Lisa Thorn

The awakening cortisol response: methodological issues and significance

The awakening cortisol response (ACR) is a discrete and distinctive part of the cortisol circadian cycle. In healthy adults salivary free cortisol concentrations increase by between 50 and 160% in the first 30 min immediately post-awakening (approximate average increase of 9 nmol/l, range 4–15 nmol/l, estimated to be equivalent to about three secretory episodes). However there are no agreed norms for the absolute concentrations of free cortisol in saliva either immediately post-awakening (range of 4.7–18.5 nmol/l) or 30 min post-awakening (range of 8.6–21.9 nmol/l). This review explores reasons for these discrepancies in normative data including confounding factors such as gender, age, awakening time, light and participant adherence. Although the physiological role of the ACR has not been clearly defined evidence is discussed that suggests it is under a distinct regulatory influence, different from the rest of the diurnal cortisol secretory cycle. Despite the difficulties associated with its measurement a range of studies have demonstrated an association between the ACR and psychosocial variables, stress and health. However it remains unclear whether positive affect and good health are consistently associated with larger or smaller awakening responses. It is early days in the search for the role and significance of the ACR. Its putative role in the regulation of physiological function across the day (e.g. the immune system) and its sensitivity to psychosocial variables make it a prime candidate as an intermediary linking mind and health.

The effect of dawn simulation on the cortisol response to awakening in healthy participants

Bright light exposure after awakening has been shown to elevate cortisol levels in healthy participants. The present study examined the effect of dawn simulation (a treatment for seasonal affective disorder) on the cortisol response to awakening and mood. Twelve healthy participants were supplied with a dawn simulator (The Natural Alarm Clock, Outside In, Cambridge Ltd), a bedside light that increases in intensity prior to awakening to approximately 250 lux over 30 mins when an audible alarm sounds. A counterbalanced study was performed on 4 consecutive normal weekdays, two of which were control days (no dawn simulation) and two experimental (dawn simulation). Saliva samples were taken immediately on awakening then at 15, 30 and 45 minutes post awakening on all 4 study-days. Total cortisol production during the first 45 mins after awakening was found to be significantly higher in the experimental condition than in the control condition. Participants also reported greater arousal in the experimental condition and there was a trend for an association between increased arousal and increased cortisol secretory activity under dawn simulation. This study provides supportive evidence for the role of light and the suprachiasmatic nucleus in the awakening cortisol response.

Diurnal patterns of salivary cortisol across the adolescent period in healthy females

When examining the diurnal profile of the hormone cortisol in children and adolescents developmental issues are particularly relevant. Previous findings regarding relationships between cortisol secretory activity and reproductive (pubertal) maturation lack clarity and may reflect methodological inconsistencies between studies. This study examined the diurnal cortisol profile across female adolescence, with a particular focus on an obvious and unique marker of development: menarche. In a cross-sectional design, 61 healthy female adolescents aged 9-18 years (mean age 13.89 years, S.D.+/-2.72) collected eight saliva samples per day on two consecutive weekdays. Samples were collected at awakening, 15, 30 and 45min and 3, 6, 9 and 12h post-awakening in order to capture both the cortisol awakening response (CAR) and the subsequent period of decline. Demographic information was recorded and participants also completed the Spielberger State-Trait Anxiety Inventory. Patterns of cortisol secretion exhibited good intra-individual stability across the two sampling days. Participants evidenced a robust diurnal pattern, with cortisol levels peaking approximately 30-45min post-awakening (the CAR) and steadily declining concentrations over the remainder of the day. Differences according to developmental status (in terms of whether or not participants had experienced first menses: menarche) were observed in the time of peak secretion of the CAR, and these distinct patterns could not be accounted for by group differences in demographic, situational or psychological characteristics measured in this study. This effect for the CAR was associated with the onset of menarche alone, unlike cortisol levels over the remainder of the day. For those who had undergone menarche, were older and of greater BMI, cortisol levels remained higher over the day. There was a significant difference in cortisol concentrations at 6h post-awakening between pre- and post-menarche groups. Again, these differences in daytime cortisol secretory activity could not be attributed to situational or psychological factors. Establishing patterns of cortisol secretion in healthy female adolescents provides an important baseline from which to investigate hypothalamic-pituitary-adrenal (HPA) physiology, measured via salivary cortisol, in adolescent populations with known or suspected psychopathology.

