnal patterns of positive affect and the activity of positive affect-related brain regions in morning- and evening-types with insomnia. We assessed diurnal variation in brain activity via the relative regional cerebral metabolic rate of glucose uptake by using [(18) F]fluorodeoxyglucose-positron emission tomography during morning and evening wakefulness. We focused on regions in the medial prefrontal cortex and striatum, which have been consistently linked with positive affect and reward processing. As predicted, chronotypes differed in their daily patterns in both self-reported positive affect and associated brain regions. Evening-types displayed diurnal patterns of positive affect characterized by phase delay and smaller amplitude compared with those of morning-types with insomnia. In parallel, evening-types showed a reduced degree of diurnal variation in the metabolism of both the medial prefrontal cortex and the striatum, as well as lower overall metabolism in these regions across both morning and evening wakefulness. Taken together, these preliminary findings suggest that alterations in the diurnal activity of positive affect-related neural structures may underlie differences in the phase and amplitude of self-reported positive affect between morning and evening chronotypes, and may constitute one mechanism for increased risk of mood disorders among evening-type insomniacs.

Happy as a lark: morning-type younger and older adults are higher in positive affect

A literature on young adults reports that morning-type individuals, or "larks," report higher levels of positive affect compared with evening-type individuals, or "owls" (Clark, Watson, & Leeka, 1989; Hasler et al., 2010). Morning types are relatively rare among young adults but frequent among older adults (May & Hasher, 1998; Mecacci et al., 1986), and here we report on the association between chronotype and affect in a large sample of healthy younger and older adults. Overall, older adults reported higher levels of positive affect than younger adults, with both younger and older morning types reporting higher levels of positive affect and subjective health than age mates who scored lower on morningness. Morningness partially mediated the association between age and positive affect, suggesting that greater morningness tendencies among older adults may contribute to their improved well-being relative to younger adults.

Neuroticism and extraversion personality traits, health behaviours, and subjective well-being: the Fukuoka Study (Japan)

PURPOSE

We evaluated personality dimensions captured by an abbreviated 8-item questionnaire and examined associations of the personality traits with health behaviours and subjective well-being (SWB) measures.

METHODS

The subjects were 11,554 participants in the Kyushu University Fukuoka Cohort Study who completed a self-administered questionnaire inquiring health behaviours, morbidity, personality, and SWB. Personality was assessed by using a questionnaire appeared to capture neuroticism and extraversion traits, and SWB-related variables were assessed with 3 single-item questions.

RESULTS

Neuroticism was negatively and extraversion was positively associated with BMI. Extraversion, but not neuroticism, was positively associated with smoking and alcohol drinking. After multivariate adjustment, neuroticism was strongly associated with each of 3 SWB measures. The multivariate-adjusted odds ratios for the highest versus lowest quintile of neuroticism were 6.09 (95% confidence interval [CI], 5.05-7.33) for perceived stress; 0.21 (95% CI, 0.18-0.25) for good health condition; and 0.26 (95% CI, 0.22-0.31) for life satisfaction. Extraversion showed no clear association with the SWB measures.

CONCLUSIONS

The neuroticism and extraversion scales were associated with health behaviours and BMI differently. The neuroticism scale, but not the extraversion scale, was strongly associated with higher perception of stress, poorer perceived health, and lower satisfaction with life in a Japanese population.

Short self-reported sleep duration and suicidal behavior: a cross-sectional study

BACKGROUND

Prior studies on the association between sleep disturbances and suicidal behavior did not explore whether or not short sleep is a marker of suicide intent, lethality or risk.

DESIGN

Cross-sectional.

PARTICIPANTS

Suicide attempters (SAs) (n=434). Controls included 83 psychiatric inpatients who have never been SAs, and 509 healthy controls.

MEASUREMENTS

Short sleep was defined by self-assessment as ≤ 5 h per day. The MINI and the DSM-IV version of the International Personality Disorder Examination Screening Questionnaire were used to diagnose Axis I and Axis II diagnoses, respectively. Suicide intent and lethality were evaluated through the Beck's Suicidal Intent Scale (SIS) and the Risk-Rescue Rating Scale (RRRS), respectively. Beck's Medical Lethality Scale (BMLS) was administered to assess the degree of medical injury, and the SAD PERSONS mnemonic scale was used to evaluate suicide risk.

