Under the extreme demands of combat, units historically have conducted sustained operations for a maximum of 120 hours. The result was a total deterioration of combat effectiveness. Operations in MOPP4 cause faster degradation of combat effectiveness. Though essential for endurance, sheer determination cannot offset the cumulative effects of sustained sleep loss. A unit that is subjected to extensive sustained operations requires a long period of rest and recuperation to regain combat effectiveness.
Continuous operations cause a slower, but no less serious, degradation of combat effectiveness.
Whether a task is degraded by loss of sleep depends on many interacting and sometimes counteracting factors. Complicated tasks are more stimulating to the brain and require more training to master. A simple task requires less training to do but can be boring. A soldier needs a high level of arousal to perform a task well after sleep loss. The FDC computer operators perform the most complex tasks and are usually the first to show the effects of sleep loss.