Is the cortisol awakening rise a response to awakening?

Brain preparedness: The proactive role of the cortisol awakening response in hippocampal-prefrontal functional interactions

Upon awakening from nighttime sleep, the stress hormone cortisol in humans exhibits a robust rise within thirty to forty-five minutes. This cortisol awakening response (CAR), a crucial point of reference within the healthy cortisol circadian rhythm, has been linked to various psychological, psychiatric and health-related conditions. The CAR is thought to prepare the brain for anticipated challenges of the upcoming day to maintain one's homeostasis and promote adaptive responses. Using brain imaging with a prospective design and pharmacological manipulation, we investigate the neurobiological mechanisms underlying this preparation function of the CAR across two studies. In Study 1, a robust CAR is predictive of less hippocampal and prefrontal activity, though enhanced functional coupling between those regions during a demanding task hours later in the afternoon. Reduced prefrontal activity is in turn linked to better working memory performance, implicating that the CAR proactively promotes brain preparedness based on improved neurocognitive efficiency. In Study 2, pharmacologically suppressed CAR using Dexamethasone mirrors this proactive effect, which further causes a selective reduction of prefrontal top-down functional modulation over hippocampal activity. These findings establish a causal link between the CAR and its proactive role in optimizing functional brain networks involved in neuroendocrine control, executive function and memory.

Diurnal variation in serum concentrations of cortisol in captive African (Loxodonta africana) and Asian (Elephas maximus) elephants

Cortisol is involved in a broad range of physiological processes and enables animals to adapt to new situations and challenges. Diurnal fluctuations in circulating cortisol concentrations in elephants have been demonstrated based on samples from urine and saliva. The aims of this study were to demonstrate diurnal cortisol fluctuations based on blood samples and compare concentrations between seasons, species, and changes in reproductive hormone concentrations. Nine African (Loxodonta africana) and three Asian (Elephas maximus) elephants at two facilities in the United States were included in this study. Blood samples were collected every 2-3 h at one location and every 1-6 h at another. Peak serum concentrations of cortisol averaged 28 ng/ml for both African and Asian elephants, and diurnal cycles included a fivefold decrease from morning peak to evening nadir concentrations. Diurnal cortisol profiles varied uniquely among individual elephants. During the winter, nadir concentrations of cortisol were slightly higher, and the timing of peak concentrations was less predictable. There was no correlation between diurnal serum concentrations of progesterone and cortisol; however, a significant correlation (p = .02) was identified between serum concentrations of testosterone and cortisol when a time lag of ~2-3 h was considered. The physiological significance of the positive correlations between diurnal serum concentrations of cortisol and testosterone in male elephants remains to be determined. If cortisol concentrations are being used to evaluate elephant health or welfare, samples should be obtained at the same time each day to minimize variation due to diurnal fluctuations, and ideally seasonal variations and individuality in diurnal profiles should also be considered.

Sleep and Circadian Regulation of Cortisol: A Short Review

The central circadian pacemaker (CCP) located in the suprachiasmatic nucleus (SCN) of the hypothalamus drives the 24-hour pattern in cortisol, which functions as the main central synchronizing signal that coordinates peripheral clocks in organs that control whole body metabolism. A superimposed pulsatile pattern of cortisol allows rapid responses that fine tune the body's reaction to changes in the environment. In addition to coordinating metabolic processes to predictable environmental events, cortisol is the main catabolic signal which acts with testosterone, the quintessential male anabolic hormone, to maintain catabolic-anabolic homeostasis in men. Sleep restriction, when sufficiently substantial, increases late afternoon/early evening cortisol, but does not alter 24-hour cortisol; whereas even maximal acute circadian misalignment only slightly delays the cortisol rhythm. Prolonged circadian misalignment decreases overall cortisol exposure. The implications of these regulatory changes on health and disease requires further evaluation.

Pubertal transition with current life stress and support alters longitudinal diurnal cortisol patterns in adolescents exposed to early life adversity

Current and early life stress (ELS) are associated with diurnal cortisol patterns, which themselves are associated with mental and physical health. The pubertal recalibration hypothesis suggests that the social environment can impact dysregulated cortisol patterns for previously ELS-exposed youth as they transition through puberty. This study examined longitudinal change in cortisol awakening response (CAR) and diurnal slope (DS) across puberty as a function of ELS in infancy, current stress, and social support (N = 290, 7-17 years). The CAR and DS were examined thrice annually with an accelerated longitudinal design with nurse-assessed puberty to assess associations between diurnal cortisol and pubertal recalibration with ELS and the current social environment. Exposure to ELS was associated with less steep DS but not changes in CAR, and no evidence of pubertal calibration was found. The DS became less steep for youth in later pubertal stages and as youth progressed through puberty. The CAR was steeper for youth in later pubertal stages. Across the cohort, current life stress and support were associated with changes in the DS and the CAR through the pubertal transition. The pubertal stage and the peripubertal and pubertal social environment may have important implications for adrenocortical functioning with or without exposure to ELS.

Examining the same-day relationship between morning cortisol after awakening, perceived stress in the morning, and physical activity in youth

Most children in the United States currently do not meet physical activity (PA) guidelines, and perceived stress is a known barrier against PA. However, most studies have solely focused on the between-subject (BS) association of stress and PA, whereas the within-subject (WS) relationship remains under-studied in children. This limits our understanding of day-level psychosocial factors that influence children's PA engagement. This study assessed the same-day associations of the Morning Cortisol after Awakening (MCA) and morning perceived stress with moderate-to-vigorous physical activity (MVPA) in children using Ecological Momentary Assessment (EMA) methodologies. The analytic sample consisted of 143 children from Los Angeles in the Mothers and Their Children's Health (MATCH) study. Children collected four saliva samples and wore accelerometers to assess MVPA minutes across four days (two weekdays and two weekend days) during each data collection wave. On weekend days, they also answered a mobile phone EMA survey on perceived stress within 1 h of awakening. Data from four assessment waves, each approximately six months apart, were combined and analyzed cross-sectionally. Multilevel modeling, which adjusts for the nested data structure, was used to test the same-day associations of MCA and weekend morning perceived stress with MVPA. On weekend days when morning perceived stress was higher than usual, participants engaged in more MVPA on the same day (β = 0.79, SE = 0.32, p = 0.02), but no association was found between MCA and MVPA. These findings elucidate same-day factors that predict MVPA in children and inform future WS studies on stress and PA.HighlightIt is unknown how stress influences children's daily activity levels. We tested if two types of stress (self-reported and saliva-measured) are related to children's daily activity. We found that self-reported stress is associated with physical activity, but saliva-measured stress is not.

Circadian fluctuations in glucocorticoid level predict perceptual discrimination sensitivity

Slow neurobiological rhythms, such as the circadian secretion of glucocorticoid (GC) hormones, modulate a variety of body functions. Whether and how endocrine fluctuations also exert an influence on perceptual abilities is largely uncharted. Here, we show that phasic increases in GC availability prove beneficial to auditory discrimination. In an age-varying sample of N = 68 healthy human participants, we characterize the covariation of saliva cortisol with perceptual sensitivity in an auditory pitch discrimination task at five time points across the sleep-wake cycle. First, momentary saliva cortisol levels were captured well by the time relative to wake-up and overall sleep duration. Second, within individuals, higher cortisol levels just prior to behavioral testing predicted better pitch discrimination ability, expressed as a steepened psychometric curve. This effect of GCs held under a set of statistical controls. Our results pave the way for more in-depth studies on neuroendocrinological determinants of sensory encoding and perception.

Work-Related Mental Health Issues in Graduate Student Population

The scientific and educational community is becoming increasingly aware of the impact of current academic working conditions on graduate students' mental health and how this is affecting scientific progress and ultimately society as a whole. Our study aimed to shed light on the work-related mental health issues affecting graduate students, providing a comprehensive research work including psychological and biological assessment. Our findings showed that a sizeable number of graduate student present anxiety, depression, or high burnout and that the time spent in academia plays an important role. The graduate student population displayed a specific work-related mental health issues profile with an altered hypothalamic-pituitary-adrenal (HPA) axis and low levels of work engagement. Finally, graduate students were equally stressed, with less work engagement, and more anxious and depressed than general workers.

Effects of Overtraining Status on the Cortisol Awakening Response-Endocrine and Metabolic Responses on Overtraining Syndrome (EROS-CAR)

The cortisol awakening response (CAR) is a distinct component of the circadian cortisol profile and has promise as a biomarker for the monitoring of athlete readiness and training status. Although some studies have suggested the CAR may be affected by the development of overtraining syndrome (OTS), this has yet to be systematically investigated.

