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Young Children's Full-Day Patterns of Cortisol Production on Child Care Days

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To examine toddlers' full-day patterns of cortisol production on child care days and non-child care days, with a particular focus on whether the mid-afternoon elevations at child care persist into the evening or decrease to typical levels observed on non-child care days. A prospective observational study. Four child care centers in a suburban, mid-Atlantic area. Forty-two children aged 16 to 24 months attending full-day child care. MAIN EXPOSure: Full-day child care. Salivary cortisol samples obtained at wake-up, mid-morning, mid-afternoon, and bedtime for children on 2 child care days and 2 non-child care days. Children showed different patterns of cortisol production on child care days compared with non-child care days (chi(2)(4) = 18.21, P = .001). Child care days were characterized by an afternoon increase in cortisol levels (unlike non-child care days) and decreases to bedtime values that were comparable with levels on non-child care days. Results suggest that the effects of child care on children's cortisol production are time limited across the day.
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ARTICLE
Young Children’s Full-Day Patterns of Cortisol
Production on Child Care Days
Melissa Manni Sumner, PhD; Kristin Bernard, MA; Mary Dozier, PhD
Objective:To examine toddlers’ full-day patterns of cor-
tisol production on child care days and non–child care days,
with a particular focus on whether the mid-afternoon el-
evations at child care persist into the evening or decrease
to typical levels observed on non–child care days.
Design:A prospective observational study.
Setting:Four child care centers in a suburban, mid-
Atlantic area.
Participants:Forty-two children aged 16 to 24 months
attending full-day child care.
Main Exposure:Full-day child care.
Outcome Measure:Salivary cortisol samples obtained
at wake-up, mid-morning, mid-afternoon, and bedtime for
children on 2 child care days and 2 non–child care days.
Results:Children showed different patterns of cortisol pro-
duction on child care days compared with non–child care
days (2
4=18.21, P=.001). Child care days were character-
ized by an afternoon increase in cortisol levels (unlike non–
child care days) and decreases to bedtime values that were
comparable with levels on non–child care days.
Conclusion:Results suggest that the effects of child care
on children’s cortisol production are time limited across
the day.
Arch Pediatr Adolesc Med. 2010;164(6):567-571
FROM ABOUT 6WEEKS OF AGE,
infants begin to show a di-
urnal pattern of cortisol pro-
duction with an early morn-
ing peak and an evening
nadir.1This pattern becomes increas-
ingly stable across the first year of life,2but
remains “immature” through the pre-
school years.3(p126) The adultlike pattern in
which a decrease is seen from mid-
morning to mid-afternoon does not emerge
until children are 5 to 6 years of age3;
rather, infants, toddlers, and preschool-
ers show relatively flat mid-morning to
mid-afternoon slopes in cortisol when they
are at home.3,4 It is during this time of rela-
tive immaturity that the system appears
particularly susceptible to environmen-
tal influences on daytime cortisol produc-
tion patterns.5-7
On child care days, many children show
an increase in cortisol from mid-
morning to mid-afternoon,3,4 rather than
the decrease that characterizes the ma-
ture pattern of cortisol production.8This
morning to afternoon increase is a robust
finding that has emerged across day care
centers varying in quality,9child sex,3,9 and
various napping conditions.3However, it
has not been clear whether cortisol val-
ues decrease during the evening to the bed-
time nadir that is typical on days when
children do not go to child care or whether
values continue to be elevated at night.
This is an important step in clarifying the
persistence and meaning of child care ef-
fects on neuroendocrine functioning, es-
pecially given that chronic activation of the
hypothalamic-pituitary-adrenal system has
been associated with risk of cognitive im-
pairments and compromised immune
function.7
Gunnar and colleagues3,7,9 have stud-
ied the effects of child care on children’s
production of cortisol extensively. The
most robust finding is that cortisol in-
creases are seen from mid-morning to mid-
afternoon when children are in the child
care environment.3,9 Although a number
of variables have been identified as poten-
tially important in mediating or moderat-
ing the effects of child care on cortisol lev-
els, the picture is complex.
Quality of day care has been associ-
ated with the rise in cortisol, with higher-
quality day care associated with smaller in-
creases in cortisol.10 Even in good to
excellent child care, however, increases in
cortisol have usually been seen.9A shy or
inhibited temperament has been associ-
Author Affiliations:
Department of Psychology,
University of Delaware,
Newark.
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ated with elevated afternoon cortisol production in child
care,4but peer rejection, which represents the opposite
behavioral tendencies as shyness, has also been associ-
ated with elevated afternoon levels of cortisol during the
preschool day.11 Watamura et al3ruled out the possibil-
ity that napping patterns were responsible for the ef-
fects seen. Gunnar et al11 emphasized that the effects are
complex. Nonetheless, across a range of conditions, young
children often show a reversed pattern of cortisol pro-
duction during child care days compared with cortisol
production on non–child care days.
The primary aim of the present study was to examine
daily cortisol production patterns among toddlers at-
tending full-day center-based care and to compare pat-
terns on child care vs non–child care days. Toddlers were
expected to show different daytime patterns on child care
days vs non–child care days. Differences were expected
in mid-afternoon values, with higher afternoon values at
child care compared with afternoon values on non–
child care days, replicating prior findings.9Of particular
interest was whether the mid-afternoon elevations at child
care persisted into the evening or whether levels de-
creased, reaching a nadir as on non–child care days.
METHODS
PARTICIPANTS
Forty-four toddlers (aged 16-24 months) were recruited into
the study. Children attended full-day center-based child care.
