Hit the sheets
“The functioning of your immune system is intimately tied to the amount and quality of sleep,” says W. Chris Winter, M.D., author of The Sleep Solution. The less sleep you get, the more depressed your immune system becomes. Aim for at least seven hours. And note that getting busy under the covers also helps: People who were intimate once or twice a week in one study had a 30 percent increase in the antigen that protects against colds and flu.