Hi, thanks for writing to HCM.
Based on the description of symptoms, I suspect Positional head numbness
as the causative factor. At times during certain positions of sitting or sleeping blood flow is restricted through the artery
in the neck thereby decreasing circulation to the head and causing head numbness. Simply changing the position of the head and neck will resolve the issue.
There are many other causes that may produce headnumbness for which a detailed clinical examination by a Neurophysician is mandatory.
Hope this information is helpful. Good day