Cortisol data were collected for 42 of the 44 children (1 child
refused sampling and 1 child left the child care center before
sampling was complete). Analyses were conducted in the 42
children who completed salivary cortisol sampling. Of this group,
27 were boys and 15 were girls. Twenty-four were European
American, 10 were biracial, 7 were African American, and 1
was Asian American. Annual family income ranged widely, with
some families receiving purchase-of-care subsidies and some
earning up to $200 000 (range, $4056-$200 000; median,
$85 000). Mean age at sampling was 21 months (SD, 2.48
months). All children had been enrolled a minimum of 2 months
in their respective classrooms before measures were collected.
CHILD CARE SETTINGS
Children were recruited from 4 child care centers in a subur-
ban, mid-Atlantic area. Centers were accredited by the Na-
tional Association for the Education of Young Children
(NAEYC). The NAEYC Academy for Early Childhood Pro-
gram Accreditation administers a voluntary accreditation sys-
tem to help raise the quality of US child care centers. All cen-
ters were chosen from a NAEYC list to ensure a minimum
standard of care. Included among these was a university child
care center that enrolled children of faculty, staff, and com-
munity members, offering subsidized care as needed. Most chil-
dren (73%) were recruited from 6 classrooms at the university
child care center. The remaining children were sampled from
1 toddler classroom in each of the other 3 child care facilities.
At all centers, classrooms were self-enclosed, separated by age
group (infant, toddler, and preschool), and had staff to child
ratios between 1:3 and 1:6. The quality of the child care envi-
ronment was rated by observers using a standardized instru-
ment, which we will describe more fully.
PROCEDURE
Saliva samples were collected from children on 2 days when
children were not in child care and on 2 days when children
were in child care. Trained research assistants instructed par-
ents in how to collect children’s home samples of saliva. Par-
ents were instructed to collect samples on non–child care days
at wake-up, mid-morning (around 10 AM), mid-afternoon
(around 3 PM), and bedtime for 2 days. Wake-up samples were
collected between 6:30 AM and 9:37 AM (mean, 7:50 AM). Mid-
morning samples were collected between 8:45 AM and 12:30
PM (mean, 10:53 AM). Mid-afternoon samples were collected
between 1:30 PM and 7:00 PM (mean, 3:44 PM). Bedtime samples
were collected between 7:10 PM and 11:13 PM (mean, 8:41 PM).
Parents were also asked to collect salivary samples at wake-up
and bedtime for 2 days that the child attended child care.
Wake-up samples on these days were collected between 6:00
AM and 8:50 AM (mean, 7:11 AM). Bedtime samples were col-
lected between 7:08 PM and 10:03 PM (mean, 8:32 PM). Trained
research assistants collected mid-morning and mid-afternoon
saliva samples from the children on child care days. Mid-
morning samples at child care were collected between 8:35 AM
and 11:30 AM (mean, 10:03 AM). Mid-afternoon samples at child
care were collected between 2:30 PM and 4:30 PM (mean, 3:27
PM). Owing to the variability of collection times within each
sampling occasion, an alternative time structure (explained be-
low) was used to more accurately represent sampling times and
intervals.
Compliance caps (MEM Tracking Caps, Aardex, Corpora-
tion) were used to track the time of cortisol sampling when chil-
dren were not at child care. These caps were placed on the vi-
als that contained the dental cotton rolls used for saliva sampling.
When the cap was opened, a microchip recorded the time, pro-
viding verification of sampling time. The use of such caps has
been shown to enhance sampling compliance.12
Saliva samples were collected by placing one end of a den-
tal cotton roll in a child’s mouth to wet it. The cotton was then
dipped in a cup containing 0.8 g of flavored beverage crystals
(cherry-flavored drink mix) and placed back in the child’s mouth.
The drink crystals were used to stimulate salivation. Use of the
flavored crystals has been found to affect cortisol levels only
minimally when the enzyme immunoassay is used.13,14 After one
end of the cotton roll was soaked with saliva, the roll was placed
in a prelabeled vial and stored in the freezer until the samples
were returned to the laboratory.
MEASURES
Cortisol
The saliva samples were stored in a freezer at the laboratory at
−20°C until they were assayed. Samples were assayed using an
enzyme immunoassay (Salimetrics, LLC). On the day of assay-
ing, samples were thawed and centrifuged at 3000 rpm for 10
minutes and transferred into test wells with a pipette. The mini-
mum sample test volume was 10 µL. All samples from a child
were included in the same assay batch to minimize variability.
Standards were included in every assay to ensure that assaying
properties remained constant. A laboratory control was in-
cluded in each assay as well. The intraassay and interassay co-
efficients of variation were 3.5% and 5.1%, respectively.
Cortisol values 3 SDs above the mean for that time of day
were considered outliers and were not included in the analy-
ses. This is a commonly used procedure for dealing with cor-
tisol samples that may have been sampled without adherence
to sampling guidelines.15 Eleven outliers were removed from
the data set (representing less than 2% of the data). Averaged
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values for time and context were then computed to create an
average wake-up, mid-morning, mid-afternoon, and bedtime
value for both child care and non–child care days. As is typi-
cally the case with cortisol data, the distribution of the data for
the times measured was positively skewed. To normalize the
cortisol distributions, the convention of log10 transformation
was used.
Classroom Rating
Observations were conducted in each classroom to obtain a qual-
ity of care measure to be used as a control variable if indicated
in preliminary analyses. The assessment instrument used was
the Infant-Toddler Environmental Rating Scale–Revised
(ITERS-R).16 The ITERS-R is a standardized rating scale of child
care environments, consisting of 39 items organized into 7 sub-
scales (space and furnishings, personal care routines, listen-
ing and talking, activities, interaction, program structure, and
parents and staff) and a total score rated on a 7-point scale.
