Why would social networks be linked to affect and health practices?

OBJECTIVE: To examine the relation among social integration (SI), affect, and smoking and alcohol consumption. DESIGN: The authors administered social network and psychological questionnaires to 193 adults and then interviewed them on 14 consecutive evenings about their daily social interactions, affect, and smoking and alcohol consumption. MAIN OUTCOME MEASURES: The main outcome measures were positive and negative affect, smoking, and alcohol consumption. RESULTS: Between-subjects analyses found that those with more diverse social networks (high in SI) interacted with more people and smoked and drank less. SI was not, however, associated with affect. In contrast, within-subject analyses found that the more people participants interacted with during a day, the greater their positive affect, drinking, and smoking on that day. However, this occurred primarily for persons low in SI. High-SI persons reported high positive affect irrespective of the number of people with whom they interacted, and their smoking and drinking behaviors were less influenced by number of interactants. CONCLUSION: SI may alter health because it affects responsiveness to the social influences of others.