Locus of control and sleep in evolutionary perspective.

We examined the relationship between locus of control and sleep among firefighters using predictions driven by life history theory. Firefighters (n=115, males, aged 22-54) completed the Nowicki and Duke Locus of Control (LOC) questionnaire. Average minutes slept and sleep debt (number of nights on shift) were provided via selfreport. Statistical output supported the underlying theoretical relationship between LOC and life history strategy. Further results indicate a quadratic effect on LOC such that sleeping very little or sleeping a lot was associated with more external LOC scores when controlling for station-specific emergency response call volume and participant current health status. Finally, as sleep loss accumulates due to increasing nights on shift, LOC externality significantly increases. This data supports the notion that sleep acquisition may pose a mediating role in personality psychology in ways predicted by life history and evolutionary ecological theories.