The overall scale has a high level of internal consistency, with
a Cronbach of 0.93.15
For this study, 1 observer, blind to other data, rated the class-
rooms. The observer obtained reliability with an expert ob-
server, reaching 91% agreement on items over the course of 3
classroom observations (mean weighted =0.88). Total scores
for the 9 classrooms rated in the present study ranged from 4.74
to 6.40 (good to excellent quality range; mean, 6.22 [SD, 0.29]).
Sleep, Health, and Eating Diary
Parents maintained a diary of child sleep patterns, food in-
take, as well as general health on days that the samples were
collected. Diaries were monitored to ensure sampling guide-
lines were followed. If children were sick at the time that par-
ents were asked to sample, the sampling was delayed until the
child was well again.
STATISTICAL ANALYSIS
To address the central study question regarding patterning of
cortisol production on child care vs non–child care days, data
were analyzed using hierarchical linear modeling.17 Hierarchi-
cal linear modeling accounts for the nonindependence of mul-
tiple observations nested within an individual, simulta-
neously estimating within- and between-subject variation. The
nested structure permits variability in the number and spac-
ing of data points, allowing for inclusion of participants who
are missing 1 or more points of data. In the current study, the
repeated measurements of cortisol levels on child care and non–
child care days were the level 1 data. The level 2 data unit was
the child.
Given the between-subject variability in sampling times, it
was important to create a time variable that most accurately
captured the timing of and spacing between samples. Relying
on mean times of assessment for each targeted occasion (wake-
up, mid-morning, afternoon, and bedtime) across individuals
may have resulted in a less accurate representation of diurnal
changes. Thus, an alternative time structure was used for the
current study, assigning individuals’ cortisol measurements to
specified time-class intervals. This approach was based on that
used by King et al18 to characterize time in longitudinal trauma
research. Two time-class intervals were specified for each tar-
geted occasion (wake-up, mid-morning, afternoon, and bed-
time) based on the range of sampling times. This restructur-
ing resulted in a total of 8 time-class intervals. The average time
was calculated for samples falling within each specific time-
class interval. The final time variable represented hours from
the initial sampling interval for each sample. Using a consis-
tent time structure across individuals allowed for recentering
at meaningful points to compare cortisol values at particular
times of the day.
The data were analyzed using a multivariate statistical model.
Log-transformed cortisol values measured across each of the 8
times on child care and non–child care days were stacked to
create the dependent variable. First, the full-day pattern of cor-
tisol production was compared for child care and non–child
care days. Second, planned comparisons were tested to fur-
ther examine the nature of differences between child care and
non–child care days. Specifically, hypotheses were tested re-
garding differences in the slopes of cortisol change between con-
texts, as well as differences in cortisol levels at each of the 8
times. Of particular interest was whether children’s levels of
cortisol at bedtime were significantly different between con-
texts. The following level 1 within-individual model was used
log cortti =(home)it [h0i⫹␲h1i(time) ⫹␲h2i(time Q)⫹␲h3i
(time C)]
(CCARE)it[c0i⫹␲c1i(time) ⫹␲c2i(time Q)⫹␲c3i(time C)]eti,
where Log cortti is the log-transformed cortisol value for child
iat time t; (home)it is a dummy indicator that is 1 for data on
non–child care days and 0 for data on child care days; (CCARE)it
is a dummy indicator that is 1 for data on child care days and
0 for data on non–child care days; time, time Q, and time C
represent the linear, quadratic, and cubic time variables (in
hours), respectively; h1iand c1iare the regression coeffi-
cients representing the slope of linear change in log cort at the
first time point for non–child care (ie, home) and child care
days, respectively; h2iand c2iare the regression coefficients
representing the slope of quadratic change in log cort at the first
time point for non–child care and child care days, respec-
tively; h3iand c3iare the regression coefficients representing
the slope of cubic change in log cort across time points for non–
child care and child care days, respectively; and eti is the within-
individual error in child i’s log cort. We examined an uncon-
ditional level 2 model with 0i,1i,2i, and 3irandom.
RESULTS
PRELIMINARY ANALYSES
Preliminary analyses were conducted to examine poten-
tial effects of demographic and quality of care variables
on cortisol production. Cortisol patterning has been
shown to vary by age during early childhood,3but no sig-
nificant associations between age and cortisol concen-
trations emerged for any of the time points in the pres-
ent study (P=.75). Furthermore, cortisol levels were not
significantly associated with child sex or ethnicity, fam-
ily income, or quality of child care (ie, total scores on
the ITERS-R).
FULL-DAY CORTISOL PATTERNS ON CHILD
CARE AND NON–CHILD CARE DAYS
To examine context-related differences in the full-day pat-
tern of cortisol production, we first tested whether the
overall trajectories of change differed between contexts.
Results of the full model are summarized in Table 1.
As predicted, the overall trajectories of change in corti-
sol on non–child care vs child care days were signifi-
cantly different (2
4=18.21, P=.001) (Figure).
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To examine the nature of the differences in cortisol
change between contexts, the slopes of the trajectories
were first compared. As predicted, there was a signifi-
cant difference in the cubic function between contexts
(2
1=10.75, P=.001). As can be seen in the Figure, child
care days were characterized by a morning decrease, then
an afternoon rise, followed by a bedtime drop in cortisol
levels, whereas non–child care days showed a morning
decrease, then a flattening across the afternoon, fol-
lowed by a similar decline at bedtime. Thus, the differ-
ences appear to be specific to the afternoon times.
