I got that dizziness a few weeks ago (almost blacked out when standing up)and it was because my blood pressure was down to 87/60 (normally about 120/80). It can happen if you get up fast, or for other reasons that make the blood move downwards (such as going to the bathroom). Being high apparently makes it worse.
Be sure you eat enough, drink plenty of water, and get enough sleep - whether you smoke or not.