PURPOSE

To compare the CAR and diurnal cortisol slope between athletes diagnosed with OTS, healthy athletes, and sedentary controls.

METHODS

This study was a secondary analysis of data from the Endocrine and Metabolic Responses on Overtraining study. Male participants were recruited to either OTS, healthy athlete, or sedentary control groups. The participants produced saliva samples immediately after waking (S1), 30 minutes after waking (S2), at 16:00 hours, and at 23:00 hours. Salivary cortisol concentration was determined by an electrochemiluminescence assay. Mixed-effects models were used to assess the conditional effect of group (sedentary controls, OTS, and healthy athletes) on the change in cortisol over time. Separate models were fit for the awakening samples (S1 and S2) and for the diurnal slope (linear change across S1, 16:00 h, and 23:00 h).

RESULTS

The models demonstrated significant time-by-group interaction for OTS for the 2 cortisol concentrations collected during the awakening period (β = -9.33, P < .001), but not for the diurnal cortisol slope (β = 0.02, P = .80).

CONCLUSIONS

These results suggest the CAR may be associated with OTS and should be considered within a panel of biomarkers. Further research is necessary to determine whether alterations in the CAR may precede the diagnosis of OTS.

Developmental effects in physiological stress in early adolescents with and without autism spectrum disorder

INTRODUCTION

Humans place high value on how they are socially evaluated by others. The Trier Social Stress Test (TSST) is a well-established measure of social evaluative threat that promotes activation of the hypothalamic pituitary adrenal (HPA) axis and release of cortisol. Higher cortisol responses in typically developing (TD) adolescents are influenced by age and pubertal development especially in later stages. Children with ASD have been shown to exhibit blunted cortisol in response to the TSST although adults with ASD show a more prototypical response. The current study examined physiological stress in early adolescents with ASD and TD. It was hypothesized that TD youth would show elevated cortisol in response to the TSST influenced by age and pubertal stage. In contrast, youth with ASD would show a more diminished stress response yet still show effects for age and pubertal development METHODS: The sample included 241 youth, 138 with ASD (median age=11.25) and 103 TD (median age=11.67). Standardized diagnostic and pubertal development (genital/breast (GB), and pubic hair (PH) stage) physical exams were performed. Salivary cortisol was collected before and after the TSST. Linear mixed effects models examined the effects of baseline cortisol, time, age, sex, pubertal stage, and diagnosis.

RESULTS

We did not find an effect of early pubertal development stage (GB or PH) on cortisol response. There was an interaction between age and TSST timepoint, showing stronger effects for older children across the timeline especially during the stressor. Finally, there was a significant diagnosis by TSST timepoint interaction characterized by a blunted cortisol stress response in youth with ASD compared to TD participants who showed higher cortisol.

DISCUSSION

We found evidence that age contributes to an increase in cortisol in response to social evaluative threat during early adolescence. TD youth exhibit an adaptive elevated stress response to psychosocial threat whereas youth with ASD do not. There may exist a developmental lag in the perception of and stress responsivity to social evaluation which may emerge in older adolescents with ASD.

Integrative Review of Early Life Adversity and Cortisol Regulation in Pregnancy

OBJECTIVE

To synthesize published findings on the relationship between early life adversity and hypothalamic-pituitary-adrenal axis cortisol parameters in pregnant women.

DATA SOURCES

We searched PubMed, CINAHL, and PsycINFO databases using variants and combinations of the keywords early life adversity, pregnancy, hypothalamic-pituitary-adrenal axis, and cortisol.

STUDY SELECTION

We selected articles that included pregnant participants, included measures of cortisol and early life adversity, were published in English in a peer-reviewed journal, and were of sufficient methodologic quality. Date of publication was unrestricted through May 2020.

DATA EXTRACTION

Twenty-five articles met the inclusion criteria and were evaluated for quality and risk of bias. Sources of cortisol included saliva, hair, plasma, and amniotic fluid.

DATA SYNTHESIS

We categorized findings according to four physiologically distinct cortisol output parameters: diurnal (daily pattern), phasic (in response to an acute stressor), tonic (baseline level), and pregnancy-related change. Preliminary evidence suggests that early adversity may be associated with elevated cortisol awakening response (diurnal) and blunted response to acute stressors (phasic), irrespective of other psychosocial symptoms or current stress. For women with high levels of current stress or psychological symptoms, early adversity was associated with higher baseline (tonic) cortisol levels.

CONCLUSION

Early life adversity in women is linked with alterations in cortisol regulation that are apparent during pregnancy. Researchers should examine how variations in each cortisol parameter differentially predict pregnancy health risk behaviors, maternal mental health, and neonatal health outcomes.

Preliminary Results: The Impact of Smartphone Use and Short-Wavelength Light during the Evening on Circadian Rhythm, Sleep and Alertness

Smartphone usage strongly increased in the last decade, especially before bedtime. There is growing evidence that short-wavelength light affects hormonal secretion, thermoregulation, sleep and alertness. Whether blue light filters can attenuate these negative effects is still not clear. Therefore, here, we present preliminary data of 14 male participants (21.93 ± 2.17 years), who spent three nights in the sleep laboratory, reading 90 min either on a smartphone (1) with or (2) without a blue light filter, or (3) on printed material before bedtime. Subjective sleepiness was decreased during reading on a smartphone, but no effects were present on evening objective alertness in a GO/NOGO task. Cortisol was elevated in the morning after reading on the smartphone without a filter, which resulted in a reduced cortisol awakening response. Evening melatonin and nightly vasodilation (i.e., distal-proximal skin temperature gradient) were increased after reading on printed material. Early slow wave sleep/activity and objective alertness in the morning were only reduced after reading without a filter. These results indicate that short-wavelength light affects not only circadian rhythm and evening sleepiness but causes further effects on sleep physiology and alertness in the morning. Using a blue light filter in the evening partially reduces these negative effects.

Chronobiologic parameter changes in patients with major depressive disorder and sleep disturbance treated with adjunctive brexpiprazole: An open-label, flexible-dose, exploratory substudy

BACKGROUND

Circadian rhythm disturbances have been reported in patients with major depressive disorder (MDD). Among these is an increased phase angle between peak cortisol concentration and dim-light melatonin onset (DLMO). The aim of this study was to evaluate changes in chronobiologic parameters of sleep in patients with MDD receiving adjunctive brexpiprazole.

METHODS

This was an interventional, multicenter, open-label, flexible-dose, exploratory study in patients with MDD and inadequate response to antidepressant treatment who were experiencing sleep disturbances. Patients received adjunctive brexpiprazole 2-3 mg/day for 8 weeks. Outcome measures included cortisol and melatonin levels, used to calculate phase angle, and the Biological Rhythms Interview of Assessment in Neuropsychiatry (BRIAN).

RESULTS

The mean (standard error) phase angle between peak cortisol and DLMO increased by 108 (61) minutes from baseline to Week 8 (n = 9). BRIAN Total score changed (improved) by -14.6 (4.6) points from baseline to Week 8 (n = 9). Change in phase angle and BRIAN Total score showed a moderate-to-high correlation (Pearson coefficient: 0.68; 95% confidence limits: 0.04, 0.93; p = 0.040).

LIMITATIONS

This study is limited by its small sample size, and its single-arm, open-label design.

CONCLUSIONS

The findings provide a preliminary indication that the phase angle between peak cortisol and DLMO is of interest as a potential biomarker for depression and therapeutic response. Adjunctive brexpiprazole may represent a strategy for correcting circadian dysfunction in patients with MDD and inadequate response to antidepressant treatment. ClinicalTrials.gov identifier: NCT01942733.

Exposure to Radiation During Work Shifts and Working at Night Act as Occupational Stressors Alter Redox and Inflammatory Markers

BACKGROUND

Studies of breast cancer etiology suggest evidence that night shift working and occupational exposure to ionizing radiation (IR) are defined risk factors for breast cancer development. There are few studies to clarify neuroendocrine and inflammatory status and the possible consequences particularly in occupational exposure.

AIM OF THE STUDY

Our aim was to associate the redox and inflammatory biomarkers with either nightshift working or occupational radiation exposure, and to compare their levels between the two groups at Alexandria University Hospitals, Alexandria, Egypt.

METHODS

We included 150 female nurses at Alexandria University Hospitals: 50 nightshift workers, 50 radiation workers, and 50 dayshift workers as a control group (neither work nightly nor radiation workers). In morning serum sample (7 am), we measured the concentrations of serum melatonin, Cortisol, tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ) by ELISA; malondialdehyde (MDA) and total antioxidant capacity (TAC) levels colorimetrically, and C-reactive protein (C-RP) levels by turbidimetric method.

