What should I do if the child doesn't sleep?

Patient's question:

Doctor. My child is now 37 days old. The past two days, he hasn't been sleeping well during naps. The main symptom is that he can stay awake for a while when held, but as soon as he's put in bed, he wakes up after just two or three minutes. Could you help me make a guess? Thank you

Doctor's answer:

Dear consultant,
According to your description, the baby can sleep when held, which may be due to the baby being uncomfortable in a deep sleep environment, or it could be that the baby lacks a sense of security, or it might be a deficiency in vitamin D. I hope my explanation helps you.
The above is the suggestion for the question "Doctor. My child is now 37 days old." I hope it is helpful to you. Wishing you good health!