Happiness can affect your genes in a healthy or unhealthy way depending on what causes you to feel pleasure, a first-of-its-kind study has found.

US researchers found that human bodies recognise at the molecular level that not all happiness is created equal and respond in ways that can help or hinder physical health.

They found that different types of happiness have surprisingly different effects on the human genome.

People who have high levels of what is known as eudaimonic well-being — the kind of happiness that comes from having a deep sense of purpose and meaning in life — showed very favourable gene-expression profiles in their immune cells.

They had low levels of inflammatory gene expression and strong expression of antiviral and antibody genes.

However, people who had relatively high levels of hedonic well-being — the type of happiness that comes from consummatory self-gratification — actually showed just the opposite.

They had an adverse expression profile involving high inflammation and low antiviral and antibody gene expression.

Steven Cole, a University of California, Los Angeles professor of medicine, and his colleagues, including first author Barbara L. Fredrickson at the University of North Carolina, have been examining how the human genome responds to stress, misery, fear and all kinds of negative psychology.

In this study, though, the researchers asked how the human genome might respond to positive psychology.

The researchers examined the biological implications of both hedonic and eudaimonic well-being through the lens of the human genome, a system of some 21,000 genes that has evolved fundamentally to help humans survive and be well.

Previous studies had found that circulating immune cells show a systematic shift in baseline gene-expression profiles during extended periods of stress, threat or uncertainty.

Known as conserved transcriptional response to adversity, or CTRA, this shift is characterised by an increased expression of genes involved in inflammation and a decreased expression of genes involved in antiviral responses.

In the present study, the researchers drew blood samples from 80 healthy adults who were assessed for hedonic and eudaimonic well-being.

The team used the CTRA gene-expression profile to map the potentially distinct biological effects of hedonic and eudaimonic well-being.

“What this study tells us is that doing good and feeling good have very different effects on the human genome, even though they generate similar levels of positive emotion,” Dr. Cole said.

“Apparently, the human genome is much more sensitive to different ways of achieving happiness than are conscious minds,” he said.

The study was published in the journal Proceedings of the National Academy of Sciences.

More In: Health | Sci-Tech | Science