Dizziness happens when your brain receives conflicting or erroneous messages from your eyes, ears or nervous system regarding your body's place in your surroundings. While it happens most often when you are standing or moving, some types and causes of dizziness can occur when you are seated, especially those related to inner ear disturbances.
There are several types of dizziness, but vertigo and lightheadedness can both hit when you are sitting down. Vertigo is a feeling like you are moving when you are not, according to the Merck Manual of Health & Aging, and a common variation of this, benign positional vertigo, or BPV, occurs when you move your head. Lightheadedness, or presyncope, is defined as the sensation that you are about to faint, according to MayoClinic.com.
Vertigo is usually caused by an inner ear disturbance when nerves there send messages to your brain that don't mesh with what your eyes and body are telling it, according to Patient UK. If small particles normally present in the fluid of the inner ear become clumped when you move your head, BPV results. Meniere's disease, which involves too much fluid in the inner ear, can cause severe and prolonged spells of vertigo or BPV, up to half an hour, according to MayoClinic.com.
General lightheadedness that occurs when you are seated can be the result of your blood pressure dropping abruptly for some reason, such as if you just ate a large, heavy meal or if you have taken medication for high blood pressure. Other possible causes include anemia, high or low blood sugar or an underactive thyroid gland. An abnormal hearth rhythm that suddenly affects the amount of blood getting to your brain can also cause lightheadedness.
The Merck Manual of Health & Aging indicates that nausea and vomiting can sometimes accompany severe vertigo, as can nystagmus, which is a name for abnormal jerky eye movements. Nystagmus is usually an indication of an inner ear disorder. Vertigo can occur simultaneously with temporary hearing loss or tinnitus, as well, according to MayoClinic.com. Presyncope might be accompanied clamminess and nausea.
If you are pregnant and you experience dizziness while seated, it could have nothing to do with your inner ear or other likely causes. According to maternal child health nurse Beth M. Iovinelli, if you lean back while you are sitting down, your vena cava, the artery that transports blood from your lower body to your heart, can become compressed by your growing uterus. This can cause a brief spell of dizziness until you sit upright again.
Vertigo might worsen if you remain in a seated position, so lie down until the episode passes. If you are prone to dizzy spells, you should avoid any over-the-counter medications that cite dizziness as a possible side effect, such as antihistamines or sleeping aids. Caffeine, tobacco and alcohol can also intensify dizzy spells. If you regularly experience dizziness when you are not on your feet, you should consult your doctor to find out why, especially if the spells are accompanied by a headache unlike any you have experienced before, a stiff neck, a change in your vision, difficulty speaking or chest pain, advises MayoClinic.com.