DEAR DR. ROACH: My doctor started me on Wellbutrin 150 mg XL for depression, but I have had terrible insomnia. She said it would get better in two to four weeks, but I am having severe anxiety due to not sleeping. Do you have any suggestions? — N.M.N.

ANSWER: Bupropion (Wellbutrin) is an antidepression medicine in another kind of class from medicines like Prozac or Celexa, which are SSRIs and have a very different side-effect profile. Bupropion seldom causes the sexual side effects often noted with SSRIs, and more often causes weight loss than weight gain.

However, bupropion must be used with extreme caution or not at all in people with a seizure disorder. Other side effects include dry mouth, nausea or dizziness, and your doctor is right that most often these will go away within the two to four weeks she mentioned.

Insomnia can be a real problem. The dose of 150 mg is better tolerated than 300 mg, and the XL formulation also tends to reduce side effects. However, in some people, enough of the medicine is left in the system to make it hard to sleep. In that case, one approach is to use a smaller dose of the shorter-acting formulation while the person is getting used to the medication. Behavioral treatments to help sleep — getting regular exercise (but not right before bed), avoiding bright lights and computer or television screens before bed, and avoiding caffeine after noon — may certainly help and are worth trying.

Finally, people who have some anxiety with depression may not do well with bupropion, because it does tend to be stimulating. People with depression and fatigue, and excess sleeping are excellent candidates for bupropion.

DEAR DR. ROACH: Why are stress tests no longer done on a treadmill? I was quite concerned when my last stress test was a nuclear stress test rather than on the treadmill. — M.E.

ANSWER: Stress tests are mainly used to diagnose blockages in the arteries of the heart. There are many different types of stress tests, but all of them stress the heart, and then look at the heart for any blockages.

Stressing the heart is traditionally done via exercise. On a treadmill or bike, a person exercises, starting off at low effort then building up in intensity until the person can’t continue. The most common protocol is called a Bruce protocol on the treadmill, and it gives important prognostic information as well as diagnostic: If you can’t complete three minutes on a Bruce protocol, that’s a very worrisome sign, but if you can keep going after nine minutes, you have a good prognosis EVEN IF you have blockages.

If a person cannot exercise, usually due to orthopedic or neurological disease, then a pharmacologic stress test is prescribed, using medications to speed up the heart rate, for example. This does not allow for the prognostic ability of finding how much exercise a person can tolerate, and it takes some time for the drugs to wear off.

The heart is always evaluated by the electrocardiogram, but doctors may also use radioactive isotopes to demonstrate blood flow in the heart. The advantage of a nuclear stress test is both better ability to make the diagnosis (sensitivity) and fewer false positives (specificity), but it costs a lot more and exposes the person to some radiation. An echocardiogram allows a doctor to see the heart without using radiation. It is an alternative to a nuclear stress test.

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Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or send mail to 628 Virginia Dr., Orlando, FL 32803.