Dear Dr. Gott: Once in a while, my body will "jerk" involuntarily as I fall asleep. What causes this? Does it mean I have a heart condition or other problem?

Reply: You appear to be describing a type of myoclonus. These sudden, involuntary muscle twitches are most often a symptom of an underlying disorder, some of which are more serious than others. Of the more than eight forms of myoclonus, potential causes range from Restless Legs Syndrome (RLS) to multiple sclerosis, Parkinson's and epilepsy.

Based on your brief note, I cannot give detailed information about a diagnosis but suspect you are suffering from sleep myoclonus. This form is characterised by twitches of a muscle or group of muscles that occur during the initial phases of sleep, most often at the moment of dropping off to sleep. Most people with this type of myoclonus don't require treatment but should be examined by a physician to determine whether there is an underlying cause.

Because you don't give an age or gender, I cannot give specific advice with regard to testing, but I recommend you discuss the situation with your physician. Be sure to tell him or her about the frequency, severity, immediate preceding events (such as whether there was a loud noise, flash of light, etc., just before the jerk) and how long you have been experiencing the symptom. Because of the possibility of RLS, a sleep study may be beneficial.

If your physician is uncomfortable ordering testing and attempting a diagnosis, request a referral to a neurologist, who should be familiar with the symptom.

To provide related information, I am sending you a copy of my Health Report "Sleep/Wake Disorders". Other readers who would like a copy should send a self-addressed stamped number 10 envelope and a cheque or money order for $2 to Newsletter, PO Box 167, Wickliffe, Ohio 44092. Be sure to mention the title.

Dear Dr. Gott: I am a 58-year-old widow. Recently, my regular doctor retired, so I went to a new one for my yearly mammogram. As the doctor was examining my breast, he told me that he found a lump and asked me if I had felt it during my self-exams. I hadn't. He sent me to get the mammogram, but nothing was found, so I was then sent for an ultrasound. Again, nothing was found, and the technician also did a manual exam and found nothing. When I returned to the doctor, he said I needed further testing, and, when I asked why, he said, "Because I definitely feel a pea-size lump, and it needs to be taken care of."

My insurance has paid only one-third of the costs incurred, and I cannot afford any more tests at this time. Why would my doctor want me to have more tests when I, both tests and the sonogram tech can't find anything abnormal? This has been a scary and costly experience. What should I do?

Reply: You are in a bind. On one hand, you may have early breast cancer. But on the other, you may not and will have wasted a significant amount of money. I take breast cancer very seriously. One reason is that the disease usually responds well to therapy if diagnosed in its early stages.

Your best course of action is to obtain a second opinion from a surgeon who is especially experienced in treating breast lesions. If the surgeon cannot feel the breast lump, he or she may suggest holding off and retesting you in three or six months. If everything continues to appear normal, resume your yearly mammograms and follow your doctor's suggestions.

Dr. Peter Gott is a retired physician and the author of 'Dr. Gott's No Flour, No Sugar Diet' and 'Dr. Gott's No Flour, No Sugar Cookbook'. Contact him c/o United Media, 200 Madison Avenue, fourth floor, New York, New York 10016.