Could my dizzy spells be caused by melatonin?

Q. At least once a week I experience a bout of extreme dizziness. It is accompanied by a physical feeling of being turned upside down, and everything looks upside down and blurred to me. It is very sudden and random. My body feels very heavy when this happens, like I'm on the kind of amusement park ride that pushes you backwards in your seat. My mother suggested it could be linked to the supplement melatonin. I take 5 mg of sublingual melatonin a night to help me sleep. Have you ever heard of melatonin causing this type of dizziness?

A. When a person uses the term "dizzy" to describe a symptom, it can reflect several different sensations. It may mean that the person is

• feeling lightheaded, especially upon standing up
• experiencing vertigo
• feeling detached and "out of it" - what I often refer to as "cobwebs inside the head."

The episodes of extreme dizziness you describe are most consistent with vertigo.

Usually the symptoms of vertigo are not this intense. More often, people with vertigo experience a sensation that the room is spinning or that you are spinning in the room. Sometimes it is just a sense of imbalance. Vertigo may be associated with nausea, vomiting, and ringing in one or both ears (tinnitus).

In general, melatonin is considered to be a relatively safe supplement for short-term use. There are reports of balance and equilibrium problems at higher doses, usually more than 5 milligrams per day. While it is not likely that the melatonin is causing the episodic vertigo, the only way to know if it is contributing is to stop taking it.

When a person has recurrent episodes of vertigo, I usually suspect a disorder called benign position vertigo (BPV). In this condition, a change in head position causes sudden episodes of a spinning sensation. BPV is caused by small crystals that break loose in the canals of the inner ear and touch the sensitive nerve endings inside.

Another potential cause of episodic vertigo is Menière's disease. But Menière's does not usually cause vertigo to happen as frequently as once a week. Also, the vertigo of Menière's is accompanied by ringing in the ear and some hearing loss.

A much rarer cause of recurrent vertigo is intermittent interruption of blood flow to the back part of the brain.

Your next step should be to talk with your doctor about your symptoms. If this is benign positional vertigo, your doctor may advise the Epley maneuver. This involves moving the head in a sequence of positions that directs the floating crystals into a part of the inner ear with fewer nerve endings.