Delays of 5–15 min between awakening and the start of saliva sampling matter in assessment of the cortisol awakening response

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 15 min 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 45 min 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 4 min). Estimates of CAR magnitude were significantly greater on non-adherent days (delay of 5-15 min) compared to adherent days (delay<5 min). 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 5 min for 30 min post-awakening. Cortisol did not significantly increase until 10 min 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 10 min 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.

The cortisol awakening response, seasonality, stress and arousal: A study of trait and state influences

The aim of this study was to investigate the relationship between the cortisol awakening response (CAR) and two key state variables (morning stress and arousal) and the trait-like variable of seasonality as recent evidence suggests that the CAR is subject to both state and trait influences. The CAR was examined across two consecutive winter days in 50 healthy participants. Participants collected saliva samples in the domestic setting immediately on awakening, then at 15, 30 and 45min post-awakening on the two study days. Concomitant trait and state measures were examined, notably seasonal changeability in mood as a trait, and self-reported stress and arousal as state measures. Although there was correlational stability for measures of the CAR across days, there was a significant difference in the magnitude of the increase in cortisol levels following awakening between the two study days, being greater on the first sampling day. This reduction in the magnitude of cortisol increase was significantly associated with an observed reduction across the 2 days in self-reported arousal assessed at 45min following awakening. Participants reported greater arousal (more alert, active, energetic and stimulated, less drowsy, tired and sluggish) on the first study day than the second. Average CAR across days was associated with seasonality score, greater propensity for seasonal changes in mood being associated with smaller average CAR. High seasonality scorers were also more likely as a group to show a strong association between daily changes in state arousal and CAR. This study supports the view that the CAR is, in part, susceptible to short-term changes in state variables, notably perceived arousal, while observing a novel link between CAR and the trait variable of perceived seasonality. Finally a tentative finding suggests the importance of examining for possible interaction between trait and state effects, evidenced by a significantly greater association between state arousal changes and cortisol response changes in those with high (trait) seasonality.

Anxious attachment style and salivary cortisol dysregulation in healthy female children and adolescents

BACKGROUND Attachment style has been linked with basal cortisol secretion in healthy adult women. We investigated whether dysregulation in basal cortisol secretion may be evident in younger healthy females. METHODS Sixty healthy females aged 9-18 years (mean 14.16, SD ± 2.63 years) participated in the Attachment Style Interview (ASI). Eight saliva samples, synchronised to awakening, were collected per day on two consecutive weekdays to examine the cortisol awakening response (CAR) and the subsequent diurnal decline. RESULTS Participants exhibiting an anxious attachment style had higher cortisol levels on awakening, in contrast to those who were securely attached. The anxious insecure group also showed an attenuated CAR compared to all other participants. Attachment style groups did not differ in cortisol secretion over the remainder of the day. CONCLUSIONS These findings indicate that the same pattern of cortisol dysregulation associated with disorder in adulthood manifests as a function of anxious (but not avoidant) insecure attachment style in females during healthy childhood and adolescence.

State variation in the cortisol awakening response

Abstract The cortisol awakening response (CAR) is a much studied but poorly understood aspect of the circadian pattern of cortisol secretion. A Scopus search of “cortisol” and “awakening” reveals 666 publications in this area since 1997 when it was first identified by Pruessner and colleagues as a “reliable biomarker of adrenocortical activity”. The primary focus of the majority of these studies is centered on its utility as a biomarker associated with a range of psychosocial, physical and mental health variables. Such studies typically examine differences in the CAR (studied on 1 or 2 days) between healthy participants and other comparator groups of interest. Fewer studies (25 in our estimation) have examined correlates of day-to-day variation in the CAR in healthy participants, informing its role and regulation within the healthy circadian pattern of cortisol secretion. This is the first review to examine these studies which, although limited in number, offer a relatively coherent emerging story about state factors that influence the CAR and the impact of the CAR on daily functioning. Greater understanding of these issues helps illuminate the utility of the CAR as a promising biomarker in psychophysiological and epidemiological research. The review also highlights areas that require greater clarification and points to potentially fruitful areas of further research.