RESULTS

Nightshift workers had significantly lower levels of melatonin and TAC, and higher levels of serum inflammatory markers and cortisol, than day shift control group of workers. Workers occupationally exposed to IR had significantly higher levels of serum melatonin, MDA and inflammatory markers, lower levels of serum cortisol, and lower TAC than day shift workers.

CONCLUSION

Occupational exposure to IR and working nightly alter circulating redox and inflammatory biomarkers.

Effect of High-Intensity Interval Training Versus Small-Sided Games Training on Sleep and Salivary Cortisol Level

PURPOSE

The authors compared sleep quality and salivary cortisol concentration after high-intensity interval training (HIIT) and small-sided games (SSGs) performed at the habitual training time in nonprofessional male soccer players.

METHODS

A total of 32 players (age = 24 [6] y, height = 1.77 [0.06] m, and body mass = 75 [12] kg) were randomized into an HIIT group or an SSG group. Actual sleep time, sleep efficiency (SE), sleep latency, immobility time (IT), moving time (MT), and fragmentation index were monitored using actigraphy before (PRE) and 2 nights after (POST 1 and POST 2) the training session. Salivary cortisol levels were measured before (PRE) and after (POST) training. Cortisol awakening response was evaluated.

RESULTS

Significant intragroup differences in the HIIT group were noted for actual sleep time (P < .0001), SE (P < .0001), sleep latency (P = .047), IT (P < .0001), MT (P < .0001), and fragmentation index (P < .0001) between PRE and POST 1 and for SE (P = .035), IT (P = .004), MT (P = .006), and fragmentation index (P = .048) between PRE and POST 2. Intergroup differences for actual sleep time (P = .014), SE (P = .048), IT (P < .0001), and MT (P = .046) were observed between the HIIT and the SSGs group at POST 1 were detected. Significant intragroup variations were observed in PRE and POST salivary cortisol levels (P < .0001 for HIIT; P = .0003 for SSGs) and cortisol awakening response (P < .0001 for HIIT; P < .0001 for SSGs). Significant intergroup differences between the HIIT and the SSGs group were found at POST (P < .0001) and in cortisol awakening response (P = .017).

CONCLUSIONS

Changes in actigraphy-based sleep parameters and salivary cortisol levels were greater after an acute session of HIIT than SSGs in this sample of nonprofessional male soccer players.

Attachment impacts cortisol awakening response in chronically depressed individuals

BACKGROUND

Early life experiences shape individual attachment, creating a template for regulating emotions in interpersonal situations, likely to persist across the lifespan. Research has shown that individual attachment creates vulnerability for depression, and also impacts the Hypothalamic-Pituitary-Adrenal (HPA) axis. Still, the relationship between attachment and the HPA axis in depressed individuals is unclear. Cortisol awakening response (CAR) has been recently investigated as a possibly useful physiological marker related to attachment insecurity and depression risk. However, research exploring the relationship between the CAR and attachment in individuals with chronic depression in either the presence or the absence of comorbid anxiety is lacking. The purpose of the current study was to fill this gap, by comparing the CAR in individuals with chronic depression with/without comorbid anxieties and controls. In addition, we also wanted to explore the relationship between attachment and the CAR in this group and to explore their predictive role for later depression severity.

METHODS

Individuals experiencing a current depressive episode at least six months in length (cMDD; n = 63) and healthy controls (HC; n = 57) were enrolled in the study (total n = 120). Participants completed a structured clinical diagnostic interview (SCID-I) as well as measures of depression severity (Beck Depression Inventory-II (BDI-II) and Hamilton Rating Scale for Depression) and attachment dimensions (Experiences in Close Relationships scale; ECR) at baseline. In addition, participants provided salivary samples at four time points (i.e. 0 (S1), 30, 45 and 60 min) following awakening on two consecutive days. S1 cortisol, the area under the curve with respect to ground (AUCg) and increase (AUCi) were calculated based on the average values across both days. The HC and cMDD groups were compared on all measures. The CAR for individuals with cMDD alone (n = 14) and individuals with cMDD with two or more comorbid anxiety disorders (cMDD ≥ 2Anx; n = 30) were also compared. A subset of participants (n = 59) agreed to return for follow up one year later. Participants returning for follow up repeated the BDI-II and ECR. No salivary samples were collected at follow-up.

RESULTS

The cMDD group had significantly lower S1 cortisol and AUCg compared to the HC group (both p ≤ 0.02). cMDD and cMDD ≥ 2Anx groups did not differ in their CAR. Regression analyses revealed that depression severity and the attachment interaction term was associated with lower S1 and AUCg cortisol (p < 0.01). Greater attachment avoidance was positively associated with S1 cortisol (p = 0.02), while mean awakening time on sample days was negatively associated with S1 cortisol. We also found a significant interaction between the attachment dimensions such that at low levels of attachment anxiety, attachment avoidance had a positive relationship with S1 cortisol and AUCg. The opposite relationship existed when attachment anxiety was high. Higher baseline BDI-II score and higher baseline attachment anxiety were predictive of higher scores on the BDI-II one-year later (both p < 0.05).

CONCLUSIONS

The current findings bring evidence that depression severity is associated with blunting of the CAR irrespective of the comorbid status with anxiety disorders. In addition, attachment avoidance may protect against the CAR blunting in individuals with low attachment anxiety. However, individuals with high attachment anxiety and avoidance might have additional CAR blunting. Attachment anxiety might be a good predictor of future depression severity.

Disaster-related prenatal maternal stress, and childhood HPA-axis regulation and anxiety: The QF2011 Queensland Flood Study

BACKGROUND

The fetal programming hypothesis suggests that prenatal maternal stress (PNMS) influences aspects of fetal development, such as the Hypothalamic Pituitary Adrenal (HPA) axis, enhancing susceptibility to emotional problems. No study (to our knowledge) has investigated this pathway considering development of preschool anxiety symptoms. Using data from the Queensland Flood study (QF2011), our objective was to determine whether toddler HPA-axis functioning mediated the association between aspects of flood-related PNMS and child anxiety symptoms at 4-years, and whether relationships were moderated by the timing of the stressor in utero or by the child's sex.

METHODS

Women, pregnant during the 2011 Queensland floods (N = 230), were recruited soon afterwards and completed questionnaires regarding their objective hardship (e.g., loss of personal property), subjective distress (post-traumatic-like symptoms) and cognitive appraisal of the disaster. At 16 months, indexes of the child's diurnal cortisol rhythm (awakening response, total daily output, diurnal slope [N = 80]), and stress reactivity (N = 111), were obtained. At 4-years, N = 117 mothers reported on their own mood and their children's anxiety symptoms; of these, N = 80 also had valid child cortisol reactivity data, and N = 64 had diurnal cortisol rhythm data.

RESULTS

A greater cortisol awakening response at 16 months mediated the relationship between subjective PNMS and anxiety symptoms at 4-years. Greater toddler daily cortisol secretion predicted more anxiety symptoms, independent of PNMS. The laboratory stressor did not elicit a cortisol response. PNMS effects were not dependent upon child sex nor on gestational timing of flood exposure.

CONCLUSIONS

Indexes of diurnal cortisol in toddlerhood may represent vulnerability for anxiety symptoms in preschoolers, both independent of, and following, exposure to disaster-related prenatal maternal subjective distress.

Exercising Caution Upon Waking-Can Exercise Reduce Sleep Inertia?

Sleep inertia, the transitional state of reduced alertness and impaired cognitive performance upon waking, is a safety risk for on-call personnel who can be required to perform critical tasks soon after waking. Sleep inertia countermeasures have previously been investigated; however, none have successfully dissipated sleep inertia within the first 15 min following waking. During this time, on-call personnel could already be driving, providing advice, or performing other safety-critical tasks. Exercise has not yet been investigated as a sleep inertia countermeasure but has the potential to stimulate the key physiological mechanisms that occur upon waking, including changes in cerebral blood flow, the cortisol awakening response, and increases in core body temperature. Here, we examine these physiological processes and hypothesize how exercise can stimulate them, positioning exercise as an effective sleep inertia countermeasure. We then propose key considerations for research investigating the efficacy of exercise as a sleep inertia countermeasure, including the need to determine the intensity and duration of exercise required to reduce sleep inertia, as well as testing the effectiveness of exercise across a range of conditions in which the severity of sleep inertia may vary. Finally, practical considerations are identified, including the recommendation that qualitative field-based research be conducted with on-call personnel to determine the potential constraints in utilizing exercise as a sleep inertia countermeasure in real-world scenarios.