Finally, comparisons between child care vs non–child
care coefficients were tested for each of the 8 time points
(Table 2). As predicted, there were significant differ-
ences in the afternoon, such that cortisol levels were higher
on child care days than on non–child care days. This effect
held for samples collected both earlier (2
1=7.94, P=.005)
and later (2
1=10.38, P=.002) in the afternoon. As ex-
pected, there were no significant differences between con-
texts for samples collected at wake-up and mid-morning
(P.05). Of particular interest was whether cortisol lev-
els remained higher on child care days than non–child care
days or returned to typical levels by bedtime. As can be seen
in Table 2, there were no significant differences in cortisol
levels at bedtime samples collected earlier in the evening
(2
1=0.09, P=.77). However, there were significant differ-
ences between contexts for samples collected later in the
evening (2
1= 5.76, P=.02), such that cortisol levels on child
care days were lower than cortisol levels on non–child care
days. As the restructuring of the time intervals resulted in
a lower number of samples per time point, this particular
finding should be interpreted with caution.
COMMENT
Consistent with previous studies of cortisol patterns on non–
child care days,17 toddlers showed highest levels at wake-up
and lowest levels at bedtime. On days when children at-
tended child care, however, they showed increases in cor-
tisol production from mid-morning to mid-afternoon and
decreases from afternoon to bedtime. Most importantly, chil-
dren’s cortisol values at bedtime were as low on child care
days as they were on non–child care days despite the af-
ternoon rises. Although afternoon elevations have been well
documented among preschool samples,10,16,19 this study pro-
vides the first data, to our knowledge, regarding post–
child care cortisol levels on days that children attend full-
day day care. These findings suggest that bedtime cortisol
levels are at least as low on child care days as on non–child
care days.
Comparison of samples obtained in the later evening
hours suggested that children’s cortisol levels may actu-
ally be lower on child care days than non–child care days
just before sleep. Given that this difference was only sig-
nificant for bedtime samples collected later in the evening,
it may be an effect of separating the bedtime samples into
2 time intervals, resulting in fewer data per time point. On
the other hand, children’s systems may be downregulat-
ing cortisol production in the evening to compensate for
elevated afternoon levels. Replication of this finding would
be important before further speculation regarding a pos-
sible homeostatic mechanism.
Although elevations of cortisol on child care days do not
appear to be associated with higher bedtime values of cor-
Table 1. Multilevel Modeling Coefficients of Change
in Salivary Cortisol Across Child Care
and Non–Child Care Daysa
Effect
Change in Salivary
Cortisol
P
ValueCoefficient (SE) t41
Home intercept, h00 −0.472 (0.071) −6.69 .001
Child care intercept, c00 −0.483 (0.058) −8.27 .001
Home linear slope, h10 −0.166 (0.039) −4.24 .001
Child care linear slope, c10 −0.250 (0.037) −6.81 .001
Home quadratic slope, h20 0.023 (0.007) 3.32 .002
Child care quadratic slope, c20 −0.048 (0.006) 7.41 .001
Home cubic slope, h30 −0.001 (0.000) −3.34 .001
Child care cubic slope, c30 −0.003 (0.000) −8.25 .001
Abbreviation: SE, standard error.
aOverall home vs child care trajectories differed significantly (2
4=18.21,
P=.001).
0.2
1.2
1.0
0.8
0.6
0.4
1.4
1.6
1.8
6 AM 9 AM 12 PM 3 PM 6 PM 9 PM
Time
Log-Transformed Cortisol Value, µg/dL
Home
Child care
Figure. Cortisol level patterns on child care days vs non–child care days for
the full sample. Error bars represent standard error.
Table 2. Between-Context Comparisons of Fixed Effects
Across Time Points
Sample
Mean Time
of Cortisol
Measurement
Coefficient
2
Home Child Care
Wake-up
Early 7:09 AM −0.47 −0.48 0.02
Late 8:26 AM −0.65 −0.73 1.62
Mid-morning
Early 10:16 AM −0.80 −0.87 1.12
Late 11:40 AM −0.85 −0.86 0.02
Afternoon
Early 2:50 PM −0.89 −0.72 7.94a
Late 3:52 PM −0.90 −0.69 10.38a
Bedtime
Early 8:05 PM −1.14 −1.17 0.09
Late 9:14 PM −1.31 −1.56 5.76b
aP.01.
bP.05.
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tisol production, it is unclear whether these heightened lev-
els of cortisol production carry more lasting effects on chil-
dren’s development. In animal studies, chronic activation
of the hypothalamic-pituitary-adrenal axis has been linked
to deleterious effects on brain development, poorer im-
mune functioning, and compromised stress-response sys-
tems.20 Roisman and colleagues21 examined the effects of
early care experiences (ie, maternal insensitivity and time
in child care) on later hypothalamic-pituitary-adrenal axis
functioning. More time in child care before age 3 years was
associated with lower awakening levels of cortisol at age
15 years. More longitudinal studies of this nature are needed
to further examine whether the cortisol increases at child
care reflect normative, context-specific responses or con-
fer risk of problems later in life.
There are limitations to the conclusions that can be
drawn from the results of the present study. Although
afternoon elevations have been documented previ-
ously,4the assessment of full-day patterning among tod-
dlers should be replicated. Additionally, the age range
included here was narrow. As age effects related to mid-
afternoon cortisol production at child care have been
noted in other studies,15 investigation of full-day pat-
terning across early childhood (infancy, preschool, and
school age) is warranted. Furthermore, findings may not
be generalizable to different types of child care settings
(eg, home-based child care and relative care) or to child
care centers that are rated poor to adequate by standard
quality of care measures. The present study assessed cor-
tisol levels among children who attended center-based
care facilities of good quality as rated by the ITERS-R.