STATISTICAL ANALYSES

Chi-square tests and logistic regression analyses explored frequencies of short sleep in 3 samples. Chi-square tests explored whether or not suicide intent, lethality and risk were greater in SAs with short-sleep versus those without short-sleep.

RESULTS

Short sleep was more prevalent in SAs than in psychiatric controls only in males. In female SAs, short sleep was significantly associated with several SIS items and high scores in the SAD PERSONS.

LIMITATIONS

Sleep duration was assessed only by self-report.

CONCLUSIONS

The association between short sleep and suicidal behavior may be partly explained by confounders. Short sleep may be a marker of severity of suicidal behavior among female SAs.

Psychosocial correlates of aspects of sleep quality in community-dwelling Irish older adults

OBJECTIVES

While it is known that psychosocial factors affect overall sleep quality, there is little consensus on the factors that affect different aspects of sleep. The Pittsburgh Sleep Quality Index (PSQI) provides a means of examining these separate aspects of sleep.

METHOD

This study investigated whether the different components of the PSQI are affected by different psychosocial factors, or whether all aspects of sleep are associated with the same factors. 505 community-dwelling older adults took part in this study. Psychosocial status, comprising of measures of depression, anxiety, perceived stress, social and emotional loneliness and personality, was assessed for each participant. Health-related factors (pain, comorbidities, polypharmacy) as well as age and gender were also measured.

RESULTS

Neuroticism, depression, anxiety and age accounted for overall sleep quality. Further analyses revealed that different psychosocial and health-related factors such as pain, loneliness and personality accounted for scores in the different components.

CONCLUSION

Interventions for poor sleep quality may depend on the aspect of sleep affected in the individual, and treatment may be contingent on a number of different psychosocial variables. Future research could focus on developing personalised treatment programs for older adults with sleep complaints.

Neurochemical and neuropharmacological aspects of circadian disruptions: an introduction to asynchronization

Circadian disruptions are common in modern society, and there is an urgent need for effective treatment strategies. According to standard diagnostic criteria, most adolescents showing both insomnia and daytime sleepiness are diagnosed as having behavioral-induced sleep efficiency syndrome resulting from insomnia due to inadequate sleep hygiene. However, a simple intervention of adequate sleep hygiene often fails to treat them. As a solution to this clinical problem, the present review first overviews the basic neurochemical and neuropharmachological aspects of sleep and circadian rhythm regulation, then explains several circadian disruptions from similar viewpoints, and finally introduces the clinical notion of asynchronization. Asynchronization is designated to explain the pathophysiology/pathogenesis of exhibition of both insomnia and hypersomnia in adolescents, which comprises disturbances in various aspects of biological rhythms. The major triggers for asynchronization are considered to be a combination of light exposure during the night, which disturbs the biological clock and decreases melatonin secretion, as well as a lack of light exposure in the morning, which prohibits normal synchronization of the biological clock to the 24-hour cycle of the earth and decreases the activity of serotonin. In the chronic phase of asynchronization, involvement of both wake- and sleep-promoting systems is suggested. Both conventional and alternative therapeutic approaches for potential treatment of asynchronization are suggested.

Demographic factors, fatigue, and driving accidents: An examination of the published literature

This article reviews the literature pertaining to the association between demographic variables (e.g., age, sex, race, socio-economic status) with fatigue, and when feasible, accident risk. It also explores their potential influence and interaction with some working arrangements, commute time, personality characteristics, and circadian chronotype. Fatigue has been implicated in a range of impairments that can have detrimental effects on individuals, and it is differentially associated with conventional demographic variables. However, several major methodological limitations prevent clear conclusions. First, there is absence of a shared definition both within and across disciplines. Second, although fatigue has been investigated using a variety of diverse designs, they have either been too weak to substantiate causality or lacked ecological validity. Third, while both subjective and objective measures have been used as dependent variables, fatigue has been more often found to be more strongly linked with the former. Fourth, with the exception of age and sex, the influence of other demographic variables is unknown, since they have not yet been concomitantly assessed. In instances when they have been assessed and included in statistical analyses, they are considered as covariates or confounders; thus, their contribution to the outcome variable is controlled for, rather than being a planned aspect of investigation. Because the interaction of demographic factors with fatigue is largely a neglected area of study, we recommend greater interdisciplinary collaborations, incorporation of multiple demographic variables as independent factors, and use of within-participant analyses. These recommendations would provide meaningful results that may be used to inform public policy and preventive strategies.

