TY - JOUR
T1 - Disentangling sources of individual differences in diurnal salivary α-amylase
T2 - Reliability, stability and sensitivity to context
AU - Out, Dorothée
AU - Granger, Douglas A.
AU - Sephton, Sandra E.
AU - Segerstrom, Suzanne C.
N1 - Funding Information:
DO was supported by a Rubicon award ( 446-10-026 ) from the Netherlands Organization for Scientific Research .
PY - 2013/3
Y1 - 2013/3
N2 - In the present study, we employ a longitudinal design and a generalizability framework to examine the sources of variance in the diurnal rhythm of salivary α-amylase (sAA). The sample consisted of 122 first-year law students (55% male, mean age = 23.9 years), who collected five saliva samples on each of three consecutive days at each of five data collection waves. In total, over 6900 saliva samples were collected, which allowed us to examine the properties of diurnal variation in sAA in great detail. Systematic individual differences accounted for 15-29% of the variability in the awakening response and diurnal slope, and for 61-65% of the variation in overall daily levels (i.e., diurnal mean, area under the curve with respect to ground [AUCg]). Although less than 1% of the variation was due to differences between waves and between days, the generalizability analyses revealed that between 16% and 17% of the variance in the diurnal mean, slope and AUCg is due to person by wave interactions, indicating that individuals vary in their biological sensitivity to environmental influences. In sum, this study documents sufficient stability and variation in diurnal sAA to warrant future studies on the origins and consequences of alterations in the diurnal rhythm of sAA worthwhile, and proposes guidelines on obtaining reliable measures.
AB - In the present study, we employ a longitudinal design and a generalizability framework to examine the sources of variance in the diurnal rhythm of salivary α-amylase (sAA). The sample consisted of 122 first-year law students (55% male, mean age = 23.9 years), who collected five saliva samples on each of three consecutive days at each of five data collection waves. In total, over 6900 saliva samples were collected, which allowed us to examine the properties of diurnal variation in sAA in great detail. Systematic individual differences accounted for 15-29% of the variability in the awakening response and diurnal slope, and for 61-65% of the variation in overall daily levels (i.e., diurnal mean, area under the curve with respect to ground [AUCg]). Although less than 1% of the variation was due to differences between waves and between days, the generalizability analyses revealed that between 16% and 17% of the variance in the diurnal mean, slope and AUCg is due to person by wave interactions, indicating that individuals vary in their biological sensitivity to environmental influences. In sum, this study documents sufficient stability and variation in diurnal sAA to warrant future studies on the origins and consequences of alterations in the diurnal rhythm of sAA worthwhile, and proposes guidelines on obtaining reliable measures.
KW - Diurnal
KW - Individual differences
KW - Reliability
KW - Salivary α-amylase
KW - Sensitivity to context
KW - Stability
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U2 - 10.1016/j.psyneuen.2012.06.013
DO - 10.1016/j.psyneuen.2012.06.013
M3 - Article
C2 - 22819683
AN - SCOPUS:84875261860
VL - 38
SP - 367
EP - 375
JO - Psychoneuroendocrinology
JF - Psychoneuroendocrinology
SN - 0306-4530
IS - 3
ER -