Previous research has indicated that young children
show mid-morning to mid-afternoon increases in corti-
sol on child care days, unlike the pattern they show on
non–child care days.3,9 The present study extended these
findings, demonstrating that young children’s cortisol level
at bedtime on child care days returns to levels at least as
low as on non–child care days. Thus, the effects of child
care on daytime patterning of cortisol production are not
seen in elevated evening levels, suggesting time-limited
elevations across the day. Nevertheless, it will be impor-
tant to examine whether there are long-term conse-
quences of the altered diurnal patterns, despite the ap-
parent return to low levels at bedtime.
Accepted for Publication: October 8, 2009.
Correspondence: Mary Dozier, PhD, Department of Psy-
chology, University of Delaware, 108 Wolf Hall, New-
ark, DE 19716 (mdozier@udel.edu).
Author Contributions: Study concept and design: Sum-
ner and Dozier. Acquisition of data: Sumner. Analysis and
interpretation of data: Bernard and Dozier. Drafting of the
manuscript: Sumner, Bernard, and Dozier. Critical revi-
sion of the manuscript for important intellectual content: Ber-
nard and Dozier. Statistical analysis: Bernard. Obtained
funding: Dozier. Study supervision: Dozier.
Financial Disclosure: None reported.
Funding/Support: This project was supported by grants
R01MH052135, R01MH074374, and R01MH084135 from
the National Institute of Mental Health. Dr Dozier par-
ticipated in a National Institute of Mental Health–
funded network (Megan Gunnar, PhD, principal inves-
tigator), which provided intellectual support for the ideas
developed. The content is solely the responsibility of the
authors and does not necessarily represent the official
views of the National Institute of Mental Health or the
National Institutes of Health.
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... As follows, cortisol in young children might sometimes increase (or remain elevated) following naps (see Gribbin et al., 2012;Tervahartiala et al., 2020;Tribble et al., 2015;Ward et al., 2008;Watamura et al., 2004). In contrast to the steady decline of cortisol release over a day in adults, this diurnal cortisol rhythm in young children is disrupted in form of a bump or a plateau as demonstrated by cortisol collections ranging from morning to evening Sumner et al., 2010). Interestingly, disruptions in declining diurnal cortisol foremost appeared if naptimes were ordered (Thorpe et al., 2018). ...
... Two metaanalyses have shown that the effect of childcare on cortisol was less prevalent during children's first compared to their second year of life (Geoffroy et al., 2006;Vermeer & van IJzendoorn, 2006). In fact, little stress research has been conducted in children aged between 12 and 36 months; and only very rarely is research on children's diurnal cortisol based on repeated measures spread out from morning over afternoon to evening and bedtime, comparing the cortisol measures at home and in childcare (c.f., Groeneveld et al., 2010;Sumner et al., 2010). ...
... Although these studies carefully compared cortisol levels from the same child in childcare and at home, findings are mixed (see Table 1 for an overview). Some of these studies reported increases in midmorning to midafternoon cortisol (when cortisol is expected to decline) in center-based care, but not at home (Drugli et al., 2018;Sumner et al., 2010). This confirms Vermeer and van IJzendoorn (2006)'s speculation that children in center-based care (particularly children under three) show elevated cortisol levels due to their stressful interactions in a group setting. ...
Article
Four saliva probes were collected per day from 104 children (10 to 35 months old) transitioning from home (T0) to childcare across a four-month period (until T3), resulting in over one thousand cortisol values. Latent Profile Analysis classified three profiles within a regular spectrum of children’s cortisol rhythms and described a fourth hypocortisol stress profile. Further Latent Transition Analysis revealed that profiles frequently changed across the transition but stabilized at T3. Most importantly, regular profiles across transition most likely occurred with high AQS scores of mother-child and care provider–child attachment. A machine learning procedure (XGBoost) featured predictors for stress profiles at T3 (when the child ought to be adjusted and stress profiles should be rare) referring to characteristics of the children (e.g., gender, number of siblings, peer contact before entry), the mothers (their worries), the care providers (their work experience, engagement, attachment) and the groups in the childcare centers (e.g., size, age differences, illness frequency). As a result, experience with siblings and peers before entry facilitated the transition. However, most conditions not linearly affecting children’s cortisol revealed even opposite effects when analyzed at different times. For example, smaller group size and large age-differences at T1 helped the child to stabilize a Regular profile, perhaps due to better control over the situation and greater support from the older children in the group. At T3, however, Regular profiles were associated with larger group size and smaller age-differences which might be helpful for establishing close peer relationships to buffer stress.
... A meta-analysis by Vermeer and van Ijzendoorn (2006) suggested that toddlers tend to show higher levels of cortisol in childcare when compared with them being at home, and they do so more than other age groups. This finding has been supported in further studies (Bernard et al. 2015;Drugli et al. 2018;Groeneveld et al. 2010;Ouellet-Morin et al. 2010;Sumner, Bernard, and Dozier 2010;Vermeer et al. 2010). Indeed, the transition to childcare might elicit especially high cortisol levels (Ahnert et al. 2004;Bernard et al. 2015). ...
... To the best of our knowledge, no one has yet examined evening home levels in toddlers during their transition to childcare. Sumner, Bernard, and Dozier (2010), as well as Groeneveld et al. (2010), registered a decrease of cortisol in the evening after childcare, but the participants of those studies were not in the process of transitioning to childcare. ...
... Based on the studies by Ahnert et al. (2004) and Bernard et al. (2015), we hypothesize that afternoon levels should be less elevated on the initial days in childcare accompanied by parents and then distinctly elevated in the afternoons compared with the mornings on the first days separated from parents and after four to six weeks in childcare. We hypothesize furthermore that cortisol levels will drop in the evening after children are picked up from childcare, as observed by Sumner, Bernard, and Dozier (2010) and Groeneveld et al. (2010). In addition, we want to study some basic child and childcare center variables and their influence on cortisol levels. ...
