Brief Answer:
Possibly due to postural hypotension.

Detailed Answer:
Thanks for asking on HealthcareMagic.

I have gone carefully through your query. Your complaint could be due to postural hypotension. In simpler terms, when you wake up and sit up, the blood flow to the brain suddenly drops and you get the spinning sensation. When you are in lying position, the heart and the brain are in the same level and blood flow is easy and smooth. But as you sit up, the brain goes into a higher level and if the heart does not catch up immediately you get this postural hypotension.

I would insist you to get your blood pressure checked. Also drink plenty of water.

Let me know and I would guide you further.

Regards

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