Estimating the effects of stress during operational conditions

The physiological stress index (PSI) was developed to provide a rational means for estimating the physiological and behavioral impact of exposure to physical stressors, in this case extreme temperatures and fatigue related to insufficient sleep. Stress can be life threatening and certainly threatens mission effectiveness. It is often derived from combinations of sources such as overheating and lack of sleep, particularly on individuals involved in physically demanding activities such as shipboard firefighting. The PSI was used as a performance modifying adjunct to existing discrete event simulation models designed to estimate shipboard manning requirements given various operational scenarios. Additionally, the PSI was used to estimate the most effective work rest cycles and recovery time required before selected crewmembers could be returned to duties involving significant levels of physical exertion.