A strange thing happened to one 73-year-old woman who came into an emergency room in Bern, Switzerland, in August 1997. The woman was having a stroke that affected an area deep in the back of her brain. She lost her vision and feeling in her left side temporarily, though everything returned to normal after a while. The odd thing was that, except for one night shortly after the stroke, she stopped dreaming. Swiss researchers examined the woman's brain to see if they could figure out why.

What they wanted to know: What made one woman stop dreaming after her stroke?

What they did: The woman recovered in the hospital for a month after her stroke, and some of the nights she was there the researchers hooked her up to machines that monitored her brain activity during sleep. When she entered a phase of sleep when people usually have dreams, called rapid eye movement or REM sleep, the researchers woke her up and asked her if she was dreaming. After she left the hospital, the researchers called her for a year to ask if she had dreams.

What they found: Before her stroke, the woman said, she used to have at least three dreams a week that she remembered the next morning. But after the stroke, she almost completely quit dreaming and the few dreams she had were not as intense as those that she had before the stroke. The researchers think that the inferior lingual gyrus, the area deep in the woman's brain that was damaged by the stroke and that helps normal brains process faces and landmarks, must be the place in the brain where dreams are created. No one had been able to pin that location down before, so their results are important. They also found that, even though the woman's dreams were interrupted, she still had rapid eye movement during sleep. Previously, scientists had thought that rapid eye movement and dreams came from the same area of the brain.

What it means to you: Well, if you've ever wondered where your bad dreams come from, blame your inferior lingual gyrus. These results should help scientists who study sleep and dreams to learn more about the still mysterious phenomenon.

Caveats: The researchers looked at the dreams of only one woman so they can't be sure that their results weren't a fluke, or that there was some other part of her brain that was damaged that they missed. Also, the inferior lingual gyrus could be just part of what makes a dream.

Find out more: The International Association for the Study of Dreams has a great deal of general information about dreams (http://www.asdreams.org) including a page with answers to frequently asked questions (http://www.asdreams.org/subidxeduq_and_a.htm).

If you're more into interpreting your dreams, try this site: www.dreammoods.com

Read the article: Bischof, M. and Bassetti, C.L. "Total Dream Loss: A Distinct Neuropsychological Dysfunction After Bilateral PCA Stroke." Annals of Neurology. Sept. 2004. Available online only.

Abstract online: http://www3.interscience.wiley.com/