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Full-text available
In toddlers, the transition from home to childcare might elicit high levels of the stress hormone cortisol. Measuring cortisol may give an indicator for children’s experience and hence, may help improve this transition. We applied linear mixed model analyses to investigate the cortisol levels of 119 toddlers during their transition to childcare across time of day (morning, afternoon, and evening) and phase (accompanied by parents, separated from parents, and after four to six weeks in childcare). The influence of age, gender, number of siblings, and childcare group size was analyzed. Time of day and phase influenced cortisol levels significantly. On average, children had elevated cortisol levels in the afternoon throughout transition, with the peak coming in the separation phase. Cortisol levels declined significantly toward the evening. Children younger than 14 months showed higher evening levels and higher afternoon levels after 4–6 weeks in childcare. The findings suggest that the onset of childcare – particularly separation from parents – may be demanding for toddlers. Low evening levels indicate relief of tension at home. Higher levels of afternoon cortisol of under 14-months-old children at the follow-up measurement may indicate that younger children need more time to settle in at childcare.
... 44 ). Evidence suggests that within the hours in which the experiment was performed, time of day matters less for cortisol levels in children than it does for wake-up and bedtime 45,46 . In the current sample, there was no association between time of day and cortisol levels (r(76) P = −0.13, ...
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Full-text available
Attachment-related learning (that is, forming preferences for cues associated with the parent) defies the traditional rules of learning in that it seems to occur independently of apparent reinforcement¹—young children prefer cues associated with their parent, regardless of valence (rewarding or aversive), despite the diversity of parenting styles². This obligatory attraction for parental cues keeps the child nearby and safe to explore the environment; thus, it is critical for survival and sets the foundation for normal human cognitive–emotional behaviour. Here we examined the learning underlying this attraction in preschool-age children. Young children underwent an aversive conditioning procedure either in the parent’s presence or alone. We showed that despite disliking the aversive unconditioned stimulus, children exhibited a behavioural approach for conditioned stimuli that were acquired in the parent’s presence and an avoidance for stimuli acquired in the parent’s absence, an effect that was strongest among those with the lowest cortisol levels. The results suggest that learning systems during early childhood are constructed to permit modification by parental presence.
... Previous studies link elevated cortisol and obesity risk, 85 and ECE attendance has been associated with higher cortisol levels in children. 86,87 ...
Article
It is the position of the Academy of Nutrition and Dietetics that early care and education (ECE) programs should achieve recommended benchmarks to meet children's nutrition needs and promote children's optimal growth in safe and healthy environments. Children's dietary intake is influenced by a number of factors within ECE, including the nutritional quality of the foods and beverages served, the mealtime environments, and the interactions that take place between children and their care providers. Other important and related health behaviors that may influence the development of obesity include children's physical activity, sleep, and stress within child care. Recent efforts to promote healthy eating and improve other health behaviors in ECE include national, state, and local policy changes. In addition, a number of interventions have been developed in recent years to encourage healthy eating and help prevent obesity in young children in ECE. Members of the dietetics profession, including registered dietitian nutritionists and nutrition and dietetics technicians, registered, can work in partnership with ECE providers and parents to help promote healthy eating, increase physical activity, and address other important health behaviors of children in care. Providers and parents can serve as role models to support these healthy behaviors. This Position Paper presents current evidence and recommendations for nutrition in ECE and provides guidance for registered dietitian nutritionists; nutrition and dietetics technicians, registered; and other food and nutrition practitioners working with parents and child-care providers. This Position Paper targets children ages 2 to 5 years attending ECE programs and highlights opportunities to improve and enhance children's healthy eating while in care.
... Thus, the story appears to be that for infants, toddlers, and young preschoolers, being away from home and with other children all day produces elevations in cortisol by late afternoon and the presence of the child care provider does not seem to buffer this stress response. It is noteworthy that there is evidence that cortisol levels drop when parents pick the child up and are not different during the evening on child care and nonchild-care days (Sumner, Bernard, & Dozier, 2010). Together these data fail to provide any support for the idea that the child care provider is substituting for the parents as a stress buffer. ...
Article
This review provides a broad overview of my research group’s work on social buffering in human development in the context of the field. Much of the focus is on social buffering of the hypothalamic-pituitary-adrenocortical (HPA) system, one of the two major arms of the mammalian stress system. This focus reflects the centrality of the HPA system in research on social buffering in the fields of developmental psychobiology and developmental science. However, buffering of the cardiovascular and autonomic nervous system is also discussed. The central developmental question in this area derives from attachment theory, which argues that the infant’s experience of stress and arousal regulation in the context of her early attachment relationships is not an immature form of social buffering experienced in adulthood but rather the foundation out of which individual differences in the capacity to gain stress relief from social partners emerges. The emergence of social buffering in infancy, changes in social buffering throughout childhood and adolescence, the influence of early experience on later individual differences in social buffering, and critical gaps in our knowledge are described.
... [29][30][31][32][33][34] Napping during the day while children are in childcare may delay sleep onset at night 35 36 and decrease the duration and quality of night-time sleep. [37][38][39] Childcare outside of the home has been associated with greater stress in children in a number of prior studies, [40][41][42] and many previous studies have shown a potential link between elevated cortisol levels and obesity. 39 40 For the ongoing Nurture Study, we will assess the relationship between childcare and obesity and examine specific factors that may influence this relationship, especially the role of multiple caregivers, in a sample of children from birth to 12 months of age. ...