Insomnia and suicidal behaviour in prisoners

Insomnia has been associated with suicidality. Prisoners have an increased risk of both insomnia and suicidal behaviour. Therefore, it was decided to examine for a relationship between insomnia and suicidal behaviour in a large group of 1420 prisoners. Prisoners had a semi-structured psychiatric interview, which included the Hamilton Depression Rating Scale (HDRS), and completed the Childhood Trauma Questionnaire, Eysenck Personality Questionnaire, Spielberg Anger Expression Inventory and Connor-Davidson Resilience Scale. It was found that 568 (61.2%) of the prisoners scored in the insomnia cluster of the HDRS and that 183 (12.8%) had attempted suicide. Regression analyses showed that insomnia was significantly and independently associated with a lifetime history of attempting suicide. Insomnia was also significantly related to actual suicidality. After controlling for confounders, axis 1 psychiatric disorder, childhood trauma, neuroticism, low resilience, and anger were significantly associated with insomnia in male prisoners. These data suggest the possibility of a relationship between insomnia and suicidality in prisoners. Assessing insomnia may be helpful when evaluating the risk of suicidality in prisoners.

Neuroticism mediates the relationship between childhood adversity and adult sleep quality

This study investigated the relationship of childhood adversity and adult sleep quality in 327 college students (91 males), with a mean age of 18.9 years (SD = 2.1) and also examined whether neuroticism significantly mediated the observed association. Regression findings indicate that the relationship between childhood adversity and adult sleep quality is significant, and that there is a stronger association in men. Furthermore, a bootstrapping approach to testing the significance of the indirect effect (i.e., mediation) indicated that neuroticism mediated this relationship in both men and women. These data suggest that otherwise healthy young adults with a history of childhood adversity are at increased risk for sleep disturbance. Neuroticism may represent a potential target for change in future insomnia interventions, particularly in adults with a history of childhood adversity.

Morningness-eveningness and depression: preliminary evidence for the role of the behavioral activation system and positive affect

There is considerable evidence of circadian rhythm abnormalities in mood disorders. Morningness-eveningness, the degree to which people prefer organizing their activity and sleep patterns toward the morning or evening, is related to circadian phase and is associated with mood, with relatively greater psychological distress among evening types. Given that circadian rhythms may also relate to the Behavioral Activation System (BAS) and positive affect (PA), but not to the Behavioral Inhibition System (BIS) or negative affect (NA), it was hypothesized that individual differences in BAS sensitivity and levels of PA, but not BIS and NA, would explain the association between morningness-eveningness and depression in a sample of 208 individuals with a range of depressive symptomatology. As predicted, increasing eveningness was associated with greater depression, lower BAS, and lower PA, but not directly associated with NA. Path analyses supported a model wherein morningness-eveningness is associated with depression via multi-step indirect paths including BAS-Reward Responsiveness, PA, and NA. A path between BIS and depression was distinct from the one involving morningness-eveningness. A variety of alternative path models all provided a weaker fit to the data. Thus, results were consistent with the BAS and PA mediating the effects of morningness-eveningness on depression.

Do restless legs syndrome (RLS) and periodic limb movements of sleep (PLMS) play a role in nocturnal hypertension and increased cardiovascular risk of renally impaired patients?

Hypertension can cause or promote renal failure and is related to cardiovascular mortality, the major cause of death in patients with renal impairment. Changes in the circadian BP pattern, particularly the blunting or reversal of the nocturnal decline in BP, are common in chronic renal failure. These changes in turn are among the major determinants of left ventricular hypertrophy. Using a chronobiological approach, it is possible to obtain better insight into the reciprocal relationship between hypertension, renal disease, and increased cardiovascular risk of renal patients. Disruption of the normal circadian rhythm of rest/activity may be hypothesized to underlie the high cardiovascular morbidity and mortality of such patients. Epidemiological studies reveal that hemodialysis patients experience poor subjective sleep quality and insomnia and, in comparison to healthy persons, are more likely to show shorter sleep duration and lower sleep efficiency. Sleep apnea may be present and is usually investigated in these patients; however, the prevalence of restless legs syndrome (RLS), which is high in dialysis patients and which has been associated with increased risk for cardiovascular disease in the general population, could also play a role in the pathogenesis of sleep-time hypertension in renal patients. Careful assessment of sleep quality, in particular, diagnostic screening for RLS and periodic limb movements (PLM) in renal patients, is highly recommended. In renal failure, attention to sleep quality and related perturbations of the sleep/wake cycle may help prevent the occurrence and progression of cardiovascular disease.

