For years I've had dizzy spells when I get up in the morning. I'm 20, and don't have any obvious medical problems. Sometimes while this is happening my vision gets spotty for a few seconds, then returns to normal. I don't think it's anything serious but would like to know what causes it.
When you stand up suddenly, all the blood in your body wants to sink down to your legs because of gravity. Your brain gets starved of blood momentarily.
Your body will increase your blood pressure by increasing the squeeze of your blood vessels and the pumping strength and your heart rate, but this takes a second or two. Because your brain needs so much oxygen, even transient decreases in blood flow result in it going offline. This manifests as fuzzy vision, or "greying out". People may feel lightheaded or unsteady on their feet momentarily. Very rarely, people may lose consciousness, but for most it's just some visual spots and a bit of swooning.
For most people - especially those who are young, thin and healthy - low blood pressure is a non-issue.
You just get up more slowly, and sit on the edge of the bed for a minute or two before standing up. That completely solves the problem for most people, by giving the heart and vessels time to adjust.
As you age your arteries will harden, and your blood pressure will rise, eliminating the problem of hypotension but, unfortunately, increasing the odds of the opposite, hypertension, which does carry health risks.
There are a rare few serious causes of chronically low blood pressure, often related to the side-effects of high blood pressure medication, or endocrine problems like low thyroid hormone. Your GP can easily sort this out. For most, however, low blood pressure can be considered a good thing, even if it's a little annoying at times.