Stress, the cortisol awakening response and cognitive function

There is evidence that stress-induced disruption of the circadian rhythm of cortisol secretion, has negative consequences for brain health. The cortisol awakening response (CAR) is the most prominent and dynamic aspect of this rhythm. It has complex regulatory mechanisms making it distinct from the rest of the cortisol circadian rhythm, and is frequently investigated as a biomarker of stress and potential intermediary between stress and impaired brain function. Despite this, the precise function of the CAR within the healthy cortisol circadian rhythm remains poorly understood. Cortisol is a powerful hormone known to influence cognition in multiple and complex ways. Studies of the CAR and cognitive function have used varied methodological approaches which have produced similarly varied findings. The present review considers the accumulating evidence linking stress, attenuation of the CAR and reduced cognitive function, and seeks to contextualize the many findings to study populations, cognitive measures, and CAR methodologies employed. Associations between the CAR and both memory and executive functions are discussed in relation to its potential role as a neuroendocrine time of day signal that synchronizes peripheral clocks throughout the brain to enable optimum function, and recommendations for future research are provided.

Morning and evening type: The cortisol awakening response in a sleep laboratory

BACKGROUND

Earlier evidence indicated an association between chronotype and the cortisol awakening response (CAR). However, these earlier data were collected without objective control for participant compliance being available, which, following recent guidelines, is considered critical for ensuring data validity. Here, we are seeking to replicate these earlier findings within a well-controlled sleep laboratory set up.

METHODS

The sample consisted of 103 young males, including 12 participants defined as 'evening' (MEQ < 41) and 20 participants defined as 'morning type' (MEQ > 59) types. All participants slept for one night in a sleep laboratory and were wakened at 6:30 AM the next morning. Saliva samples for the assessment of the CAR were collected under strict supervision at 0, 15, and 30 min post-awakening.

RESULTS

Significant effects of chronotype emerged consistently from both dimensional analyses across the entire sample and from comparisons between morning vs. evening type. Overall, greater morningness was associated with an increased cortisol level upon awakening (S1) as well as with a greater overall cortisol output (AUC_G), however, it was not associated with the CAR (AUC_I).

DISCUSSION

Our data corroborate earlier evidence by showing that, under well-controlled sleep-laboratory conditions, chronotype is related to an altered cortisol secretion over the post-awakening period with no association with the CAR. However, the results have to be replicated since it is only a single day study design.

Is Receiving Social Support Costly for Those Higher in Subjective Socioeconomic Status?

BACKGROUND

Although social support is generally thought to have positive consequences, this is not always the case. Receiving social support may threaten independence, which research has shown is more highly valued among those higher in socioeconomic status. As a result, support may be less strongly associated with positive outcomes for those higher in socioeconomic status (SES). Conversely, those lower in SES are more interdependent (Kraus, Piff, Mendoza-Denton, Rheinschmidt, & Keltner, 2012; Stephens, Markus, & Phillips, 2014) and may, therefore, be less threatened when receiving social support. This study examined SES as a moderator of how daily received support (within and between persons) predicted both daily psychological stressor appraisals and diurnal cortisol.

METHOD

Healthy undergraduate students (N = 128) participated in a 3-day study. Participants completed one or more evening diaries the first day of the study and additional questionnaires upon awakening, throughout the day, and at bedtime during the following 2 days. Support was measured each evening and stressor appraisals and cortisol were measured throughout the day.

RESULTS

As expected, for those who reported higher subjective SES, receiving more support than usual (within-person support) was associated with a flatter pattern of diurnal cortisol the next day. Although SES did not moderate the association of either within- or between-person support with stressor appraisals, the receipt of more support on average (between-person support) was associated with higher reported resources to cope.

CONCLUSION

The findings demonstrate that there may be physiological costs-but not psychological costs-associated with the receipt of support for those higher in socioeconomic status.

Mind-wandering content differentially translates from lab to daily life and relates to subjective stress experience

Experience and thoughts that are unrelated to the external surroundings are pervasive features of human cognition. Research under the rubric of mind-wandering suggests that such internal experience is context-dependent, and that the content of ongoing thought differentially influences a range of associated outcomes. However, evidence on how the extent of mind-wandering and its content translate from the laboratory to daily life settings is scarce. Furthermore, the relationship between such patterns of thought with markers of stress in daily life remains underexplored. In the current study, we examined multiple aspects of mind-wandering of ninety-three healthy participants (47 women, 25.4 ± 3.9 years) in both the laboratory and daily life and explored two questions: (a) how are mind-wandering extent and content correlated across both settings, and (b) what are their relationships with subjective stress and salivary cortisol levels in daily life? Our results suggest that the extent of off-task thinking is not correlated across contexts, while features of content—i.e., social, future-directed and negative thought content—robustly translate. We also found that daily life subjective stress was linked to more on-task, negative, and future-directed thinking, suggesting stress was linked with the need to act on personally relevant goals. Based on these results we speculate that differences in the links between stress and ongoing thought in daily life may be one reason why patterns of thinking vary from lab to everyday life. More generally, these findings underline the need to consider both context and content in investigating mind-wandering and associated features of subjective experience, and call for caution in generalizing laboratory findings to participants’ daily lives.

Age, Physical Activity Motivation and Perceived Stress in Minority Girls

BACKGROUND

Physical activity in childhood and adolescence helps support physical and emotional health.

PURPOSE

The study aimed to investigate if age was related to motivation for physical activity in minority girls, and whether the relationship may be potentially mediated by psychological or physiological stress.

METHODS

This cross-sectional observational study recruited Latino and African American girls ages 8 - 12 years (n = 79) in Tanner stage 1 or 2 via purposive sampling. Intrinsic motivation and perceived stress were measured by self-report survey; morning salivary cortisol samples were taken to calculate cortisol awakening response to estimate biological stress reactivity.

RESULTS

Increased age was related to higher intrinsic motivation to engage in physical activity. Lower perceived stress and lower awakening cortisol response were associated with higher intrinsic motivation. Bootstrapped mediation results indicated perceived stress may be a pathway through which age impacts intrinsic motivation for physical activity.

CONCLUSION

While motivation to engage in physical activity may increase with age, perceived stress may dampen this motivation, resulting in decreased physical activity. Interventions to help increase pre-adolescent girls' engagement in active behaviors may benefit from reducing children's perceptions of stress.

The effects of post-awakening light exposure on the cortisol awakening response in healthy male individuals

BACKGROUND

It is assumed that the expression of the cortisol awakening response (CAR) is modulated by light exposure during the peri-awakening period. While initial evidence supports this principal effect, the specific role of the spectral composition of light (brightness and wavelength) is still incompletely understood.

METHOD

Two counterbalanced within-subject experiments were conducted in a standardized sleep laboratory setting to investigate the effect of light intensity (study I; two days: dim vs. bright light) and spectral composition (study II; three days: red vs. blue vs. green light) on the CAR. Across studies, light exposure was conducted for one-hour post-awakening and the accuracy of CAR assessments (based on eight saliva samples) was well-controlled in line with recent guidelines.

RESULTS

The two studies revealed consistent effects of light exposure on the CAR. Specifically, an increased CAR was found after exposure to bright (vs. dim) light (study I; (F_{(3.7, 106.4)} = 11.93, p < .001, η²_p = .29) and following blue and green (vs. red) light exposure (study II; F_{(4.9, 194.6)} = 2.49, p = .037, η²_p = .10).

CONCLUSION

Our findings illustrate the crucial role of light intensity and wavelength for expression of the CAR, in line with current theoretical knowledge of underlying neurobiological mechanisms.

The cortisol awakening response (CAR) interacts with acute interpersonal stress to prospectively predict depressive symptoms among early adolescent girls

The cortisol awakening response (CAR) has been shown to prospectively predict depression, but it remains unresolved whether a greater CAR predicts risk independently of subsequent acute stress, or whether greater CAR indicates increased vulnerability to subsequent acute stress. Further, no prior work has evaluated whether the CAR increases vulnerability to certain types of acute stress, but not others, in predicting depression. To address these gaps, we investigated whether the CAR predicted depressive symptoms alone and in interaction with acute interpersonal stress in a one-year longitudinal study of 86 early adolescent girls with no history of diagnosable depression. To index the CAR, adolescents collected saliva at waking and 30-minutes past waking for 3 days; compliance with the sampling protocol was electronically monitored. Diagnostic and objective contextual stress interviews were used to quantify acute stress in the 2-months prior to worst depressive symptom onset during the follow-up. Supporting hypotheses, results indicated that greater CAR predicted greater depressive symptoms, and interacted with acute interpersonal stress in predicting depressive symptoms. Further, the CAR interacted with acute dependent (i.e., at least partially arising from the person's behavior) interpersonal stress in predicting depressive symptoms. In contrast, the CAR did not interact with acute non-interpersonal stress nor acute interpersonal independent (i.e., fateful) stress in predicting depressive symptoms. These results further refine circumstances in which the CAR is predictive of depressive symptoms among early adolescent girls, and highlight the importance of focusing on etiologically relevant stress when testing interactions between physiological stress indicators and environmental stress.

