Morningness and eveningness: the free cortisol rise after awakening in "early birds" and "night owls"

We investigated salivary cortisol profiles in the first hour after awakening in morning versus evening chronotypes. Chronotypes were defined by Horne and Ostberg's Owl-and-Lark-Questionnaire. In a sample of 112 healthy, day-active young men, we identified 9 morning and 29 evening chronotypes. Saliva samples were collected 0, 30, 45, and 60min after awakening on 2 consecutive days. Log-transformed cortisol levels were analyzed with General Linear Model procedures (GLMs) and awakening time and sleep duration were entered as covariates. On both days, a significant main effect of chronotype emerged (both p=0.02), and this effect could not be explained by differences in awakening time or sleep duration. The present data support the idea that morning relative to evening chronotypes might show higher cortisol levels in the first hour after awakening. In sum, individual chronotype should be acknowledged as one further possible source of interindividual variability in the cortisol rise after awakening.     

Patterns of salivary cortisol levels can manifest work stress in emergency care providers

To develop objective assessments of work fatigue, we investigated the patterns of changes in salivary cortisol levels in emergency care providers working extended work shifts. Fourteen subjects, comprising seven physicians and seven physician assistants, provided unstimulated saliva samples at regular intervals over the course of a 24-h work shift and over their subsequent free day. There was a significant time effect, with early morning cortisol levels being significantly attenuated following the work shift. Native diurnal variations varied by gender, with the female subjects manifesting greater cortisol levels. Physicians also had higher cortisol profiles even though their wake–rest cycles were similar to those of the physician assistants. Our results suggest that temporal changes, as well as diurnal similarities, in the salivary cortisol patterns can reflect work-related stress and recovery. In particular, early morning cortisol levels may manifest individual reactivity to work stressors as well as sleep deprivation.     

Bi-directional associations between psychological arousal, cortisol, and sleep

The aim was to elucidate the possible bi-directional relation between daytime psychological arousal, cortisol, and self-reported sleep in a group of healthy employees in active employment. Logbook ratings of sleep (Karolinska Sleep Questionnaire), stress, and energy, as well as positive and negative experiences in work and private life, were collected together with salivary cortisol over 3 days (n = 265). Higher bedtime ratings of stress and problems during the day were associated with morning ratings of poor sleep. Poorer morning ratings of sleep were associated with higher ratings of stress and problems during the day. The results underpin the possibility that arousal and poor sleep might create a self-reinforcing vicious circle that negatively affects a person's well-being.     

Physiologic markers of chronic stress in premenopausal,middle-aged women

OBJECTIVE: The purpose of this study was to identify physiological markers of chronic stress in middle-aged women that can be assessed simply and are thus feasible for introduction into large-scale, epidemiologic studies of aging. METHODS: Subjects were 40 nonsmoking, premenopausal women between the ages of 42 and 52 years, 20 of whom were chronically stressed because of undergoing a divorce or separation and 20 of whom were nonstressed because of being in stable marriages. Stressed and nonstressed women were matched for age, ethnicity, and education. Hypotheses focused on morning and evening salivary cortisol, overnight urinary catecholamines, cortisol, and testosterone, and platelet catecholamines. RESULTS: Relative to the nonstressed control subjects, the stressed women had elevated evening (9 PM) salivary cortisols, a finding that was observed on both days (mixed effects model: effect = 0.44; se = 0.14, p =.003). Support for the importance of the HPA axis was provided by the observation that the stressed women had less suppression of salivary cortisol in response to low-dose dexamethasone. Contrary to our hypothesis that stressed women would have lower overnight urinary testosterone, they had higher testosterone on day 2 (stressed = 0.76 ng/mg, nonstressed = 0.55 ng/mg; p =.04). Post hoc repeated measures analysis revealed a significant group effect over all time periods of observation (F = 5.48, p =.03, df = 1,18). Stressed women had a nonsignificant trend toward elevated platelet catecholamines. No association was found for overnight urinary catecholamines or cortisol. CONCLUSIONS: Promising markers of marital upheaval in middle-aged women are evening salivary cortisol and urinary testosterone from a first morning void. Replication of these findings with the same and different chronic stressors and with women of older ages is needed. The low cost and minimal burden of these potential markers makes it feasible to introduce them into large-scale epidemiologic studies of health in aging women.     

