Brief Answer:
See the description

Detailed Answer:
hello,
Does it occurs on standing especially while getting up from sitting or sleeping position, is there associated palpitations etc.
It's most probably a orthostatic hypotension. It's a condition where bp transiently falls after standing or assuming erect posture leading to decreased blood supply to brain and fainting. Occurs due to autonomic neuropathy, causes may be Diabetes, drugs, aging etc. To confirm this, we need to take sleeping bp and blood pressure after standing either after development of symptoms or after 3 min whichever is earlier, then comparison of two readings. You get your blood pressure checked and if its not on higher side, say more than 130/80 then you need to increase salt and water intake and some behavioral changes like avoid sudden assumption of erect posture, and arising slowly, in stages, from supine to seated to standing. This maneuver is most important in the morning, when orthostatic tolerance is lowest and one gets symptoms. Raising the head of the bed 10 to 20 degrees will also help. We can also discuss some more measures if these are not helpful.
Also, get your pulse rate examined, if it's low then it can also be a reason.
If above doesn't help then you will need some tests like carotid artery Doppler to see whether there is narrowing of carotid arteries supplying blood to the brain, ecg and also echo.
So get above things done, try to think of factors which causes or increases symptoms and which decreases the symptoms. Get back with some information like bp, pulse rate and have any doubts.

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