Tomorrow's gonna suck: Today's stress anticipation predicts tomorrow's post-awakening cortisol increase

The cortisol awakening response (a rapid rise in cortisol concentration shortly after awakening) is hypothesized to prepare the organism to cope with upcoming demands, suggesting a key role for anticipatory stress in its regulation. Yet, no thorough test of this hypothesis incorporating temporal dynamics of the underlying processes has been conducted so far. To address this gap in the literature, the present study investigated the effects of anticipated stress for the next day (assessed in the evening) on an estimate of the cortisol awakening response (assessed in the following morning). In an ambulatory assessment paradigm, 42 participants (69% female; mean age = 22.8, range = 18-30 years) completed 5 consecutive days of assessments in their daily lives, collecting saliva samples at awakening and 30 min later. Using hierarchical linear modeling, associations with anticipatory stress were examined separately on the within- and between-person level. In line with our expectations, anticipatory stress predicted the post-awakening cortisol increase on the within-person level, implying an elevated cortisol rise on days for which more stress than usual had been anticipated. In contrast, on the between-person level higher average anticipatory stress did not predict an increased cortisol rise. Taken together, the findings confirm a key role of anticipatory stress in the regulation of the cortisol awakening response on the within-person level.

Cortisol awakening response in children and adolescents with autism spectrum disorder: a systematic review and meta-analysis

BACKGROUND

The cortisol awakening response (CAR) is characterised by an increase in cortisol in the 30 to 60 min after waking. Research has found significant associations between an atypical CAR and symptoms of stress and anxiety in typically developing (TD) children and adolescents. A number of studies have explored the CAR in autism spectrum disorder (ASD), but no evidence synthesis is available to date.

OBJECTIVE AND METHODS

Based on a preregistered protocol (PROSPERO: CRD42017051187), we carried out a systematic review (SR) and meta-analysis (MA) of CAR studies to explore potential significant differences between children and adolescents with ASD and TD controls. Web of Science, PubMed and PsychInfo were searched until January 2019. A random-effects model was used to pool studies and we used the Newcastle-Ottawa scale (NOS) to assess study quality and risk of bias.

FINDINGS

The SR retrieved a total of nine studies, with mixed findings on the comparison of the CAR between children and adolescents with ASD and TD controls. The MA, based on four studies (ASD; n=117 and TD n=118), suggested no differences between the CAR in ASD and TD populations (SMD: -0.21, 95% CI -0.49 to 0.08). In terms of NOS items, no study specified Representativeness of the cases and Non-response rate. DISCUSSION AND CLINICAL IMPLICATIONS: Given the relatively few studies and lack of appropriately matched TD controls, additional research is needed to further understand and recommend the utility of the CAR as a reliable marker to differentiate ASD and TD.

The influence of mindfulness and social support on stress reactivity during pregnancy

Exaggerated stress reactivity can lead to negative health outcomes, which can be especially harmful during important periods of development such as pregnancy. Therefore, studies are needed to examine potential protective factors associated with lower perceived stress reactivity and lower cortisol awakening response (CAR) during pregnancy. The current cross-sectional study examined whether low-income women (n = 152) with higher mindfulness (attentiveness and awareness of the present moment) and more perceived social support had lower levels of perceived stress reactivity and a lower CAR during pregnancy. Women completed self-report measures of mindfulness (Mindful Attention Awareness Scale), social support (Medical Outcomes Study-Social Support Scale), and perceived stress reactivity (Perceived Stress Reactivity Scale) during their first trimester of pregnancy and collected saliva using the passive drool procedure at home (at awakening and at 30 min after awakening). Results showed that women with greater mindfulness and greater perceived social support had significantly lower perceived stress reactivity, but not a lower CAR. These results provide preliminary support for mindfulness and social support as potential protective factors of perceived stress reactivity and have implications for experimental studies aimed at improving pregnant women's mindfulness and social support for reducing their stress reactivity and potentially improving health outcomes.

Effects of Nocturnal Sleep Quality on Diurnal Cortisol Profiles and Attention in Nurses: A Cross-Sectional Study

Objective:

Low sleep quality (LSQ) activates the hypothalamic–pituitary–adrenal (HPA) axis and is related to arousal. Nursing staff, who work in shifts, tend to exhibit LSQ, which affects the level of vigor after awakening. This study investigated the effects of nocturnal sleep quality on diurnal cortisol profiles and sustained attention in day-shift nurses.

Method:

This study adopted a prospective cross-sectional design. Participants were recruited from a university-affiliated hospital in northern Taiwan. In the initial stage of this study, the Chinese Pittsburgh Sleep Quality Index (PSQI) Questionnaire was administered to 199 participants to categorize them as either LSQ (PSQI > 5) or high sleep quality (HSQ; PSQI ≤ 5). Participants were then randomly sampled from the two groups. Nocturnal sleep data and four diurnal saliva samples were collected for each participant. Sustained attention was measured before they started work. A total of 32 and 29 participants in the HSQ and LSQ groups, respectively, completed the data collection process.

Results:

Compared with the HSQ group, the LSQ group exhibited earlier wake-up times ( p = .02), a flatter cortisol awakening response (CAR) slope ( p < .01), a flatter morning-to-evening slope ( p < .01), and prolonged reaction speed and mean reaction time before starting work ( p < .01).

Conclusion:

Compared with the HSQ group, the LSQ group exhibited impaired HPA-axis regulation, with a flatter CAR and diurnal cortisol slope and poor sustained attention in the morning. Nursing staff are advised to achieve HSQ to improve attention and performance levels and maintain optimum work safety.

Investigating associations between momentary stress and cortisol in daily life: What have we learned so far?

Since cortisol measurement in saliva has been established, it has been used as an indicator of stress-related hypothalamic-pituitary-adrenocortical axis activity. Concurrent development of methodological frameworks such as ambulatory assessment, ecological momentary assessment, and experience sampling have provided opportunities to combine both approaches in daily life research. The current review provides a summary of basic methodological principles and recommendations, as well as abstracts of findings of studies investigating momentary associations between stress and cortisol in daily life with an emphasis on within-subject associations (i.e. average covariance in repeated momentary assessments of stress and cortisol, and individual-specific deviations from the average covariance). Methodological challenges related to stress measurement, sampling principles, and appropriate statistical modeling are discussed, followed by a description of the historical development of studies on within-subject associations between momentary daily life stress and cortisol. The review concludes with a discussion of controversial methodological characteristics of these studies regarding operationalizations of stress, compliance, timing and frequency of stress and cortisol sampling, and reporting of effect sizes. Future research in this area would benefit from automated cortisol assessment, broadening of the scope of stress response measures, use of advanced statistical models that better account for dynamics in the stress process in daily life, and attempts to replicate findings. While previous studies of momentary stress and concurrent cortisol assessments have reliably confirmed some fundamental predictions from stress theory in daily life, future studies should aim at providing progress by testing innovative research questions and utilizing new technological developments.

Dehydroepiandrosterone and cortisol as markers of HPA axis dysregulation in women with low sexual desire

Previous research has found lower serum levels of dehydroepiandrosterone (DHEA) or its sulfated form, DHEA-S, in women diagnosed with Hypoactive Sexual Desire Disorder (HSDD). Given that DHEA and DHEA-S have multiple direct actions on the brain as well as anti-glucocorticoid properties, it is possible that lower levels of DHEA directly impact women's sexual functioning. To date, the significance of the lower DHEA levels remains unclear. To our knowledge, there has been no empirical study of stress hormones as markers of HPA dysregulation in women with HSDD. To attend to this gap, the present study utilized several measures of HPA axis function - morning and evening cortisol and DHEA, the cortisol awakening response (CAR), diurnal cortisol slope, and cortisol:DHEA ratio - and examined their relationship with sexual functioning in N = 275 women with (n = 137) and without (n = 138) HSDD. Results demonstrated multiple hormonal markers of HPA dysregulation in women diagnosed with HSDD compared to control participants, specifically, lower AM cortisol and AM DHEA levels, a flatter diurnal cortisol slope, and a lower CAR. Overall, results of the present study indicate that persistently low sexual desire in women is associated with HPA axis dysregulation, with both cortisol and DHEA alterations potentially detrimental to sexual desire.

