The Effects of Morning Naps, Car Trips, and Maternal Separation on Adrenocortical Activity in Human Infants
The authors of the journal The Effects of Morning Naps, Car Trips, and Maternal Separation on Adrenocortical Activity in Human Infants had two objectives of their study. First, they wanted to find out why car trips lowered baseline cortisol. Second, was the baseline cortisol increase during separation stress-triggered or merely a rebound to its home level? They based their study research on past contradicting findings from free-flowing saliva samples. Some results reflected their expectations of stressful stimulations elevating cortisol levels. Some proved that infants rapidly adapted to repeated behavioral-distress exposures, thus resulting in a negative cortisol correlation. Others reported that irritability reflected lower cortisol concentrations. To prove their objectives, Larson, Gunnar, and Hertsgaard conducted three studies.
The first study employed 13 girls and 11 boys aged 8.1 to 11.2 months. Parents collected saliva samples before the infants slept, immediately they woke up and forty-five minutes after waking up to show the effects of napping. Cortisol was assayed. After a combination of results from both genders, a negative correlation after forty-five from waking up was obtained. The second study used sixteen female and ten male infants aged 8.6 to 10.7 months. Study one affected study two because it affected the time of collecting the infants’ saliva samples after waking up. The parents took the samples before leaving home, immediately they got to the laboratory after the drive and forty-five minutes post the drive. Cortisol levels were analyzed, and outlier levels were scanned for. Considering the babies’ behaviors in the car during the drive, whether calm or fussy, asleep or awake, among others, cortisol levels against behavior were studied. The results showed that car trips significantly reduced cortisol levels. Finally, the third study used 12 male and 12 female infants for nonseparation, and 15 female and 12 male infants for separation conditions aged 8.6 to 10.3 months. After fifteen minutes of arrival at the laboratory, saliva samples were obtained for both groups. In the nonseparete cohort, the experimenter left while in the separate, the mother left. Thirty minutes after the experiment, the samples were taken. After analysis, the separate cohort, there was a positive correlation between the activities and cortisol levels, while in nonseparate, there was no significant correlation. They concluded that situations that did not produce stress-elevated cortisol, there was a nonsignificant correlation between cortisol and behavior. However, the time factor was problematic due to individual differences, which affected the consistency in data.