Scientists may have found an answer to what makes placebos, sugar pills with no therapeutic or curative value, work.
People who suffer from a mild infection recover, whether they take a medicinal drug or a placebo, which shows that humans can heal themselves. But this has begged the question why people need to wait for the placebo before the recovery process from an infection begins.
Researchers have now found that something similar to the placebo effect occurs in animals, after studying Siberian hamsters. The placebo effect is the measurable, observable, or felt improvement in health or behaviour not attributable to a medication or invasive treatment that has been administered.
For instance, if lights above the hamsters lab cages mimicked winter, they found the hamsters would not fight the infection. However, if the lighting was changed to replicate summer conditions, the hamsters mounted a full immune response, the "Daily Mail", quoting the "New Scientist", reported.
Similarly, people who think they are taking medicine to treat an illness, but are actually receiving a placebo, can see a response from their immune system twice that of people who take no pills.
The evidence shows that intervention activates a mental response which triggers the immune system into action, says Peter Trimmer, biologist at the University of Bristol.
Trimmer suggests that the immune system uses up plenty of energy when it is in action. So an animal's energy reserves could be severely depleted if the immune system launches a long response to an illness.
If the infection is not likely to cause death, it could be better to wait and see that fighting the illness does not expose the animal to other danger. Evidence from a computer model designed by Trimmer and his colleagues now supports this evidence.
The researchers found that animals which live in challenging environments where food was harder to find, lived longer if they put up with infections rather than launch a response from their immune system.
However, for those animals living in much more favourable conditions, it was better for them to launch a response from their immune systems so they return to health quicker. In better conditions, they have more access to food which provides energy to sustain an immune response.