How Does Mood Affect Immunity?
We are slowly beginning to unravel the complex interactions between mental and physical health. Researchers have found a wealth of evidence that positive emotions can enhance the immune system, while negative emotions can suppress it. For example, individuals can take up to a year to recover a healthy immune system following the death of their spouse, and long-term caregivers have suppressed immune systems compared with persons in the general population.
Studies on survivors of sexual abuse and those with post-traumatic stress disorder suggest they have elevated levels of stress hormones, as do students at exam time. In these groups of people and others experiencing loneliness, anger, trauma and relationship problems, infections last longer and wounds take longer to heal. However, having fun with friends and family seems to have the opposite effect on our immune systems. Social contact and laughter have a measurable effect for several hours. Relaxation through massage or listening to music also reduces stress hormones.
The reasons for this link remain unclear, but the brain appears to have a direct effect on stress hormones such as adrenaline and cortisol, which have wide-ranging effects on the nervous and immune systems. In the short term, they benefit us with heightened awareness and increased energy, but when prolonged, the effects are less helpful. They lead to a profound change in the immune system, making us more likely to pick up a bug.
Stress also can overactivate the immune system, resulting in an increased risk of autoimmune diseases such as arthritis and multiple sclerosis. Skin conditions such as psoriasis, eczema, hives and acne also may worsen, and stress can trigger asthma attacks.
The mechanisms behind this are complex and still only partially understood, but what we do know is that our reactions to life events can have far-reaching effects on our health. This can work to our advantage — feelings of relaxation reduce cortisol, together with other beneficial bodily responses. In turn, these changes feed into the immune system, making it function well. This happens spontaneously in our daily lives, but we also can encourage it by choosing to look after ourselves.
Insights from the ‘placebo effect’
A mind-body link also is found in experiments where people with infections are given placebo (inactive) treatments, which they think are the real thing. Even though the treatment has no medicinal effect, these volunteers report milder symptoms than those given no treatment.
The link also can work the other way once we have developed an infection. Volunteers who are given a symptomless infection feel more anxious and depressed for the next few hours than healthy volunteers. The infection also has a detrimental effect on their memory, lasting several hours.