When you stand, gravity pulls blood toward your legs, and your body normally adjusts within seconds. If that adjustment lags, blood pressure briefly drops and you feel dizzy — this is orthostatic hypotension. Common contributors include dehydration, hot weather, alcohol, prolonged bed rest, pregnancy, and medicines such as some blood-pressure tablets, diuretics, or antidepressants.
Simple steps help: stand up slowly, sit on the edge of the bed before getting up, stay well hydrated, and avoid sudden position changes. If it happens often, causes near-fainting or falls, or you actually pass out, see a doctor, as it may relate to anemia, heart problems, blood sugar, or medication that needs reviewing.
Seek urgent care if you faint and injure yourself, have chest pain or palpitations, or the dizziness comes with stroke-like symptoms. Do not stop prescribed medicines without speaking to your clinician. Informational only.