Why You Get Dizzy or Lightheaded When You Stand Up

If you exercise often and are in good shape you might occasionally experience dizziness and lightheadedness when you stand up quickly. This is generally nothing serious. Here are five common reasons for dizziness, and signs that your dizziness may be due to a more serious issue.

1. Post-Exercise Dizziness

Cardiovascular exercise makes your heart stronger and a stronger heart has a larger stroke volume.

That is, the amount of blood pumped out during each beat is greater, so the heart doesn't have to beat as often. A slow pulse rate is an indication of a strong, healthy heart. However, a slow heart rate can sometimes lead to dizziness when you change position. You may dizzy after exercise as your heart slows down drastically. A longer cool down period and a slow and steady walk should get you back on track as the dizziness dissipates.

2. Dizziness After Skipping Meals 

Low blood sugar can also cause dizziness. If you skip meals, low blood sugar can lower your mood and energy and result in lightheadedness. Keep your blood sugar balanced by eating meals and snacks regularly, usually every three hours to stave off dizziness due to skipping meals. If you are eating regularly and not skipping meals, yet still experiencing signs of low blood sugar, a more serious condition associated with low blood sugar, such as diabetes or hypoglycemia could be a possibility.

3. Low Blood Pressure

When you stand up quickly gravity pulls blood from your brain towards your feet and blood doesn't return to the brain until the next heartbeat. With a slow pulse, this takes a second or two and that is enough time to feel the lack of oxygen in the symptom of lightheadedness or dizziness.

It is also related to something called postural hypotension, which is more common in people over age 65. This results from a decrease in blood flow to the brain, due to a drop in blood pressure upon standing up. If you have a slow pulse (50 or less) and experience dizziness when standing up, try getting up more slowly and see if that solves the problem.

4. Dizziness Due to Dehydration and Overheating

Dehydration is another common cause of dizziness. Insufficient water in the body can cause blood flow to slow down. Dehydration undermines the body's ability to process normal functions and because blood is 80 percent water, blood pressure is lower if you're dehydration. If your urine is dark yellow, has a pinkish tint like chardonnay, or is orange, you may be dehydrated. Stop exercising and drink water or sports drink.

Overheating (hyperthermia) due to exercise, hot weather, or medications can also cause dizziness. Overheating can come on suddenly or develop over a longer time period. Either way, if you sweat profusely, or feel like you have a fever not associated with cold or flu symptoms, get help immediately. Stop exercise, move to a cooler environment, and use cold compresses on your neck.

If due to hot temperatures, you may be developing heat exhaustion or heat stroke.

5. Vertigo and Dizziness Due to Inner Ear Issues

If the room seems to be spinning or you seem to be moving while standing still, you may have an inner ear issue. Called vertigo, this is a serious condition that needs medical attention to correct. Inner ear changes due to age, ear infection or sudden changes in ear fluid are the major causes of vertigo.

When to See a Doctor

As long as your dizziness occurs only occasionally, you don't really need to worry. However, if you have constant and severe dizziness with changing position you should see a doctor to rule out an underlying condition such as an irregular heartbeat, anemia, ulcers, anxiety, or other medical conditions.

Sources:

Dizzy Spells When You Stand up: When Should You Worry? Harvard Health Publishing. https://www.health.harvard.edu/heart-health/dizzy-spells-when-you-stand-up-when-should-you-worry.

Higginson LAJ. Dizziness or LIght-Headedness When Standing Up. Merck Manual Consumer Version. https://www.merckmanuals.com/home/heart-and-blood-vessel-disorders/symptoms-of-heart-and-blood-vessel-disorders/dizziness-or-light-headedness-when-standing-up#.