Socioeconomic status disparities affect children's anxiety and stress-sensitive cortisol awakening response through parental anxiety

Socioeconomic status (SES) disparities have profound impacts on child development and health, which are linked to negative emotions and alterations in the integrity of stress-sensitive hypothalamus-pituitary-adrenal (HPA)-axis system. However, its underlying psychophysiological mechanisms remain poorly understood. Here we investigate how family SES, in concert with parental anxiety, affects children's anxiety and their integrity of HPA-axis system in two studies involving a total of 1318 children and their parents. In Study 1 with a cohort of 1088 children and their parents, we found that low-SES children relative to high-SES ones experienced a higher level of anxiety mediated by increasing parental anxiety. In Study 2 with an independent cohort of 230 children and their parents, we found that low-SES children exhibited an increase in pre-bedtime basal cortisol but a decrease in cortisol awakening response (CAR). Structural equation modeling (SEM) further revealed that the association between low SES and children's reduced CAR was mediated by increased parental and child anxiety. Our findings suggest that low-SES children are more vulnerable to anxiety and altered HPA-axis integrity, most likely mediated through increased parental anxiety.

The relationship between salivary cortisol and perinatal depression in women undergoing termination of pregnancy for fetal anomaly: A prospective cohort study

BACKGROUND

The hypothalamic-pituitary-adrenal axis plays a crucial role in the neurobiological pathways for depression. The aim of this study was to determine the relationship between salivary cortisol and depression in women before and after termination of pregnancy due to fetal anomaly.

STUDY DESIGN

A prospective cohort study was conducted. One-way ANOVA and linear correlation were conducted to analyse the relationship between salivary cortisol and depression before and after termination of pregnancy.

RESULTS

No significant difference in morning and evening cortisol levels between women underwent TOP for fetal anomaly without depression and those with depression, but the women underwent TOP for fetal anomaly had significantly higher levels of morning and evening cortisol than women with healthy pregnancy. Cortisol awakening response was lower in women underwent termination of pregnancy, than in women with normal pregnancy; lower in women underwent termination of pregnancy with depression than in those women without depression. Cortisol awakening response also had a negative correlation with depression, and the correlation coefficients for cortisol awakening response and depression after TOP (R = 0.461) were higher than the correlation coefficients for cortisol awakening response and depression before TOP(R = 0.238).

CONCLUSIONS

Our results were not only useful to support the hypothesis that hypothalamic-pituitary-adrenal axis functioning would turn hypoactive, with depression progressing to increase in severity, but also helpful with insights into the predictive effects of cortisol awakening response in depression after TOP. We suggest that further research should be conducted on the relationship between salivary cortisol and depression before and after TOP for fetal anomaly.

Relative sensitivity of cortisol indices to psychosocial and physical health factors

OBJECTIVE

Regulation of cortisol under resting conditions is widely used to assess physical and psychological status, but due to the diversity of possible assessments (e.g., cumulative levels; diurnal patterns), considering one or a few at a time hampers understanding and interpretation. Moreover, most studies of cortisol regulation focus on negatively-valanced experiences. This study examined the inter-correlations among cortisol indices and their relative contribution to the explained variance in diverse psychosocial and health factors, including positive functioning.

METHODS

Data are from midlife and older adults (N = 513; 47.2% male). Cortisol was assessed in urine (overnight) and saliva (at rest and over 4 consecutive days). Positive and negative psychosocial and health factors were assessed by self-report. In addition to examining associations among cortisol indices, relative weight analysis was used to determine which indices were most robustly linked to specific psychosocial factors.

RESULTS

Inter-correlations among indices were weak-to-moderate, suggesting that they measure different aspects of hypothalamic-pituitary-axis activity. Overall variance in psychosocial and health factors (R2) explained by the cortisol indices ranged from 0.01 to 0.07. Of this explained variance, relative weight analysis showed that waking cortisol contributed most to the variance in hedonic well-being (32.1%-38.2%), bedtime cortisol to depression-related factors (32.1%-46.9%), the cortisol awakening response to eudaimonic well-being (35.8%-50.5%), cortisol slope to perceived stress (29.2%), and urinary cortisol to physical factors (38.5% and 62.7%).

CONCLUSIONS

Positive and negative factors were related to largely non-overlapping cortisol indices. This study illuminates nuanced associations among cortisol indices and diverse aspects of mental and physical health, facilitating thoughtful examination of the complex role of hypothalamic-pituitary-axis activity in health.

Chronic stress exposure, diurnal cortisol slope, and implications for mood and fatigue: Moderation by multilocus HPA-Axis genetic variation

Chronic stress exposure has been shown to alter hypothalamic-pituitary-adrenal (HPA) axis functioning, which may mediate its effects on psychopathology and negative health outcomes. The nature of the chronic stress-HPA axis dysregulation is unclear and individuals likely vary in the extent to and manner in which indices of HPA axis regulation, such as diurnal cortisol slope, are influenced by chronic stress. We examined whether HPA-axis-linked genetic variation moderates the association between chronic stress and diurnal cortisol slope, and potential implications for mood and fatigue (possible manifestations of negative clinical outcomes). 211 adolescents (M age 15.89, 54.5% female) completed chronic stress interviews and provided DNA samples. Participants then provided saliva samples at waking and 12 h post-waking for two consecutive weekdays. HPA-axis genetic variation was calculated using a multilocus genetic profile score (MGPS) approach, using ten SNPs from CRHR1, NR3C1, NR3C2, and FKBP5 to generate an additive score of HPA-axis-linked genetic risk. Neither chronic stress nor MGPS directly predicted diurnal slope, but MGPS moderated the association between chronic stress and diurnal slope, with stress predicting a high waking cortisol followed by steep slope among youth with low but not high MGPS scores. MGPS also interacted with chronic stress to predict both negative affect and fatigue, and moderated the indirect effect of chronic stress on mood and fatigue via diurnal slope. Results suggest that diurnal cortisol regulation may be one mechanism by which genetic risk intensifies the association between chronic stress and negative outcomes.

Maternal circadian cortisol mediates the link between prenatal distress and breastfeeding

Breastfeeding is associated with positive maternal and infant outcomes. It is recommended that women exclusively breastfeed for the first 6 months postpartum; however, these recommendations are not met in the majority of women. Psychological distress in pregnancy is associated with lower rates of breastfeeding initiation and duration in the postpartum period. The mechanisms linking maternal distress to breastfeeding are not understood. In this study we examined maternal circadian cortisol as a mechanism linking distress in pregnancy to breastfeeding. This study is a secondary data analysis of 197 pregnant women with singleton pregnancies who were part of a larger study of the effects of maternal mood on fetal and infant development. About 34% of women reported exclusively breastfeeding, 18% reported exclusively formula feeding, and 48% reported mixed feeding. Participants reported on perceived stress, perinatal anxiety and depression, and socioeconomic status during pregnancy. They provided salivary cortisol samples at three times a day for 3 days at 24, 30, and 36 weeks' gestation. Participants who reported lower socioeconomic status in pregnancy were less likely to breastfeed, and lower maternal cortisol awakening responses mediated this association. This area of research may identify foci in the prenatal period that could serve as targets for interventions to increase rates of breastfeeding. Lay summary Pregnant women who reported lower socioeconomic status in pregnancy were less likely to breastfeed. This association was mediated by lower cortisol awakening responses, but not evening cortisol levels, over pregnancy.

Inter-correlations Among Clinical, Metabolic, and Biochemical Parameters and Their Predictive Value in Healthy and Overtrained Male Athletes: The EROS-CORRELATIONS Study

Objectives: The Endocrine and Metabolic Responses on Overtraining Syndrome (EROS) study identified multiple hormonal and metabolic conditioning processes in athletes, and underlying mechanisms and biomarkers of overtraining syndrome (OTS). The present study's objective was to reveal independent predictors and linear correlations among the parameters evaluated in the EROS study to predict clinical, metabolic, and biochemical behaviors in healthy and OTS-affected male athletes. Methods: We used multivariate linear regression and linear correlation to analyze possible combinations of the 38 parameters evaluated in the EROS study that revealed significant differences between healthy and OTS-affected athletes. Results: The testosterone-to-estradiol (T:E) ratio predicted the measured-to-predicted basal metabolic rate (BMR) ratio; the T:E ratio and total testosterone level were inversely predicted by fat mass and estradiol was not predicted by any of the non-modifiable parameters. Early and late growth hormone, cortisol, and prolactin responses to an insulin tolerance test (ITT) were strongly correlated. Hormonal responses to the ITT were positively correlated with fat oxidation, predicted-to-measured BMR ratio, muscle mass, and vigor, and inversely correlated with fat mass and fatigue. Salivary cortisol 30 min after awakening and the T:E ratio were inversely correlated with fatigue. Tension was inversely correlated with libido and directly correlated with body fat. The predicted-to-measured BMR ratio was correlated with muscle mass and body water, while fat oxidation was directly correlated with muscle mass and inversely correlated with fat mass. Muscle mass was directly correlated with body water, and extracellular water was directly correlated with body fat and inversely correlated with body water and muscle mass. Conclusions: Hypothalamic-pituitary responses to stimulation were diffuse and indistinguishable between the different axes. A late hormonal response to stimulation, increased cortisol after awakening, and the T:E ratio were correlated with vigor and fatigue. The T:E ratio was also correlated with body metabolism and composition, testosterone was predicted by fat mass, and estradiol predicted anger. Hydration status was inversely correlated with edema, and inter-correlations were found among fat oxidation, hydration, and body fat.

