Seeing stars when standing up
Also called: Postural hypotension · Orthostatic hypotension · Head rush
You stand up fast, your vision goes grey or sparkly, and your head feels light for a few seconds. Blood has briefly pooled in your legs. It passes on its own.
How common
Does this happen to you?
These are answers from visitors, not a study.
How it works
Standing up moves 300 to 800 mL of blood from the chest into the legs, pulled by gravity1. Less blood returns to the heart. For a moment, blood pressure at the head drops. Pressure sensors in the neck arteries detect the drop and tell the heart to beat faster and the blood vessels to tighten. This is the baroreflex2. It takes a few seconds to catch up.
If the reflex is slow, the brain and the retina get slightly less blood for those seconds. The retina is very sensitive to this. It sends spots, sparkles, grey, or a closing tunnel of vision. These are phosphenes caused by reduced blood flow3. The ears may ring and the legs may feel weak. It usually passes within a few seconds to half a minute1.
It is worse when you are dehydrated, hot, hungry, or tired, after a hot bath, after standing still for a long time, after alcohol, or when you have been lying down for a while1. It is common in teenagers and young adults1.
Between 5% and 20% of people meet the clinical definition of orthostatic hypotension, a drop of 20 mmHg in the top blood pressure number within three minutes of standing1. Most of them are older adults1.
Is it a problem?
No, when it is brief. Sit or lie down and it passes. To prevent it, stand up slowly, drink enough water, and tense your leg muscles before you rise.
See a doctor if you actually faint, if it happens most times you stand, if it comes with chest pain, or if your heart races for minutes rather than seconds. Also see a doctor if it happens during exercise rather than after it. If you fall and hit your head, get checked.
Sources and further material
- Encyclopedia Orthostatic hypotension