1. https://pubmed.ncbi.nlm.nih.gov/16380706/
The circadian rhythm of tryptophan in breast milk affects the rhythms of 6-sulfatoxymelatonin and sleep in newborn.
2 Getting rhythm: how do babies do it?
https://pubmed.ncbi.nlm.nih.gov/25245173/#affiliation-2
https://fn.bmj.com/content/100/1/F50
3. Perspective: The Long-Term Effects of Light Exposure on Establishment of Newborn Circadian Rhythm
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6175794/
4. About sleep
https://raisingchildren.net.au/newborns/sleep/understanding-sleep/about-sleep
5. Sleep and Your Child
https://www.ucsfbenioffchildrens.org/education/sleep-and-your-child
6. How Your Baby's Sleep Cycle Differs From Your Own
https://www.sleepfoundation.org/baby-sleep/baby-sleep-cycle