• Connections between your nervous system and immune system allow for crosstalk between them. The science that studies this is psychoneuroimmunology
• Pessimism promotes ill health and can shave years off your life; the tendency to always expect the worst has been linked to a 25 percent higher risk of dying before the age of 65
• Sociable, outgoing people tend to have stronger immune function, and happiness, optimism, life satisfaction, and other positive psychological attributes are associated with a lower risk of heart disease

Stress

“One chemical of note involved in the HPA axis’ work is corticotropin-releasing hormone (CRH). The hypothalamus releases CRH in response to stress, illness, exercise, cortisol in the blood and sleep/wake cycles. It peaks soon after waking and slowly declines throughout the rest of the day. In a stressed individual, however, cortisol levels are elevated for prolonged periods of time.

During stress, the body believes it is in…