The main reason for feeling dizzy when getting up is usually a sudden drop in blood pressure known as orthostatic hypotension (or postural hypotension). When standing up, gravity causes blood to pool in the legs, temporarily reducing blood flow to the brain, which causes dizziness. Normally, the nervous system compensates by increasing heart rate and constricting blood vessels to quickly restore blood pressure, but if this compensation is delayed or insufficient, dizziness occurs.
Common causes include:
- Dehydration, which reduces blood volume and can occur overnight.
- Medications that lower blood pressure.
- Heart problems or hormonal imbalances.
- Prolonged bed rest or aging effects on blood pressure regulation.
- Neurodegenerative diseases that affect autonomic nervous system function.
If dizziness happens mostly in the morning upon standing, dehydration and low blood sugar may also contribute.
If dizziness is frequent, severe, or associated with other symptoms like fainting, consulting a healthcare provider is important to rule out serious underlying conditions.
In summary, feeling dizzy when standing up is often due to orthostatic hypotension caused by a temporary drop in blood pressure and related factors like dehydration or medication use.
