Does a newborn baby have a circadian clock?

From the perspective of a chronobiologist consider:

Does a newborn baby have a circadian clock?

Is a newborn clock different from an adult clock?

Physiologically, how might these differences be explained?

Are these differences found across species or only in humans?

-: Clearly state the problem, give relevant background information

-Question: Main question was summarized and a the methods used and options considered were
described in sufficient detail, presented results clearly

Data: Data was thoroughly analyzed and was used to support the solution given

Conclusion: Summarized results, discussed possible explanations for results, pointed out errors or inconsistencies, discussed possible implications