... [29][30][31][32][33][34] Napping during the day while children are in childcare may delay sleep onset at night 35 36 and decrease the duration and quality of night-time sleep. [37][38][39] Childcare outside of the home has been associated with greater stress in children in a number of prior studies, [40][41][42] and many previous studies have shown a potential link between elevated cortisol levels and obesity. 39 40 For the ongoing Nurture Study, we will assess the relationship between childcare and obesity and examine specific factors that may influence this relationship, especially the role of multiple caregivers, in a sample of children from birth to 12 months of age. ...
Article
Full-text available
Purpose Childcare has been associated with obesity in children in cross-sectional and longitudinal studies, although some observed no association. Few studies have focused on care during infancy, a period when children may be especially vulnerable. Participants The Nurture Study is an observational birth cohort designed to assess longitudinal associations of childcare and the presence of multiple caregivers on infant adiposity and weight trajectories throughout the first year of life. We examine as potential mediators feeding, physical activity, sleep and stress. We completed recruitment in 2015. Of the 860 women who enrolled during pregnancy, 799 delivered a single live infant who met our inclusion criteria. Of those, 666 mothers (77.4%) agreed to participate in the study for themselves and their infants. Findings to date Among the 666 women in the study, 472 (71%) identified as black, 127 (19%) as white, 7 (1%) as Asian or Asian American, 6 (1%) as Native American and 49 (7%) as other race or more than one race; 43 (7%) identified as Hispanic/Latina. Just under half (48%) had a high school diploma or less, 61% had household incomes <$20 000/year and 59% were married or living with a partner. The mean (SD) infant gestational age was 41.28 weeks (2.29) and birth weight for gestational age z-score was −0.31 (0.93). Just under half (49%) of infants were females, 69% received some human milk and 40% were exclusively breast fed at hospital discharge. Data collection began in 2013, is currently underway, and is scheduled to conclude in late 2016. Future plans Results will help assess the magnitude of associations between childcare in infancy and subsequent obesity. Findings will also inform intervention and policy efforts to improve childcare environments and help prevent obesity in settings where many infants spend time. Trial registration number Clinicaltrials.gov, NCT01788644.
Article
Elevated levels of the stress hormone cortisol have been found in toddlers in childcare. Measuring cortisol may provide an indication of children's experiences in childcare and help to adjust practices better to their needs. To the best of our knowledge, toddlers' cortisol levels in childcare have not yet been investigated longitudinally. Furthermore, it is unclear which child and childcare factors contribute to cortisol elevation in toddlers. Using linear mixed model analyses, we investigated the full-day cortisol activity (10.00 h, 15.00 h, 18.00 h) of 156 toddlers (81 female, 56 male) during a year in childcare (September, January, June). We also investigated child cortisol levels at home in January. In addition, we tested the relation between cortisol activity and changes in cortisol activity across the year and childcare quality, temperament, well-being in childcare, and maternal education. We found increasing evening cortisol levels through the year while controlling for age. Afternoon cortisol levels were stable, but above morning cortisol levels in September and January and only slightly below morning cortisol levels in June. At home in January, afternoon levels were significantly below morning levels. Higher well-being in childcare was associated with lower overall cortisol levels and less increase in evening cortisol levels through the year in childcare. Further, less active toddlers seemed to accumulate some stress during the childcare day, indicated by higher evening cortisol levels. Rising evening cortisol levels may indicate accumulating stress across the year. Results point toward childcare being demanding for toddlers and their need for consideration from caregivers and parents, also after a longer period of childcare attendance. The findings underline the importance of observing, promoting, and further researching children's well-being in childcare.
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Developmental programming of the hypothalamic–pituitary–adrenal axis is theorized as a mechanism through which early life experiences are linked to later health outcomes. Despite the importance of understanding early stress responses, reliably eliciting stress responses in young children can be challenging. The current study measured salivary cortisol reactivity in a diverse sample of preschoolers. A standardized challenge paradigm was administered at home and at child care for each child, allowing for comparison of normative cortisol reactivity between settings. Results demonstrated that administration at home was associated with significant cortisol reactivity, while administration at child care was not. In comparison to white children, racially and ethnically diverse children exhibited lower cortisol reactivity in response to the home stressor. Results suggest that home‐based stress paradigms may be particularly effective at eliciting a stress response in this age range. Possible interpretations of differences by child race/ethnicity are discussed. Highlights • Differential physiological responses to stress examined between home and childcare environments for a diverse sample of preschoolers. • Significant cortisol reactivity was elicited at home but not at childcare, suggesting that home visits create a novel, naturalistic stressor for young children. • Latinx and non‐Latinx minority children exhibited lower physiological reactivity in comparison to white children – cultural and methodological considerations are discussed.
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The decrease in responsiveness of the hypothalamic–pituitary–adrenocortical (HPA) system is marked over the first months of life. Seventy-eight healthy infants (44 girls), 7 to 15 weeks old, were given a laboratory mock physical examination. Salivary cortisol samples were collected pre- and postexamination and at home. Behavioral state during the examination and home sleep/wake activity were measured. Subjects younger than 11 weeks showed an increase in pre- to postexamination cortisol, while older subjects did not. Further, there was no decrease in behavioral distress to the examination with age. Infants who showed an early-morning peak (EMP) in home cortisol levels were significantly older and were likely to be those who slept through the night. However, the presence of an EMP was not associated with a lack of cortisol response to the examination. The decrease in cortisol responsiveness witnessed around the age of 3 months is presumably due to other processes associated with age, and not with the expression of the day–night rhythm in basal cortisol. © 1998 John Wiley & Sons, Inc. Dev Psychobiol 33: 327–337, 1998
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In this study, we examined a model that describes both direct and indirect pathways between children's temperament and activity of the hypothalamic–pituitary–adrenal (HPA) axis when children are in peer-group settings. We hypothesize that in peer-group settings both shy, inhibited and exuberant, undercontrolled children would exhibit higher cortisol levels, but these associations would operate through different pathways. Sociometric measures of peer rejection, salivary cortisol, and teacher reports of temperament were collected on 82 preschoolers. Children who were rejected by classmates had higher cortisol levels than the other children. The combination of Surgency and Poor Effortful Control (Effortful Control, reverse scored) was associated with elevated cortisol through a pathway mediated by aggressive interactions with peers and peer rejection. With the indirect path explained, the combination of Surgency and Poor Effortful Control also was directly and negatively associated with classroom cortisol levels. These results help explain why temperament associations with HPA activity have been variable and difficult to discern when children are assessed in peer-group contexts. In these contexts, both direct and indirect pathways between temperament and cortisol need to be examined. © 2003 Wiley Periodicals, Inc. Dev Psychobiol 43: 343–358, 2003.