唾液皮质醇检测在抑郁症诊断中的应用探讨

研究抑郁症患者与健康人早晨唾液皮质醇水平的差异,探讨唾液皮质醇检测对抑郁症诊断的应用价值。早晨收集31例抑郁症患者（患者组）和31名健康人（对照组）的唾液样本,采用酶免疫法（EIA）测定其皮质醇水平;同时以汉密尔顿抑郁量表（24项,HAMD）评定研究对象的抑郁程度。患者组唾液皮质醇水平明显高于对照组（P＆lt;0.01）。唾液皮质醇水平和HAMD评分在对照组中呈正相关（Spearman相关系数=0.663,P＆lt;0.01）;在患者组则无显著相关（P=0.199）。用受试者工作特征（receiver operating characteristic,ROC）曲线分析唾液皮质醇对抑郁症的诊断价值,曲线下面积为0.771（95%可信区间：0.654~0.887）;11.75nmol/L为综合考虑灵敏度和特异性时的最佳诊断阈值,其对应的灵敏度为64.5%,特异性为77.4%;16.73nmol/L是特异性为100%时的诊断阈值,其对应的灵敏度为41.9%。抑郁症患者早晨唾液皮质醇水平比健康人高,唾液皮质醇检测可作为抑郁症诊断的一种辅助手段,但尚不能用于判断患者的抑郁程度。     

Relationship between salivary cortisol and depression in adolescent survivors of a major natural disaster

The purpose of this study was to determine the utility of salivary cortisol levels for screening mental states such as depression in adolescents following a natural disaster. We examined the relationship of salivary cortisol levels in adolescent survivors of the 2011 Tohoku Earthquake with the depression subscale of the 28-item General Health Questionnaire (GHQ). Subjects were 63 adolescent survivors (age = 14.29 years ± 0.51) who were administered the GHQ and provided saliva samples thrice daily (morning, afternoon and evening) over the course of 3 days. Based on the GHQ-depression subscores, subjects were divided into low and high depression groups. About 22 % of the subjects were classified into the high symptom group. When data collected over 3 days were used, a significant difference was observed between the two groups in the salivary cortisol levels at the evening time point as well the ratio of the morning/evening levels (p < 0.05). Analyzed by means of receiver-operating characteristic curves, the morning/evening ratios showed a good power in discriminating between subjects with and without depressive symptoms. Our study suggests that repeated measurement of salivary cortisol levels over 3 days has utility in screening for depressive states in adolescents following a natural disaster.     

The relationship between long-term job strain and morning and evening saliva cortisol secretion among white-collar workers

The objective of this study was to assess long-term job strain impact on morning and evening salivary cortisol secretion. In all 77 white-collar workers (31% women; sample mean age, 42 years at baseline) volunteered to sample morning (immediately after waking up) and evening (10 p.m.) salivary cortisol for 7 consecutive days. By median split on aggregated self-reported isostrain from three consecutive questionnaires distributed in a period of approximately 3.5 years the participants were classified into a high or low long-term isostrain condition. Regardless of strain condition, there was a significant reduction in morning salivary cortisol secretion from the working week to the weekend, whereas evening salivary cortisol secretion showed no significant variation during the week. Although chronic isostrain did not affect the morning saliva cortisol measures, evening cortisol secretion was significantly elevated in the chronic high isostrain group throughout the whole week. The elevated evening cortisol measures associated with chronic high strain are concordant with the findings in other studies on long-term strain.     

