What is the reason for a baby shaking their head at night?

Patient's question:

Detailed medical condition and consultation purpose: Nodding at night

Doctor's answer:

Calcium deficiency is one of the primary factors causing restless sleep in babies. Most mothers consider this. Calcium deficiency and reduced blood calcium levels can increase the excitability of the brain's vegetative nervous system, leading to night waking, night terrors, and nighttime restlessness in babies. The solution is to supplement the baby with calcium and vitamin D and increase sun exposure.
A. Calcium supplementation: 300-500mg of elemental calcium per day
B. Vitamin D supplementation: 400-800 IU per day