Linking psychosocial measures to the cortisol awakening response (CAR) demands accurate saliva sampling times. Monitoring adherence to the saliva sampling protocol requires electronic monitoring of ...both awakening and sampling times since self-reported times are inaccurate. Delays greater than 15min between awakening and commencement of saliva sampling reduce CAR magnitude. Less delay has been judged tolerable but remains unexplored for different magnitude measures, and for timing of the CAR peak.
Study 1: Fifty healthy females (21±4 years) were instructed to collect saliva on four days at 0, 15, 30 and 45min post-awakening (samples 1–4). Both self-reported awakening and sampling times were electronically monitored using actigraphy and track caps. Self-reported awakening was later than actigraph estimated awakening (median difference of 4min). Estimates of CAR magnitude were significantly greater on non-adherent days (delay of 5–15min) compared to adherent days (delay<5min). On non-adherent compared to adherent days cortisol on average peaked earlier, at sample 3 rather than at sample 4.
Study 2: Accurately timed cortisol values were obtained in an intensive investigation of 10 participants who collected saliva on 2 days every 5min for 30min post-awakening. Cortisol did not significantly increase until 10min post-awakening, suggesting a time lag may be typical between awakening and observation of a cortisol increase.
We conclude that moderate delays between awakening and collection of saliva samples previously considered tolerable result in erroneous estimation of CAR magnitude and timing of the peak. These results are attributed to an approximate 10min time lag between awakening and the start of the cortisol rise. The absence of this latent period in calculations leads to overestimation of the CAR magnitude on moderately non-adherent sampling days. These findings, if more universally generalizable, will further theoretical understanding of the physiology of the CAR, but are methodologically challenging for researchers since self-reported awakening times are not accurate enough to override the concerns raised. However accurate electronic measurement of adherence to protocol would enable sampling delays to be taken into account in computing CAR estimates.
Highlights • All cortisol data objectively verified for awakening and saliva sampling times. • Cortisol growth curve plot against real-time not affected by protocol deviance. • In healthy young ...adults the mean CAR was a 100% increase from awakening cortisol. • Curvilinear delay effect on CAR size if protocol times wrongly assumed accurate. • Electronic-monitoring vital for CAR measurement and meaningful interpretation.
Secretory immunoglobulin A (sIgA) in saliva and
cardiovascular reactions to mental arithmetic and cold
pressor tasks were recorded in 16 healthy young men on
two sessions, 4 weeks apart. Both tasks ...elicited significant
increases in sIgA secretion rate, reflecting increases
in both salivary volume and sIgA concentration. Whereas
mental arithmetic elicited a mixed pattern of alpha- and
beta-adrenergic cardiovascular reactions, the pattern of
reactions to cold pressor was predominantly alpha-adrenergic.
Task levels of sIgA secretion rate, sIgA concentration,
and saliva volume showed moderate to high test–retest
reliability (r = .52–.83), although
test-retest correlations were less impressive for change
scores (r = −.19–.53).
The pattern of correlations between change in sIgA secretion
rate and cardiovascular reactivity variables was inconsistent.
Background: Evidence linking fitness and decreased psychosocial stress comes from studies of athletes and typically relies upon self-report measures. Furthermore, there is little evidence regarding ...the impact of physical activity (PA) prior to a stressor. The aims of this study were to determine whether fitness and prior PA influence cortisol concentrations during psychosocial stress.
Methods: Seventy-five non-athletic participants took part in a submaximal walk prior to the Trier Social Stress Test for Groups (TSST-G). During the walk, fitness was assessed using heart rate (HR). A further 89 participants took part in the TSST-G without the walk. Stress responsiveness was assessed using salivary cortisol collected at 10-min intervals on seven occasions.
Results: Hierarchical multiple regression revealed that average walking HR accounted for 9% of the variance in cortisol secretion (P = .016), where a higher HR was associated with higher cortisol secretion. Between-subjects ANCOVA revealed that the walking group had a significantly lower cortisol secretion than the non-walking group (P = .009).
Conclusions: These findings indicate that fitter individuals have reduced cortisol secretion during psychosocial stress. They also indicate that prior PA can reduce cortisol concentrations during psychosocial stress and are suggestive of a role of PA in reducing the impact of stress on health.
Highlights • The cortisol awakening response (CAR) was measured at 5 min intervals for 60 min in healthy participants. • Electronic monitoring of awakening and sampling times enabled careful checking ...of adherence to the required protocol. • Data with delay >5 min between awakening and collection of the first sample were excluded from the analysis. • In the 0–15 min CAR period a quadratic effect was observed: no difference between the 0 and 5–10 min samples. • This latent period can account for overestimation of the CAR when analyzing data from moderately non-adherent days.
The cortisol awakening response (CAR) is a crucial point of reference within the healthy cortisol circadian rhythm, with cortisol secretion typically peaking between 30 and 45 min post awakening. ...This chapter reviews the history of investigation into the CAR and highlights evidence that its regulation is relatively distinct from cortisol secretion across the rest of the day. It is initiated by awakening, under the influence of the hypothalamic suprachiasmatic nucleus, and "fine tuned" by a direct neural input to the adrenal cortex by the sympathetic nervous system. This chapter also examples the CAR in relation to other awakening-induced processes, such as restoration of consciousness, attainment of full alertness, changes in other hormones, changes in the balance of the immune system, and mobilization of the motor system, and speculates that there is a role for the CAR in these processes.
The cortisol awakening response (CAR) is associated with various aspects of cognition, including executive function, in older adult and clinical samples. However, the association between these ...variables in the healthy functioning population is not well understood due to the limited number of appropriately controlled studies. This study explored the association between the CAR and a set shifting index of executive function in 55 (44 females) healthy participants aged 20.2 ± 3.0 years. Notoriously, assessment of the CAR from self-collected saliva samples within the domestic setting is subject to sample timing error, so electronic monitoring of both awakening and sampling times were employed. Participants attended the laboratory in the afternoon of CAR assessment for testing on the Attention Switching Task of the CANTAB neuropsychological testing battery. A positive association was found between CAR magnitude and attention-switching performance in the afternoon of the same day. This was independent of known relevant CAR covariates, but only evident in CAR data collected without delay exceeding 8 min post-awakening. These findings offer insight into a potential role for the CAR in modulating cognitive functions associated with the pre-frontal cortex.
•Explored the CAR and same day attention switching in 55 healthy young adults.•Positive association between CAR and attention switching performance.•Associations only evident where CAR sampling was accurate to within 8 min.•Results indicate a role for the CAR in healthy pre-frontal cortex function.
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