Why Does My Vision Go Black When I Stand Up?

What Happens to Blood Flow to Your Brain When You Stand Up?

When you stand, your brain sits high above your heart, and your blood pressure and the amount of blood your heart pumps both dip for a moment. A 2003 review explains that the brain's own blood flow controls, called cerebral autoregulation, can't respond to rapid pressure changes, so flow in the brain's arteries falls briefly on standing, "and therefore a feeling of lightheadedness that even healthy humans sometimes experience." The same review credits muscle activity, the muscle pump, with defending the blood volume returning to the heart, and notes that without it "even normal humans faint."

A consensus paper sets the line for an abnormal dip: a systolic drop of more than 40 mmHg within 15 seconds of standing. That drop is usually brief and resolves within 15 to 30 seconds. In our team's view, a faster heart rate on standing is the body's rescue for brain blood flow, and why your heart races when you stand up covers that response.

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Why Does Standing Affect Your Vision?

Blurred vision is one of the recognized symptoms of low brain blood flow on standing. The Bárány Society's diagnostic criteria for hemodynamic orthostatic dizziness, written to separate dizziness "due to global brain hypoperfusion" from other causes, list blurred vision alongside weakness, trouble concentrating and a racing heart, in episodes "triggered by arising or present during upright position, which subsides by sitting or lying down." The 2019 NIH consensus on POTS also lists blurred vision among the symptoms of standing that improve quickly once you lie back down.

A 1998 study describes orthostatic intolerance as a racing heart with symptoms that include blurred vision, and in 30 patients compared with 17 controls on a tilt table, blood flow velocity in the brain fell significantly more in the patients. Research hasn't settled exactly why vision is affected. Our team sees vision changes as one of the places the brain shows that its blood supply is slipping, and cerebral hypoperfusion: causes, symptoms and tests covers low brain blood flow as a whole.

Why Do I Get Tunnel Vision When Standing Up?

A 2025 study tracked eye movements in 15 people with POTS and 15 healthy controls, first lying flat and then tilted upright to 60 degrees. Upright, the POTS group made fewer and shorter fixations and fewer, smaller and slower saccades, the quick jumps your eyes make between targets. The drop happened mostly in the outer part of the visual field and "coincided with the occurrence of subjective visual symptoms."

The authors concluded that people with POTS explore the edges of their visual field less when upright, "potentially leading to tunnel vision." They proposed a position-dependent problem in the frontal eye field as the explanation, which remains a hypothesis. In our team's view, tunnel vision on standing can come from 2 directions: less blood reaching the brain, and eyes that stop scanning the edges. What part of the brain controls eye movements explains how our team tests the second one.

Is It POTS, Orthostatic Hypotension or Something Else?

It can be either, and timing tells them apart. Immediate orthostatic hypotension, still often called initial OH, is a large, brief pressure drop in the first 15 seconds. Classic orthostatic hypotension is a sustained pressure drop within 3 minutes of standing or tilt. POTS is a sustained heart rate rise within 10 minutes of standing with no orthostatic hypotension, together with frequent symptoms on standing for at least 3 months. A consensus panel's screening questions for orthostatic hypotension include "Do you have vision disturbances when standing?"

Our team frames the difference this way: in POTS, the heart's rescue works hard enough to hold pressure up, and in orthostatic hypotension the rescue falls short and pressure itself falls. POTS vs orthostatic hypotension compares the 2 in full.

When Is Vision Loss on Standing an Emergency?

Sudden vision loss in one eye is a different pattern. Retinal ischemia is part of the American Heart Association's definition of a transient ischemic attack (TIA): "a transient episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischemia, without acute infarction," and the statement adds, "Patients with TIAs are at high risk of early stroke." That's why one-eye vision loss is treated as an emergency, even when it clears. Call emergency services for vision loss with weakness, numbness, a drooping face, trouble speaking, chest pain or shortness of breath.

If your vision starts to go dark, sit or lie down right away. Outside the features above, see a doctor promptly if your vision goes dark most times you stand, if you've fallen, or if the episodes are getting more frequent.

How Do You Test for Vision Going Black When Standing?

The test depends on when the drop happens. Immediate OH lasts seconds, and a 2007 review states that "only continuous beat-to-beat BP measurement during an active standing-up manoeuvre can document this condition," because it comes with actively rising and "passive tilting is of no diagnostic value." Classic OH and POTS build over minutes and show up on a stand test or a tilt table test. Blood pressure and heart rate leave out the brain itself, so transcranial Doppler measures blood flow velocity in the brain's arteries, the same measure used in the 1998 orthostatic intolerance study. When brain blood flow falls on standing while heart rate and blood pressure stay within normal limits, that's OCHOS, and orthostatic cerebral hypoperfusion syndrome covers how it's found.

Our team tests how blood pressure, heart rate, breathing and brain blood flow respond when you stand, to find where the system falls behind. Medications can help and can serve as a bridge while the regulation problem is addressed, though they have a ceiling: midodrine is FDA-approved for symptomatic orthostatic hypotension and droxidopa for neurogenic orthostatic hypotension. A consensus panel on neurogenic orthostatic hypotension set the treatment goal as fewer symptoms, especially falls, and longer standing time, and said treatment shouldn't aim for a normal standing pressure. In our team's view, medications hold pressure up while the regulation underneath stays where it was. Our team leaves existing medications alone initially and doesn't advise changes; that's the prescriber's call.

Vision Going Black When Standing: FAQ