Assessment of chronotype in four- to eleven-year-old children: reliability and validity of the Children's Chronotype Questionnaire (CCTQ)

Individual differences in circadian phase preference ("chronotype") are linked to sleep schedule variability, psychosocial functioning, and specific properties of the circadian clock. While much is known about the development, distribution, and variability of chronotype in adolescents and adults, assessment in prepubertal children has been hindered by a lack of appropriate, reliable, and valid measures. This study presents a detailed description of the assessment of children's chronotype by the Children's ChronoType Questionnaire (CCTQ). The CCTQ is a parent-report, 27-item mixed-format questionnaire resulting in multiple measures of chronotype in 4- to 11-yr-old children: the midsleep point on free days (MSF), a morningness/eveningness scale (M/E) score, and a five-point chronotype (CT) score. The study provides validity data using actigraphy as well as test-retest reliability data for all three chronotype measures and sleep/wake parameters. Overall, the findings indicate moderate to strong agreement between the three measures, adequate associations between chronotype measures and sleep/wake parameters assessed by actigraphy, and excellent temporal stability (reliability).

Comparison of sleep/wake parameters for self-monitoring bipolar disorder

BACKGROUND

Psychosocial interventions may teach patients with bipolar disorder to successfully detect warning signs of relapse. These interventions often include ongoing self-monitoring of sleep. We previously reported that a change in sleep duration (sleep plus bedrest) of >3 h may indicate that a mood change is imminent. This analysis further investigated whether sleep duration, sleep onset or sleep offset was the most useful sleep/wake parameter to monitor for an oncoming mood change.

METHODS

101 adult outpatients receiving treatment as usual recorded mood, sleep and medications every day on a home computer for a mean of 265+/-103 days. A daily time series of mood, sleep duration (sleep plus bedrest), sleep onset and sleep offset was constructed for each patient. After applying an ARIMA (0,1,1) filter, a cross correlation function was used to analyze the temporal relationship between the residuals for lags of +/-7 days.

RESULTS

Less frequent significant correlations were found between a change in either sleep onset or sleep offset and mood, than between sleep duration and mood. Patients with a significant correlation between sleep duration and mood included 86% of those with a significant correlation between sleep onset or sleep offset and mood. Mean sleep duration when euthymic was long (> or =8 h in 89% of patients, > or =9 h in 51% of patients).

LIMITATIONS

Self-reported data, naturalistic study, and computer access required.

CONCLUSIONS

Self-monitoring of sleep duration is recommended for patients with bipolar disorder. Better understanding of the long sleep duration of euthymic patients is required.

Relationship between circadian typology and big five personality domains

We explored the relationship between personality, based on the five-factor model, and circadian preference. To this end, 503 participants (280 females, 223 males) were administered the Morningness-Eveningness Questionnaire (MEQ) and the self-report version of the Big Five Observer (BFO) to determine circadian preference and personality features, respectively. Morning types scored significantly higher than evening and intermediate types on the conscientiousness factor. Evening types were found to be more neurotic than morning types. With reference to the big five personality model, our data, together with those of all the previous studies, indicate that the conscientiousness domain is the one that best discriminates among the three circadian types. Results are discussed with reference to neurobiological models of personality.

