From VOA Learning English, this is the Health Report.

Ketamine is a drug that puts people and animals into a deep sleep. Doctors inject it into patients so they can be operated on. Unofficially, Ketamine is a street drug, which means it is sold and used illegally. However, Ketamine may prove useful as a medicine to treat sickness too.

A new study shows the drug may help people who suffer from depression. Researchers in Britain studied 28 patients suffering from severe depression. Some of them reported feeling better, like a weight had been lifted from them soon after receiving injections of the drug.

Rupert McShane led the study. He says eights of the 28 patients injected got good results. Doctor McShane reported that three of those eights said they felt better just hours after getting one injection of Ketamine.

"Typically by about six hours, people are saying, 'Gosh, I am feeling like a weight is lifted from me. I can think more freely.'" he said.

The drug's apparent effects lasted one to six months. Researchers are looking for ways to make these effects last longer.

Researchers in the United States have carried out 6 larger studies on Ketamine and depression. They found the drug to be helpful in quickly easing the effects of depression that are usually difficult to treat.

Carlos Zarate is a researcher with U.S. National Institute of Mental Health. He says there are 30 different kinds of antidepressant drugs on the market. But he says, they do not help all the signs of depression.

One drug may help the extreme tiredness that can come with depression. However, the same drug may not ease the feelings of deep sadness. Another drug may improve a depressed person's ability to think clearly, but it may not help stop thoughts of suicide.

So Mr Zarate says most depression patients are treated with more than one drug. The reason Ketamine is so effective could be that it goes directly to a brain chemical linked to depression. He says traditional antidepressants target that chemical only indirectly.

"What takes about a couple of hours with ketamine [which] would take approximately six weeks with our standard antidepressants," said Zarate.

Research is now focused on how to safely treat patients with Ketamine, and how to make them feel better longer.

The British study of Ketamine was published in the Journal of Psychopharmacology. Psycho meaning dealing with the mind, pharmacology meaning the study of drugs. Psychopharmacology is the study of drugs on the mind.

And that's the Health Report from VOA Learning English. I'm Anna Matteo.