Seasonal differences in the diurnal pattern of cortisol secretion in healthy participants and those with self-assessed seasonal affective disorder

This study compared the daily pattern of free salivary cortisol secretion in winter and in summer between two groups; participants with self-assessed seasonal affective disorder (SAD) and age- and sex-matched healthy controls. Fifty-two participants completed the study with an equal number in each group. The diurnal pattern of cortisol secretion was assessed across two consecutive weekdays in summer, and two in winter, with conditions being counterbalanced. On each study day participants collected multiple saliva samples in the domestic setting to capture the cortisol awakening response (CAR) and declining levels across the day. In addition, perceived stress, anxiety, depression, state stress and state arousal were assessed using validated questionnaires. There was no evidence for any seasonal changes in psychological data or cortisol pattern for the healthy control population. In summer, self-assessed SAD and control participants had similar psychological and cortisol profiles. In winter however, SAD participants reported greater depression, stress and anxiety, and lower levels of arousal. Furthermore, the CAR was significantly attenuated in SAD participants during winter months. There was no difference in cortisol levels during the rest of the day between controls and SAD participants in winter. In line with the above findings and previous research, there was an inverse relationship between the increase in cortisol following awakening and a measure of seasonality in winter. Furthermore in winter, a general dysphoria construct correlated inversely with the CAR, indicating that participants reporting greater depression, stress and anxiety and lower arousal, exhibited lower CARs. In conclusion, during the shortened photoperiod in winter, the cortisol response to awakening is attenuated in participants with self-assessed SAD in comparison to controls. These findings contribute to the understanding of the physiology of SAD.

Diurnal patterns of salivary cortisol and DHEA in adolescent anorexia nervosa

Although there is well-documented evidence for hyperactivity of hypothalamic–pituitary–adrenal (HPA) axis function in anorexia nervosa (AN), there has been little research into secretory patterns of salivary cortisol and dehydroepiandrosterone (DHEA) in this condition. The cortisol awakening response (CAR), a prominent and discrete feature of the cortisol cycle, has not been extensively explored in adolescent AN. Saliva samples were collected at awakening, 30 min and 12 h post-awakening on two consecutive weekdays from eight female adolescents with clinically diagnosed AN and 41 healthy control (HC) age-matched females. Adolescent AN patients had greater salivary cortisol and DHEA concentrations than HC girls at all points. Increased hormone secretion was unrelated to body mass index. However, despite hypersecretion of both hormones, the circadian pattern including the CAR paralleled that of the HC group. Findings from this preliminary study confirm dysregulation of HPA axis function in adolescent AN as evidenced by hypersecretion of both cortisol and DHEA, which share the common secretagogue adrenocorticotropic hormone. However, the parallel diurnal profiles for AN and HC participants, including the CAR, may indicate hypersecretion per se rather than differential regulation of the diurnal pattern of these two adrenal steroids in AN.

Differences between diurnal patterns of salivary cortisol and dehydroepiandrosterone in healthy female adolescents.

The adrenal hormones cortisol and dehydroepiandrosterone (DHEA) share a common secretagogue: adrenocorticotropic hormone; however, secretion of these hormones can be dissociated suggesting subtle individual regulation at the level of the adrenal gland. We examined differences in the diurnal patterns of cortisol and DHEA secretion in healthy adolescent girls, with the aim of informing the possibility of exploiting these differences to aid interpretation of data from clinical populations in which these patterns can become dysregulated. Fifty-six healthy females aged 10–18 years provided saliva samples at 0 and 30 min (morning samples) and 12 h post-awakening on 2 consecutive weekdays. For morning salivary cortisol in relation to morning DHEA concentrations, correlational analysis revealed only a trend (p = 0.054). Similarly, the association between evening cortisol and DHEA was characterised as a trend (p = 0.084). Mean morning DHEA concentrations showed more day-to-day consistency than equivalent cortisol samples (r = 0.829 for DHEA and 0.468 for cortisol; z = 3.487, p < 0.0005). Unlike the cortisol pattern, characterised by a marked awakening response (cortisol awakening response, CAR), a significant rise in DHEA concentration post-awakening was not evident. Finally, there was a strong association between morning and evening concentrations of DHEA, not found for cortisol. The study shows differences in cortisol and DHEA secretion in the post-awakening period and informs work that seeks to examine correlates of dysregulated hypothalamic–pituitary–adrenal axis function. Parallel examination of both hormones enables enhanced interpretation of aberrant patterns of the CAR, i.e. an exploration of whether dysregulation affects both hormones (reflecting overall steroidogenic capacity) or cortisol alone (CAR-specific mechanisms).