The feeling of black out for a few seconds and dizziness
can be attributed to reduction in blood pressure on sudden getting up from bed owing to peripheral pooling of blood in legs.
The increase in heart rate
is a compensatory mechanism of the body to tackle this emergency.
1. Maintain adequate hydration & proper nutrition
2. While getting up from bed, rise gradually to prevent fall in blood pressure.
3. Avoid indulging in aggressive weight loss
4. Get blood pressure & blood sugar levels checked...so that any fluctuations from the normal values can be taken care of.
Wishing you a good health.
Thanks & take care