Comparing stress and arousal systems in response to different social contexts in children with ASD

Response to psychological stress can vary based on the extent to which the context is perceived as stressful, especially under different social conditions. The purpose of this preliminary study was to compare physiological stress (cortisol) and regulation (respiratory sinus arrhythmia, RSA) of 10-12 year old children with autism spectrum disorder (ASD, n = 31) or typical development (TD, n = 25) when exposed to two social stress protocols. The extent to which perceived emotion (affect recognition) and anxiety (state and trait) mediate the stress response was also explored. Results revealed different patterns of stress responses dependent on the type of stressor. During a friendly social interaction, both groups generally showed an adaptive, synergistic response between cortisol and RSA. In response to social evaluation, however, the ASD group did not show correlating responses between physiological systems, which was likely due to a blunted stress response to the social evaluative stressor. The ability to recognize neutral faces mediated the relationship between diagnostic group and physiological response to social evaluation, indicating that perception of threat is essential to triggering a stress response. The current study emphasizes the need to consider the important role of social context, social perception, and perceived anxiety when examining social interaction and stress.

Correlations between changes in the hypothalamic-pituitary-adrenal axis and neurochemistry of the anterior cingulate gyrus in postpartum depression

BACKGROUND

This study aimed to investigate associations between indicators of hypothalamic-pituitary-adrenal axis (HPA) functioning and metabolite levels in the anterior cingulate gyrus (ACG) of women with postpartum depression (PPD).

METHODS

The sample (mean age = 28.5 ± 4.6 years) consisted of 20 women with PPD and 19 postpartum euthymic (PPE) women. Brain metabolites were quantified by proton magnetic resonance spectroscopy (¹H-MRS). Salivary cortisol samples were collected upon awakening and 30 min and 12 h later, at 20.6 ± 6.6 (PPD) and 23.0 ± 7.4 (PPE) weeks after childbirth.

RESULTS

There were no significant differences between groups in respect to metabolite levels in the ACG. Compared with PPE, PPD women had less diurnal variation (DVr%). In the PPD group, positive correlations were found between DVr% and myo-inositol (mI/Cr) levels, and between cortisol awakening response (CARi%) and glutamate + glutamine (Glx/Cr) levels. The correlation between CARi% and Glx/Cr remained significant even after controlling for the interval, in weeks, from birth and MR spectroscopy and to hormonal data collection, and the use of contraceptives.

LIMITATIONS

The limitations of the study include the small sample size and the use of oral contraceptives by around half of the sample.

CONCLUSIONS

In the remote postpartum period (mean 21.8 ± 6.9 weeks) and in the presence of depressive episodes, the decreased responsiveness of the HPA axis after awakening and a smaller decrease in cortisol levels over the day were associated with lower levels of metabolites in the ACG. These results may contribute to the development of biological models to explain the etiology of PPD.

Exploring the multidimensional complex systems structure of the stress response and its relation to health and sleep outcomes

To gain a comprehensive understanding of the multidimensional complex systems structure of the stress response and related health outcomes, we utilized network analysis in a sample of 328 healthy participants in two steps. In a first step, we focused on associations between measures of basal hypothalamic-pituitary-adrenal axis functioning and subjective stress perceptions. In a second step, we linked these diverse stress-related measures to biomarkers and self-reports of health and sleep. Overall, measures clustered depending on their method of assessment, with high correlations between different saliva-based indices of diurnal cortisol regulation, between cortisol and cortisone levels in hair, between different biological health indicators (systemic inflammatory activity and body mass index), between state (experience sampling) and trait (questionnaire-based) self-reports of stress and wellbeing, and between different self-reports of sleep. Bridges between clusters suggested that if individuals perceive stress throughout their daily lives this is reflected in their total salivary cortisol output possibly contributing to long-term cortisol accumulation in hair. Likewise, earlier awakening time may contribute to cortisol accumulation in hair via an influence on awakening cortisol processes. Our results show that while meaningful connections between measures exist, stress is a highly complex construct composed of numerous aspects. We argue that network analysis is an integrative statistical approach to address the multidimensionality of the stress response and its effects on the brain and body. This may help uncover pathways to stress-related disease and serve to identify starting points for prevention and therapeutic intervention.

Morning Cortisol Is Associated With Stress and Sleep in Elite Military Men: A Brief Report

INTRODUCTION

Accumulating evidence suggests that trends in salivary cortisol after awakening may be reliable biological predictors of morbidity and mortality. In a sample of elite military men, our lab recently established summary parameters of morning cortisol as well as their stability across 2 d of repeated sampling.

MATERIALS AND METHODS

In this follow-on study, we evaluated summary parameters and their relationships to theoretically relevant demographic (i.e., age, body mass index) and biobehavioral correlates (i.e., blood pressure [BP], sleep parameters, fatigue, and perceived stress). Fifty-eight male active duty U.S. Navy SEALs self-collected salivary samples on 2 consecutive, midweek workdays upon waking (WAKE), WAKE+30 min, WAKE+60 min, 4 p.m., and 9 p.m. in a nondeployed, free-living setting. Resting BP was measured manually, and sleep-wake periods were objectively derived using actigraphy. Daily fatigue and perceived stress were measured by self-report. Summary parameters of morning cortisol magnitude (i.e., peak value [Peak], area under the curve in terms of ground [AUCG], and average of morning samples [AVE]) were assessed with respect to each demographic and biobehavioral item via correlational analyses. A subgroup of 29 participants was selected for compliance with salivary sampling in the morning across 2 d.

RESULTS

Perceived stress was positively associated with Peak (r[27] = 0.437, p < 0.05), AUCG (r[25] = 0.500, p < 0.01), and AVE (r[25] = 0.506, p < 0.01). Total sleep time was also positively associated with Peak (r[26] = 0.378, p < 0.05). There were borderline associations between some summary parameters and diastolic BP, percent sleep, and wake after sleep onset. Age, systolic BP, body mass index, time in bed, sleep efficiency, and fatigue did not associate with morning cortisol.

CONCLUSIONS

Preliminary evidence of morning cortisol summary parameters as biobehavioral indicators was established, and these parameters appeared to associate with stress and sleep in elite military men.

Cortisol response to awakening in prepubertal children and adults: Magnitude and variability

Within the first 30-45 min after awakening, there is a characteristic rise in cortisol that is referred to as cortisol awakening response (CAR). Over the past decades, the CAR has become an important biomarker, mainly because of its reported association with health and disease. Previous research showed that the CAR can already be reliably assessed in infants and children. Yet, earlier findings on the influence of age have been inconsistent, and limited attention has been devoted to prepubertal children. Here, we aimed to contrast the magnitude and stability of the CAR in prepubertal children and adults. To this end, 24 healthy adults between 35 and 50 years of age and 24 healthy children between 6 and 9 years of age collected four salivary cortisol samples within 45 min after awakening on 4 separate days, 2 weekdays, and 2 weekend days. Our results showed that there was a marked CAR on weekdays and weekend days in both adults and children. In children, however, the CAR was overall significantly attenuated relative to adults. Moreover, while the cortisol increases after awakening were, both on weekdays and weekend days, highly correlated in adults, there were no such associations in children. Together, these data suggest that the CAR is less pronounced and less stable in prepubertal children compared to adults. Such age differences need to be taken into account when using the CAR as a biomarker in clinical settings.

Childhood adversity moderates the influence of proximal episodic stress on the cortisol awakening response and depressive symptoms in adolescents

Childhood adversity (CA) is known to predict sensitization to proximal stressors. Researchers have suggested that disruptions in hypothalamus-pituitary-adrenal axis functioning may be a biological mechanism. If so, CA may predict altered associations between proximal life stress and markers of cortisol secretion. We examined whether CA moderates associations between recent episodic stress and (a) the cortisol awakening response (CAR), and (b) depressive symptoms, in 241 adolescents aged 14-17 years (cortisol n = 196). Salivary cortisol was sampled at 0, 30, and 60 min postawakening for 2 days. The CAR was calculated as the area under the curve with respect to increase and waking cortisol. CA and episodic stress were assessed using contextual-threat-method-coded objective interviews. CA significantly interacted with episodic stress to predict both the CAR and depression. Among those with low CA, episodic stress predicted increased CAR but did not predict depression. For adolescents with high CA, episodic stress predicted lower CAR and higher depression. These interactions were found only for independent (uncontrollable, fateful) events, and not for dependent (self-generated) stress. Increased allostatic load resulting from CA exposure may interfere with adolescents' ability to optimally regulate their CAR in relation to recent stress, contributing to increased depression risk.

