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Cortisol Excretion Levels and Daytime Sleep in One-Year-Old Infants

Departments of Psychiatry and Pharmacology, University of Colorado School of Medicine Denver, Colorado 80220

Address for reprints: University of Colorado Medical Center, 4200 East Ninth Avenue, C264, Denver, Colorado 80220.

Urine was collected from 20 oneyear-old infants from the time of awakening in the morning for 8 consecutive h. Free cortisol was measured by competitive protein-binding analysis in each urine sample. The mean cortisol excretion rate for the entire collection period was .228 ± .019 βg/h/kg. The mean excretion rate of sleeprelated cortisol (1.86 ± .28 βg/h) was significantly different from the mean rate for awake periods (2.61 ± .28 βg/h). The difference could not be attributed to time of day. The results suggest a direct relationship between cortisol production and daytime sleep-wake states in the one-year-old.

Supported by USPHS, MIH Grant #23580, and by NIMH Research Scientist Development Award KO2 MH-42479 (to A. Vernadakis).

Received April 8, 1976.