Every time i bend over to pick something up or from doing something i get extremely light heading to the point of sitting down what could be the cause?

Volume issues: The veins in your lower extremities contain a significant portion of your total blood volume. Being bent over or sitting removes the need for your leg veins to keep tone up ; may relax and let the blood pool.Standing up changes the hydraulic pressure in your blood vessels and may leave you light headed. This can happen with blood pressure issues or poor fluid intake.See your doc for an eval.

Postural hypotension: Bending over may cause hypotension where it takes for your blood to reach your brain.

Low blood pressure: Positional changes, especially from a prolonged stooped position, to a sudden upright position may provoke a vaso-vagal response causing a faint feeling, dizziness, or lightheaded ness. Other condition can be inner ear disturbance resulting in dizziness as a result of changing positions rather suddenly. Anemia ; other possibilities exist. The above should be evaluated by your physician.