A newly proposed disease condition produced by light exposure during night: asynchronization

The bedtime of preschoolers/pupils/students in Japan has become progressively later with the result sleep duration has become progressively shorter. With these changes, more than half of the preschoolers/pupils/students in Japan recently have complained of daytime sleepiness, while approximately one quarter of junior and senior high school students in Japan reportedly suffer from insomnia. These preschoolers/pupils/students may be suffering from behaviorally induced insufficient sleep syndrome due to inadequate sleep hygiene. If this diagnosis is correct, they should be free from these complaints after obtaining sufficient sleep by avoiding inadequate sleep hygiene. However, such a therapeutic approach often fails. Although social factors are often involved in these sleep disturbances, a novel clinical notion--asynchronization--can further a deeper understanding of the pathophysiology of these disturbances. The essence of asynchronization is a disturbance in various aspects (e.g., cycle, amplitude, phase and interrelationship) of the biological rhythms that normally exhibit circadian oscillation, presumably involving decreased activity of the serotonergic system. The major trigger of asynchronization is hypothesized to be a combination of light exposure during the night and a lack of light exposure in the morning. In addition to basic principles of morning light and an avoidance of nocturnal light exposure, presumable potential therapeutic approaches for asynchronization involve both conventional ones (light therapy, medications (hypnotics, antidepressants, melatonin, vitamin B12), physical activation, chronotherapy) and alternative ones (kampo, pulse therapy, direct contact, control of the autonomic nervous system, respiration (qigong, tanden breathing), chewing, crawling). A morning-type behavioral preference is described in several of the traditional textbooks for good health. The author recommends a morning-type behavioral lifestyle as a way to reduce behavioral/emotional problems, and to lessen the likelihood of falling into asynchronization.

Association between sleep behavior and sleep-related factors among university students in Hong Kong

Sleep problems among university students are common; however, the association between many sleep-related factors and sleep behaviors is still unclear. The purpose of this study is to examine different sleep behaviors and sleep-related factors influencing such behaviors in university students. A descriptive survey was conducted on 400 university students in Hong Kong. The instruments for data collection consisted of the Pittsburgh Sleep Quality Index (PSQI), a sleep hygiene practice questionnaire, demographic data, and other sleep-related factors. The results reveal that 57.5% of the 400 university students are poor sleepers. Sex, year of study, sleep hygiene practice, and perceived adequate sleep in the past month all demonstrate significant associations with poor sleepers. A high prevalence of sleep-related problems among college students is confirmed and associated factors are identified. Students should be encouraged to follow sleep hygiene practice, adequate time management for academic and social activities, and suitable stress-relieving measures.

A study of the association between sleep habits and problematic behaviors in preschool children

This preliminary study examined the association between sleep habits and problematic behaviors in healthy preschool children using an internationally standardized method. Two groups of 4-6-yr-old healthy Japanese children were recruited. Children in Group A (n=68) met one or more of the following three conditions: they went out from their home with adults after 21:00 h two or more times a week, they went to bed after 23:00 h four or more times a week, and they returned home after 21:00 h three or more times a week, while those in Group B (n=67) met none of these conditions. Sleep-wake logs and the Child Behavior Checklist (CBCL)/4-18 were completed daily for two weeks. The CBCL consists of questions with 113 items categorized into eight subscale items: (I) Withdrawn, (II) Somatic complaints, (III) Anxious/depressed, (IV) Social problems, (V) Thought problems, (VI) Attention problems, (VII) Delinquent behavior, and (VIII) Aggressive behavior. Internalizing (I+II+III), externalizing (VII+VIII), and total scale scores were also derived. Generally, the higher the score, the greater the likelihood of problematic behaviors in that scale. We compared both the CBCL scores and distribution of the CBCL score-determined clinical classification of behavior (normal, borderline, and abnormal) between the groups. Correlation coefficients between CBCL scores and each of the seven indices of the studied sleep habits (wake-up times, bedtimes, nocturnal sleep duration, nap duration, total sleep duration, and range of variation in wake-up and bedtime) were also assessed. Group A children showed significantly shorter average nocturnal sleep, nap, and total sleep duration, significantly later average bedtimes and wake-up times, and a significantly greater range of variation in bedtimes and wake-up times than Group B children. The CBCL score of the total scale was significantly higher in Group A than Group B children. The distribution of the clinical classifications of behavior between the two groups showed no significant differences. Although nocturnal sleep, nap, and total sleep duration did not correlate with total CBCL score, it showed a high positive correlation with wake-up times, bedtimes, and ranges of variation in both wake-up and bed times. The distribution of the clinical classification for the total scale showed significant differences between early and late risers, and also between regular and irregular sleepers. The number of children classified as normal for the total scale score was higher in early risers and regular sleepers than in late risers and irregular sleepers. Preschool children of Group A, late risers, late sleepers, irregular risers, and irregular sleepers were likely to show problematic behaviors.