The temporal relationships between sleep, cortisol, and lung functioning in youth with asthma

OBJECTIVES: This study tested the directionality of the association between sleep and health outcomes in youth with asthma. METHOD: Thirty-eight youth with asthma (aged 9-19) completed a daily diary study on sleep, asthma symptoms, peak expiratory flow (PEF) measures, and salivary cortisol samples. RESULTS: Greater quantity of sleep predicted lower PEF% [beta(32) = -.33, p =.02], and lower daily cortisol output [beta(33) = -.31, p =.07] the following day. Additionally, poorer self-reported sleep quality predicted more severe symptoms the next day [beta(33) =.27, p =.05]. In contrast, PEF%, cortisol, and asthma symptoms did not significantly predict self-reported sleep quantity or quality the next night. CONCLUSIONS: Results suggest that sleep may affect subsequent health outcomes, rather than asthma impacting subsequent sleep, indicating the potential benefits of targeting sleep behaviors in youth with asthma.     

Salivary cortisol in nursery-reared rhesus monkeys: Reactivity to peer interactions and altered circadian activity

Five nursery-reared rhesus (Macaca mulatta) infants were studied on 8 consecutive days over a period of 2 weeks when they ranged from 4 to 5.5 months. Saliva cortisol samples were obtained by giving each animal, while in its individual home cage, a 6-in. cotton dental roll pretreated with sugared fruit-drink crystals and dried. Subjects were allowed to mouth the cotton roll for 10 min during each collection period. Saliva was then expressed from the cotton and analyzed by radioimmune assay. Samples were collected at 0830, 1100, 1400, and 1630 hr on each of the 8 days. On four of the days, 2-hr peer socialization sessions were imposed between 1200 and 1400 hr. Significant time-of-day effects were obtained. Values tended to be low at 0830 hr, rising significantly to peak levels at 1100 hr, and then declining over the 1400-hr and 1630-hr sampling periods. All 4 subjects with sufficient samples had higher average cortisol concentrations when the 1400-hr sampling followed peer-socialization sessions, compared to no-socialization days. This difference was only marginally significant by paired t test, however. These results (a) support the feasibility of using noninvasive salivary sampling procedures with infant monkeys, and (b) indicate that salivary cortisol measures are sensitive to daily rhythms. Unexpectedly, the results also raise the possibility that nursery-reared infant rhesus macaques may be phase-delayed in their HPA rhythm, with the morning peak occurring several hours after rather than in the hour before lights-on and the morning feeding. © 1995 John Wiley & Sons, Inc.     

Differences in sleep-wake habits and EEG sleep variables between active morning and evening subjects

This article is a survey study, followed by an experimental study, examining the differences of sleep-wake habits and sleep electroencephalographic (EEG) variables between morning and evening type subjects (Ss). In the survey study, the Japanese version of the Horne and Ostberg Morningness-Eveningness Questionnaire and Life Habits Inventory (LHI) were administered to approximately 1,500 university students. The survey results showed that the two types were significantly different from each other in terms of retiring and arising time, sleep latency, mood on arising, nap, adequate amount of sleep, number of times of staying awake all night, and variability in bedtime, arising time, and sleep length. These results suggested that evening type Ss had more irregular and/or flexible sleep-wake habits than morning type Ss. In the experimental study, 10 morning and 11 evening type Ss were selected from the population included in the survey study, and polysomnograms were obtained. The results showed that only in rapid eye movement (REM) latency did morning type Ss significantly differ from evening type Ss. REM latency might be related to personality factors, particularly to neuroticism and anxiety.     

