In the 1920-1940 period, life expectancy rose 6.2 yrs from 1929 to 1932. It declined during good economies such as 1936-37.
The speculated reasons are: people work faster and harder during economic expansions (overtime, etc.), suffer more injuries, and have less time to exercise, socialize, and they drink more and face more stress. But during downturns people have more time to sleep, to socialize, and less money to spend on drinking and smoking.
Of course, these are national averages. Being unemployed can be pretty stressful too.