Temporomandibular Disorders Related to Stress and HPA-Axis Regulation

Temporomandibular disorders (TMDs) are characterized by pain and dysfunction in the masticatory apparatus and the temporomandibular joint (TMJ). Previous trauma, stress symptoms, psychosocial impairment, and catastrophizing have been related to TMD. To assess if the hypothalamic-pituitary-adrenal (HPA) axis is upregulated in TMD patients, we performed a cross-sectional study with saliva from 44 TMD patients and 44 healthy sex- and age-matched controls for cortisol (F) and cortisone (E) with liquid chromatography-tandem mass spectrometry. Furthermore, we calculated the F/E ratio for the evaluation of 11β-hydroxysteroid dehydrogenase activity. We also assessed anxiety/depression and pain catastrophizing scores from a questionnaire that participants completed prior to the examination. We found that F (P=0.01), E (P=0.04), the F/E ratio (P=0.002), and the sum of glucocorticoids (E + E) in saliva (P=0.02) were significantly higher in the TMD group. Anxiety/depression and catastrophizing scores were also significantly higher in the TMD group (P < 0.0001). Our findings indicate that patients with TMDs may have an upregulated HPA axis with higher F secretion from the adrenal cortex. Anxiety/depression and pain catastrophizing scores were significantly higher in the TMD group, and psychological factors may contribute to chronic upregulation of the HPA axis.

Fear of pain and cortisol reactivity predict the strength of stress-induced hypoalgesia

Background

Acute stress can have an effect on pain sensitivity, yet the direction of the effect – whether it is hypoalgesic or hyperalgesic – is mixed across studies. Moreover, which part of the stress response influences pain sensitivity is still unclear. In the current experimental study, we aim to examine the effect of acute stress on heat pain thresholds and pain tolerance levels in healthy participants, while taking into account individual differences in stress responses.

Methods

Forty‐two healthy participants were randomly assigned to either a well‐validated stress paradigm: the Maastricht Acute Stress Task (MAST; combining physical and psychological stressors) or to a nonstressful version of the task. Heat pain thresholds and tolerance levels were assessed at three times: prior to the MAST, immediately after the MAST during the presumed sympatho‐adrenal medullary (SAM) response, and 15 min after MAST to cover the presumed hypothalamus–pituitary–adrenal (HPA) axis response. Stress responses were assessed both subjectively and physiologically.

Results

We observed that the acute stress induction led to increased heat pain thresholds, an effect that was present only in participants showing a cortisol response following stress induction and only in the presumed HPA axis time window. The strength of this hypoalgesic effect was further predicted by the change in cortisol and by fear of pain levels.

Conclusions

Our findings indicate that the HPA axis – and not the autonomic – stress response specifically underlies this stress‐induced hypoalgesic effect, having important implications for clinical states with HPA axis dysfunctions.

Significance

This experimental study shows that an acute stress induction – that combines physical and psychological stressors – increases heat pain thresholds, but not tolerance in healthy participants. Furthermore, the magnitude of this stress‐induced hypoalgesic effect is predicted by cortisol reactivity and fear of pain, revealing specific involvement of the HPA axis stress system and interactions with pain‐related psychosocial aspects.

Glucocorticoid hormones are both a major circadian signal and major stress signal: How this shared signal contributes to a dynamic relationship between the circadian and stress systems

Glucocorticoid hormones are a powerful mammalian systemic hormonal signal that exerts regulatory effects on almost every cell and system of the body. Glucocorticoids act in a circadian and stress-directed manner to aid in adaptation to an ever-changing environment. Circadian glucocorticoid secretion provides for a daily waxing and waning influence on target cell function. In addition, the daily circadian peak of glucocorticoid secretion serves as a timing signal that helps entrain intrinsic molecular clock phase in tissue cells distributed throughout the body. Stress-induced glucocorticoid secretion also modulates the state of these same cells in response to both physiological and psychological stressors. We review the strong functional interrelationships between glucocorticoids and the circadian system, and discuss how these interactions optimize the appropriate cellular and systems response to stress throughout the day. We also discuss clinical implications of this dual aspect of glucocorticoid signaling, especially for conditions of circadian and HPA axis dysregulation.

Salivary cortisol and alpha-amylase diurnal profiles and stress reactivity in children with Attention Deficit Hyperactivity Disorder

There is growing evidence for dysregulation of the stress system in individuals with Attention Deficit Hyperactivity Disorder (ADHD). The stress system includes neuroanatomical and functional components that function in concert to maintain homeostasis and its main effectors are the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic/adrenomedullary nervous system (SNS). As stress system activity demonstrates a distinct circadian variation, we aimed to describe simultaneously, diurnal rhythms of both the HPA axis and the SNS in children with ADHD and a comparison group. Moreover, we attempted to investigate stress responses to a physical stressor, venipuncture, in both groups. Sixty-two prepubertal children with ADHD combined (ADHD-C) or inattentive (ADHD-I) type and 40 typically developing children provided saliva samples at six specific time points during a day, as well as before and 10 min after a scheduled morning venipuncture. Salivary cortisol and α- amylase were selected as reliable noninvasive biomarkers for HPA axis and SNS function and were measured in the samples obtained. Results revealed that children with ADHD-C had lower mean cortisol values both 30 min after awakening and at 18:00 h than controls (p = 0.002 and p = 0.018 respectively), as well as lower mean Cortisol Awakening Response (CAR) and Area Under the Curve for "wake to bed" period (AUC_i) values of cortisol (p = 0.004 and p = 0.001, respectively). Also, mean CAR and cortisol AUC_i were lower in children with ADHD-I than the control group (p = 0.034 and p = 0.038 respectively). Alpha-amylase measurements showed an increase over time (p < 0.001), which was similar in all three groups. Interestingly, α-amylase changes over time were correlated with the corresponding cortisol changes (p < 0.001). Venipuncture, elicited a significant increase only in α-amylase levels and more so in the control group (p = 0.003). These findings suggest a partial hypofunction of the stress system in children with ADHD.

Salivary Cortisol Profiles of Children with Hearing Loss

OBJECTIVES

It has long been speculated that effortful listening places children with hearing loss at risk for fatigue. School-age children with hearing loss experiencing cumulative stress and listening fatigue on a daily basis might undergo dysregulation of hypothalamic-pituitary-adrenal (HPA) axis activity resulting in elevated or flattened cortisol profiles. The purpose of this study was to examine whether school-age children with hearing loss show different diurnal salivary cortisol patterns than children with normal hearing.

DESIGN

Participants included 32 children with mild to moderate hearing loss (14 males; 18 females) and 28 children with normal hearing (19 males; 9 females) ranging in age from 6 to 12 years. Saliva samples were obtained six times per day on two separate school days. Cortisol levels were measured by mass spectrometric detection after liquid-liquid extraction. Salivary cortisol levels between children with hearing loss and children with no hearing loss over the course of the day were examined with hierarchical linear modeling using mixed model statistical analysis. Between-group comparisons were also computed for the area under the curve, an analytical approach for calculating overall cortisol secretion throughout the day.

RESULTS

Significant differences in the cortisol awakening response (CAR) were observed between children with hearing loss and children with normal hearing; however, no differences were observed between the two groups subsequent to the cortisol awakening response (60-min postawakening, 10:00 A.M., 2:00 P.M., and 8:00 P.M.). Compared with children with normal hearing, children with hearing loss displayed elevated cortisol levels at awakening and a reduced growth in cortisol secretion from awakening to 30-min postawakening. No significant differences in overall cortisol secretion throughout the day were found between groups (area under the curve). Finally, cortisol levels increased with increasing age for children with hearing loss but not for children with normal hearing.

CONCLUSIONS

Results of this preliminary study indicate a possible dysregulation in HPA axis activity in children with hearing loss characterized by elevated salivary cortisol levels at awakening and a diminished increase in cortisol from awakening to 30-min postawakening. The pattern of elevated cortisol levels at awakening is consistent with some studies on adults with burnout, a condition characterized by fatigue, loss of energy, and poor coping skills. These findings support the idea that children with hearing loss may experience increased vigilance and need to mobilize energy promptly in preparation for the new day.