Correlations between cortisol level and internalizing disposition of young children are increased by selecting optimal sampling times and aggregating data

To determine the optimal time for testing the association between personality traits and cortisol levels, and the number of sampling days needed for reliable results to be obtained for preschool-aged children, ambulatory salivary sampling for cortisol was performed on 39 preschoolers at four different times for 10 consecutive school days. A repeated-measure ANOVA revealed a significant day effect, time effect, and day by time interaction. Further tests of day effect revealed that within-subject cortisol levels differed significantly in the early morning, early afternoon, and late afternoon cortisol data, but not in the late morning; group average levels of cortisol assessed in the early mornings are significantly different among the days, so are the ones measured in early and late afternoon. Mid-afternoon cortisol levels showed the most significant day effect and the highest correlation with internalizing disposition. In addition, the probability of finding significant correlations between cortisol levels and internalizing disposition increased with a greater number of aggregated cortisol measures. The tentative conclusion is that to avoid under-representation of the correlations between cortisol levels and personality variables, both sampling time selection and data aggregation are important.     

Circadian phase in delayed sleep phase syndrome: predictors and temporal stability across multiple assessments

STUDY OBJECTIVES: To assess temporal stability across multiple assessments and predictors of circadian phase in participants with delayed sleep phase syndrome (DSPS), relative to normal-sleeping matched controls. DESIGN: Circadian phase was assessed by salivary dim light melatonin onset (DLMO) during 3 laboratory visits, separated by at least 5 days--2 scheduled at the end of the week (Friday) and 1 scheduled at the end of the weekend (Sunday). PATIENTS: Eight young volunteers who met International Classification of Sleep Disorders-Revised criteria for DSPS, and 8 age- and sex-matched controls (age range 19-27 years old). INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: As expected, salivary DLMO occurred significantly later in patients with DSPS than in controls (F 10.561, p = .006). However, circadian phase did not change significantly across the 3 DLMO assessments in either group. Estimations of circadian phase were not significantly different in the assessments conducted on weekdays versus weekends. Predictors of circadian phase included time of morning light exposure (R2 = 0.777; p < .001), recent wake time (R2 = 0.701, p < .001), and self-reported chronotype (R2 = 0.320, p = .016). DLMO preceded wake time in both groups by approximately 10.75 hours. CONCLUSIONS: Across serial laboratory assessments on an ad lib sleep schedule, patients with DSPS appeared more similar to than different from normal-sleeping control subjects, except for a stable delay in circadian phase.     

Poor sleep the night before an experimental stress task is associated with reduced cortisol reactivity in healthy women

Sleep disruption is a growing problem that may have serious health effects. As stress-induced increases in cortisol are thought to be a key adaptive process it is important to examine how this response is affected by sleep. The current study investigated the association of four sleep parameters (objective/subjectively measured sleep quality and quantity) and subsequent salivary cortisol reactivity (maximal change from baseline) to an experimental stressor in 53 healthy women. Objective actigraphy monitoring and self-report diaries were used to assess sleep. Results revealed that individuals with lower objective sleep quality (wake percentage during sleep) had a blunted response to the experimental stressor. No associations were found between cortisol reactivity and actigraphy-derived sleep quantity, or either of the self-reported sleep variables. Results are discussed with regard to the possible adverse health effects that may result from poor sleep quality and a blunted cortisol response to stress.     

Diurnal preference, sleep habits, circadian sleep propensity and melatonin rhythm in healthy human subjects

After 24-h sleep deprivation, 33 healthy young subjects entered the 10/20 min ultra-short sleep–wake schedule for 26 h. Melatonin rhythm was hourly assessed simultaneously. Results indicated that morning preference was significantly correlated with habitual sleep onset (r=−0.41, P=0.04), habitual sleep offset (r=−0.52, P=0.002), melatonin peak time (r=−0.36, P=0.04), and sleep propensity onset time (r=−0.36, P=0.04). The intervals between habitual sleep mid-point and melatonin peak time and between habitual sleep mid-point and sleep propensity onset time were significantly longer in morning-preference subjects than in evening-preference subjects (P<0.05). These findings suggest that the variance of diurnal preference may be related to differences in phase relations between habitual sleep timing and the circadian pacemaker.     

