Both a sleep-wakefulness cycle and a basic rest-activity cycle were observed in 20 normal infants left undisturbed for ten hours following birth. Behavioral wakefulness occurred immediately following delivery and in between sleep periods despite the lack of feeding and other intervention. Medication given to mothers during labor resulted in decreased amounts of infant wakefulness and increased amounts of quiet (non rapid eye movement) sleep.
Emde RN, Swedberg J, Suzuki B. Human Wakefulness and Biological Rhythms After Birth. Arch Gen Psychiatry. 1975;32(6):780–783. doi:10.1001/archpsyc.1975.01760240108008