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The doppler ultrasound (Leg) and blood tests have confirmed that your blood supply of your legs are intact, hence there should be no major issues.
The cause of sensory changes like transient numbness, tingling or temporary paralysis that you might be having could be due to pressure on the nerves or blood vessels possibly due to abnormal sleeping positions, eg. Sleeping with the hand under the head, keeping the hands above the level of the heart, sleeping in abnormal leg positions, etc.
In such situations, there is no need for specific treatment other than proper sleep hygiene and avoiding sleeping with the hand under the head, or with arms on the pillow.
In addition trying weight reduction via active lifestyle, regular exercises and diet control might help over the long term.
In case, you still have doubts, you might consult with a neurologist for a examination and tests including nerve conduction tests and MRI of the spine to rule out conditions like disc prolapse associated with degenerative joint diseases of the lower spine. Other conditions like hypothyroidism which can cause weight gain and abnormal sensory changes might also need to be ruled out.
I hope this helps.