Child maltreatment and allostatic load: consequences for physical and mental health in children from low-income families

Child maltreatment and biomarkers of allostatic load were investigated in relation to child health problems and psychological symptomatology. Participants attended a summer research day camp and included 137 maltreated and 110 nonmaltreated low-income children, who were aged 8 to 10 years (M = 9.42) and racially and ethnically diverse; 52% were male. Measurements obtained included salivary cortisol and dehydroepiandosterone, body mass index, waist-hip ratio, and blood pressure; these indicators provided a composite index of allostatic load. Child self-report and camp adult-rater reports of child symptomatology were obtained; mothers provided information on health problems. The results indicated that higher allostatic load and child maltreatment status independently predicted poorer health outcomes and greater behavior problems. Moderation effects indicated that allostatic load was related to somatic complaints, attention problems, and thought problems only among maltreated children. Risks associated with high waist-hip ratio, low morning cortisol, and high morning dehydroepiandosterone also were related to depressive symptoms only for maltreated children. The results support an allostatic load conceptualization of the impact of high environmental stress and child abuse and neglect on child health and behavioral outcomes and have important implications for long-term physical and mental health.     

The transition of sleep-wake patterns in early adolescence

STUDY OBJECTIVE: To examine the relationship between school grade level and sleep-phase preference in early adolescence. DESIGN: A school-based cross-sectional study using a Sleep Habit Questionnaire. SETTING: NA. PARTICIPANTS: One thousand five hundred and seventy-two students, grade 4 to grade 8, from 3 junior high schools and 3 elementary schools in Taipei were recruited using multistage sampling method. The response rates were 98.4% (1547) for participants and 95.9% (1509) for their parents. INTERVENTIONS: NA. MEASUREMENTS AND RESULTS: Each student participant completed a Sleep Habit Questionnaire, including sleep schedules, the Morningness/Eveningness (M/E) scale, the Pubertal Developmental Scale, and the Sleepiness Scale. The morning (N = 367) and evening (N = 364) groups were operationally defined as participants with the top 25% and the bottom 25% of the M/E score, respectively. A mixed model was used in data analysis to address the cluster effects arising from the school-based study. We found that the M/E score decreased and the proportion of the evening type increased across grade 4 to grade 8. The evening type was associated with decreased nocturnal sleep and later bedtimes and rise times, as well as with increased daytime sleepiness and compensation for sleep on weekends. CONCLUSIONS: Our findings support the hypothesis that school grade level is significantly associated with the transition to evening type in early adolescence. We report that environmental factors may play a more important role than biologic factors, such as age, sex, and pubertal development, in the transition from morning type to evening type at early adolescence. Future longitudinal study is necessary to determine the trajectories of sleep-wake patterns in adolescents and their predictors.     

Dampening of the cortisol response to handling at 3 months in human infants and its relation to sleep,circadian cortisol activity,and behavioral distress

The decrease in responsiveness of the hypothalamic–pituitary–adrenocortical (HPA) system is marked over the first months of life. Seventy-eight healthy infants (44 girls), 7 to 15 weeks old, were given a laboratory mock physical examination. Salivary cortisol samples were collected pre- and postexamination and at home. Behavioral state during the examination and home sleep/wake activity were measured. Subjects younger than 11 weeks showed an increase in pre- to postexamination cortisol, while older subjects did not. Further, there was no decrease in behavioral distress to the examination with age. Infants who showed an early-morning peak (EMP) in home cortisol levels were significantly older and were likely to be those who slept through the night. However, the presence of an EMP was not associated with a lack of cortisol response to the examination. The decrease in cortisol responsiveness witnessed around the age of 3 months is presumably due to other processes associated with age, and not with the expression of the day–night rhythm in basal cortisol. © 1998 John Wiley & Sons, Inc. Dev Psychobiol 33: 327–337, 1998     

