Happy people

Sunshine improves happiness significantly. Instrumenting happiness with sunshine, happier people are found to save more, spend less, and have a lower marginal propensity to consume. Happier people take more time for making decisions and have more control over expenditures; they expect a longer life and (accordingly) seem more concerned about the future than the present; they also expect less inflation in the future.

That is from a paper by Cahit Guven published in the Journal of Economic Psychology (January 2012). A draft is here (November 2007).