Reliability of salivary cortisol levels in toddlers

The choice of cortisol sampling times in early childhood studies varies widely. Given that recommendations on protocols are largely based adults, the present study aimed to broaden current knowledge by examining how reliably measures obtained at different daytimes would reveal between-individual differences toddlers’ levels. Parents were instructed take 10 saliva samples consecutively (five per day) from their toddler (N = 19; Mage 15.8 months, SDage 4.2 months). Intra-class correlations (ICCs) computed evaluate reliability. Cortisol taken morning between 30 and 80 min after awakening bedtime most reliable differentiating children (ICCs ? .80). Wake-up within first afternoon showed moderate reliabilities .64), whereas reliability noon was poor (ICC .43). Therefore, when investigating young while being restricted a few only, assessing (at least awakening) be advisable.