Correlates of sleep-wake patterns among children and young adolescents in Taiwan

STUDY OBJECTIVE: To determine correlates of morning and evening sleep-wake patterns in a community sample of children. DESIGN: A school-based cross-sectional survey. PARTICIPANTS: Sample included 1572 students, grades 4 to 8 (response rate, 98.4%), using a multistage sampling method. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Student participants completed a Sleep Habits Questionnaire, which included sleep schedules, a mood scale, substance use, the morningness/eveningness (M/E) scale, pubertal development scale, sleep disturbance scale, and parental monitoring scale. The morning (n = 367) and evening (n = 364) groups were operationally defined as participants who scored in the top or bottom 25% of the M/E scale, respectively. Linear mixed and tree-based classification models were used to explore correlates of sleep-wake patterns. Our results showed the evening type was associated with older school grade level, increased coffee drinking, moodiness, decreased parental monitoring, daytime sleepiness, and several sleep disturbances, including early insomnia, fear of sleeping in darkness, bedwetting, and going to bed later than 3 am. The 2 most potent discriminators between evening and morning subtypes were higher grade level, an index of age, and moodiness. The association of moodiness with the evening type was greater in boys than girls. CONCLUSIONS: These findings suggest that further research should address explanations for the association between evening type and mood and anxiety symptoms, including order of the effects, developmental factors, environmental determinants of sleep time such as school start time and parental bedtime monitoring, and circadian maturation.     

医学生考前焦虑情绪与唾液皮质醇、睡眠质量、心理健康的关系

目的探讨医学生在期末考试前焦虑情绪与唾液皮质醇、睡眠质量和心理健康的相关性。方法以状态-特质焦虑问卷(STAI-FormY)、唾液皮质醇、匹兹堡睡眠质量指数(PSQI)、症状自评表(SCL-90)为评价工具。采用方便取样的方法,于期末考前5周和考前3天,共测2次,调查某医学院二年级药学专业43名学生的焦虑状态与相关生理、心理指标及其变化趋势。结果高焦虑组的SCL-90总分、日间功能和主观睡眠质量均高于无焦虑组和轻焦虑组,但组间唾液皮质醇没有差异;4周后,状态焦虑没有显著变化,轻度焦虑组的皮质醇水平有明显的下降趋势;相关分析显示,焦虑与SCL-90总分、睡眠总分有显著正相关关系,而与皮质醇没有显著相关关系。结论自评焦虑与心理健康综合水平、主观睡眠质量有较稳定的相关关系,而与唾液皮质醇的相关关系不明确。     

Daily light exposure profiles in older non‐resident extreme morning and evening types

Differences in daily light exposure profiles have been reported, with younger M‐types shown to spend more time in bright light, especially in the morning, compared with E‐types. This study aimed to investigate how patterns of daily light exposure in older non‐resident M‐types and E‐types compare. Sleep diaries were kept during actigraphic measurement of activity and light using the Actiwatch‐L for 14 days in 12 M‐types [eight females, mean ± standard deviation (SD) Horne–Östberg Morning–Eveningness Questionnaire (HÖ MEQ) score 75.2 ± 1.6] and 11 E‐types (seven females, HÖ MEQ 41.5 ± 4.8), over 60 years old, living in their own homes. Light data were log‐transformed, averaged over each hour, and group × time analysis of covariance (ancova ) performed with age as a covariate. M‐types had significantly earlier bed and wake time than E‐types, but there was no significant difference in sleep duration, sleep efficiency or time spent in bed between groups. Daily exposure to light intensity greater than 1000 lux was compared between the two groups, with no significant difference in the duration of exposure to >1000 lux between M‐types and E‐types. Twenty‐four‐hour patterns of light exposure show that M‐types were exposed to higher light intensity at 06:00 h than E‐types. Conversely, E‐types were exposed to higher light intensity between 22:00 and 23:00 h than M‐types. These findings show that differences in daily light exposure patterns found previously in younger M‐types and E‐types are also found in older M‐types and E‐types, but at an earlier clock‐time, confirming the tendency to advance with ageing.