Effects of chemical protective clothing, exercise, and diphenhydramine on cognitive performance during sleep deprivation

The cognitive performance effects of some stressors experienced in military training and combat were determined in a field experiment. The effects of wearing chemical protective clothing (CPC) at Mission-Oriented Protective Posture Level IV, walking 18 to 24 miles (29-39 km) while carrying a heavy backpack, and taking 50-mg oral doses every 6 hr of diphenhydramine (an antihistamine) were investigated on 72 Marines during a 36-hr sleep deprivation double-blind, placebo-controlled experiment. We administered tests that measured reaction time, spatial ability, memory, and logical reasoning. The results suggest that wearing CPC for an Il-hr period or prolonged engagement in moderate exercise produces general cognitive impairment in sleep-deprived participants. However, after repeated dosing, taking diphenhydramine has little cognitive effect. These results suggest that, if a job is near the limit of a person's cognitive abilities, performance may suffer if the person is sleep deprived and required to wear CPC or engage in prolonged, moderate exercise.