Researchers assessed a group of 334 people aged 18 to 54 for their tendency to experience positive emotions like happiness, pleasure and relaxation along with negative emotions like anxiety, hostility and depression. Participants were then injected with nasal drops containing the common cold.
People who expressed more positive emotions were less likely to develop the common cold, and the relationship was so strong that it held across age, gender, education, race, body mass and even season.
Since then, psychologists have continued to probe the link between feeling good and being well in a new field of research called ‘positive psychology’. Importantly, this new discipline extends beyond disease models of health such as whether we have a cold and seeks to define what it means to be healthy in positive terms.