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Children who enter foster care have usually experienced maltreatment as well as disruptions in relationships with primary caregivers. These children are at risk for a host of problematic outcomes. However, there are few evidence-based interventions that target foster children. This article presents preliminary data testing the effectiveness of an intervention, Attachment and Biobehavioral Catch-up, to target relationship formation in young children in the foster care system. Children were randomly assigned to the experimental intervention that was designed to enhance regulatory capabilities or to a control intervention. In both conditions, the foster parents received in-home training for 10 weekly sessions. Post-intervention measures were collected 1 month following the completion of the training. Outcome measures included children's diurnal production of cortisol (a stress hormone), and parent report of children's problem behaviors. Children in the experimental intervention group had lower cortisol values than children in the control intervention. Also, the experimental intervention parents reported fewer behavior problems for older versus younger foster children. Results provide preliminary evidence of the effectiveness of an intervention that targets children's regulatory capabilities and serve as an example of how interventions can effectively target foster children in the child welfare system.
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We reviewed nine studies in which children's cortisol levels at center daycare were assessed. Our first hypothesis, concerning intraindividual differences in cortisol levels across home and daycare settings, was also tested in a meta-analysis. Our main finding was that at daycare children display higher cortisol levels compared to the home setting. Diurnal patterns revealed significant increases from morning to afternoon, but at daycare only. The combined effect size for seven pertinent studies (n = 303) was r = .18 (CI .06–.29, p = .003). We examined all papers on possible associations between cortisol levels and quality of care, and the influences of age, gender, and children's temperament. Age appeared to be the most significant moderator of this relation. It was shown that the effect of daycare attendance on cortisol excretion was especially notable in children younger than 36 months. We speculate that children in center daycare show elevated cortisol levels because of their stressful interactions in a group setting.
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This study examined early observed parenting and child-care experiences in relation to functioning of the hypothalamic-pituitary-adrenocortical axis over the long term. Consistent with the attenuation hypothesis, individuals (n = 863) who experienced: (a) higher levels of maternal insensitivity and (b) more time in child-care centers in the first 3 years of life had lower awakening cortisol levels at age 15. Associations were small in magnitude. Nonetheless, results were (a) additive in that both higher levels of maternal insensitivity and more experience with center-based care uniquely (but not interactively) predicted lower awakening cortisol, (b) not accounted for by later caregiving experiences measured concurrently with awakening cortisol at age 15 or by early demographic variables, and (c) not moderated by sex or by difficult temperament.
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Changes in cortisol and behavioral responses were examined longitudinally in 83 infants (39 girls, 44 boys) tested at their well-baby exams with inoculations at 2, 4, 6, and 15 months (72 infants completed all testing). Another sample of 2-, 4-, and 6-month-olds (n = 18 per age) received mock exams without inoculations to determine early developmental changes to the exam procedures. Behavioral distress was coded every 30 sec during the exam, a 5-min inoculation period, and a 20-min recovery period. Salivary cortisol was obtained upon arrival at the clinic and 25 min after the beginning of the inoculation period. To the exam-inoculation procedures, cortisol responses were high at 2 months, decreased significantly between 2 and 4 months, remained comparable between 4 and 6 months, and then declined again between 6 and 15 months. Between 6 and 15 months there was also a decrease in pretest cortisol. By 15 months, significant increases in cortisol from pre- to posttest were no longer observed for most infants. To the exam-only procedures, cortisol responses decreased between 2 and 4 months, and by 4 months most infants failed to show pre- to posttest increases in cortisol. Behavioral distress decreased between 2 and 6 months, but increased again at 15 months. While crying and cortisol were modestly correlated during the 2- to 6-month exam-inoculation procedures, at 15 months no significant correlations were obtained. Behavioral and hormonal reactions thus followed different ontogenetic paths and may provide different information about infant functioning. There was some evidence that the emergence of the circadian rhythm in cortisol might be related to the early decrease in cortisol response.
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The relations between social behavior and daily patterns of a stress-sensitive hormone production were examined in preschool children (N = 75) attending center-based child care. Three behavioral dimensions, shy/anxious/internalizing, angry/aggressive/externalizing, and social competence, were assessed by teacher report and classroom observation, and their relations with 2 measures of cortisol activity, median (or typical) levels and reactivity (quartile range score between second and third quartile values) were explored. Cortisol-behavior relations differed by gender: significant associations were found for boys but not for girls. Specifically, for boys externalizing behavior was positively associated with cortisol reactivity, while internalizing behavior was negatively associated with median cortisol. Time of day of cortisol measurement affected the results. Surprisingly, median cortisol levels rose from morning to afternoon, a pattern opposite to that of the typical circadian rhythm of cortisol. This rise in cortisol over the day was positively correlated with internalizing behavior for boys. The methodological and theoretical implications of these findings for the study of the development of hormone-behavior relations are discussed.